[{"Name":"Introduction","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Low level languages","Duration":"7m 53s","ChapterTopicVideoID":25524,"CourseChapterTopicPlaylistID":237667,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.350","Text":"Welcome to this first video on fundamental programming concepts,"},{"Start":"00:04.350 ","End":"00:06.945","Text":"where we will introduce some foundational knowledge"},{"Start":"00:06.945 ","End":"00:09.435","Text":"that sets us up for the rest of the course."},{"Start":"00:09.435 ","End":"00:11.040","Text":"By the end of this section,"},{"Start":"00:11.040 ","End":"00:15.509","Text":"you\u0027ll be able to describe the relationship between the CPU and machine language,"},{"Start":"00:15.509 ","End":"00:19.950","Text":"explain the need for and advantages of high-level languages,"},{"Start":"00:19.950 ","End":"00:24.945","Text":"compare methods of translation of high-level language to machine language,"},{"Start":"00:24.945 ","End":"00:29.810","Text":"and categorize languages according to programming paradigms."},{"Start":"00:29.810 ","End":"00:32.600","Text":"Let\u0027s get stuck in. The heart of"},{"Start":"00:32.600 ","End":"00:36.290","Text":"a computer system is commonly referred to as a processor."},{"Start":"00:36.290 ","End":"00:40.385","Text":"When I say heart, I don\u0027t mean it pumps blood around the inside of your computer."},{"Start":"00:40.385 ","End":"00:43.354","Text":"I mean, without it there would be no computer."},{"Start":"00:43.354 ","End":"00:46.910","Text":"It\u0027s the fundamental component within the system."},{"Start":"00:46.910 ","End":"00:50.450","Text":"Maybe a better word for it would be the brain of your computer."},{"Start":"00:50.450 ","End":"00:53.330","Text":"But computer scientists don\u0027t like that word being"},{"Start":"00:53.330 ","End":"00:57.860","Text":"used because it suggests that the computer can think as humans do."},{"Start":"00:57.860 ","End":"01:00.425","Text":"That certainly not the case."},{"Start":"01:00.425 ","End":"01:02.840","Text":"It\u0027s probably better to think of the processor,"},{"Start":"01:02.840 ","End":"01:07.490","Text":"which is more formally known as a central processing unit or CPU,"},{"Start":"01:07.490 ","End":"01:10.975","Text":"as a machine that faithfully carries out instructions."},{"Start":"01:10.975 ","End":"01:14.215","Text":"It\u0027s more like a calculator than a brain."},{"Start":"01:14.215 ","End":"01:20.650","Text":"Alongside the CPU, we need somewhere to store instructions and data."},{"Start":"01:20.650 ","End":"01:26.635","Text":"We also need a way of getting data into the CPU and out of the CPU."},{"Start":"01:26.635 ","End":"01:31.255","Text":"Put all these components together and you have a computer system."},{"Start":"01:31.255 ","End":"01:36.520","Text":"Early computer systems were made of individual electrical components such as switches,"},{"Start":"01:36.520 ","End":"01:39.730","Text":"relays, valves, and lights."},{"Start":"01:39.730 ","End":"01:44.605","Text":"These are all wired together and very basic processing operations could be carried out."},{"Start":"01:44.605 ","End":"01:49.885","Text":"Instructions and data could be input to the processor by turning on and off switches."},{"Start":"01:49.885 ","End":"01:52.820","Text":"Four switches, as we have here,"},{"Start":"01:52.820 ","End":"01:57.635","Text":"would allow us to input a binary value between 0 and 15."},{"Start":"01:57.635 ","End":"02:01.085","Text":"All the switches off would give us the number 0,"},{"Start":"02:01.085 ","End":"02:04.955","Text":"all the switches on would give us the number 15."},{"Start":"02:04.955 ","End":"02:14.225","Text":"Here, we could be inputting either a single 8-bit number or two 4-bit numbers,"},{"Start":"02:14.225 ","End":"02:16.250","Text":"one here and one here."},{"Start":"02:16.250 ","End":"02:19.445","Text":"Let\u0027s assume there are two 4-bit numbers."},{"Start":"02:19.445 ","End":"02:20.780","Text":"In this upper diagram,"},{"Start":"02:20.780 ","End":"02:23.240","Text":"two switches are on."},{"Start":"02:23.240 ","End":"02:26.570","Text":"Therefore, we have two 1s being input."},{"Start":"02:26.570 ","End":"02:32.195","Text":"Assuming the most significant bit is at the top representing a value of 8,"},{"Start":"02:32.195 ","End":"02:35.598","Text":"this would give us 4 plus 1."},{"Start":"02:35.598 ","End":"02:37.485","Text":"Given that this is 8,"},{"Start":"02:37.485 ","End":"02:39.495","Text":"4, 2, and 1,"},{"Start":"02:39.495 ","End":"02:42.780","Text":"the 8 and 2 bits are not set,"},{"Start":"02:42.780 ","End":"02:45.875","Text":"but the 4 and 1 bits are set,"},{"Start":"02:45.875 ","End":"02:50.975","Text":"giving us the decimal number 5 and that will be input into the system."},{"Start":"02:50.975 ","End":"02:52.940","Text":"In this lower diagram,"},{"Start":"02:52.940 ","End":"02:55.175","Text":"we\u0027ve again got a 4-bit number."},{"Start":"02:55.175 ","End":"02:56.450","Text":"Here is 8 here,"},{"Start":"02:56.450 ","End":"02:59.419","Text":"4 here, 2 here, and 1 here."},{"Start":"02:59.419 ","End":"03:03.270","Text":"Only the 2 and 1 are set and therefore,"},{"Start":"03:03.270 ","End":"03:04.705","Text":"this number is 3."},{"Start":"03:04.705 ","End":"03:08.555","Text":"We\u0027re inputting a value of 3 into the system."},{"Start":"03:08.555 ","End":"03:13.340","Text":"Results of operations can be shown as binary values by turning on lights."},{"Start":"03:13.340 ","End":"03:16.580","Text":"For example, adding these two 4-bit numbers could give us"},{"Start":"03:16.580 ","End":"03:19.790","Text":"a result that we could display on a set of lights,"},{"Start":"03:19.790 ","End":"03:23.649","Text":"each one representing 1-bit of the results."},{"Start":"03:23.649 ","End":"03:28.350","Text":"Here, adding these 2 numbers of 5 and 3 would obviously give us 8 and"},{"Start":"03:28.350 ","End":"03:34.205","Text":"the result is being shown on four lights with each one representing 1-bit of the result."},{"Start":"03:34.205 ","End":"03:39.110","Text":"The 8 here is the most significant bit with a 1,"},{"Start":"03:39.110 ","End":"03:44.045","Text":"meaning that it\u0027s going to be lit and all of the other bits are 0,"},{"Start":"03:44.045 ","End":"03:48.710","Text":"so none of the other lamps or lights will be on."},{"Start":"03:48.710 ","End":"03:52.370","Text":"Every CPU can carry out operations such as add"},{"Start":"03:52.370 ","End":"03:55.780","Text":"or subtract and we call these instructions."},{"Start":"03:55.780 ","End":"03:59.270","Text":"We know already how numeric data is encoded in binary,"},{"Start":"03:59.270 ","End":"04:01.175","Text":"but what about instructions?"},{"Start":"04:01.175 ","End":"04:04.190","Text":"Well, every CPU has a finite set of"},{"Start":"04:04.190 ","End":"04:08.480","Text":"instructions that it can carry out called an instruction set."},{"Start":"04:08.480 ","End":"04:13.625","Text":"Each instruction within the instruction set has its own unique binary value."},{"Start":"04:13.625 ","End":"04:16.610","Text":"For example, on one particular CPU,"},{"Start":"04:16.610 ","End":"04:27.085","Text":"11000110 is a unique binary value that represents an instruction to perform addition."},{"Start":"04:27.085 ","End":"04:32.450","Text":"Other unique binary values will be associated with other instructions."},{"Start":"04:32.450 ","End":"04:36.230","Text":"As well as the binary values that represent a specific instruction,"},{"Start":"04:36.230 ","End":"04:38.090","Text":"it\u0027s also necessary to supply"},{"Start":"04:38.090 ","End":"04:41.450","Text":"binary values that will represent the data that we\u0027re working with."},{"Start":"04:41.450 ","End":"04:45.020","Text":"The following binary values constitute a short program"},{"Start":"04:45.020 ","End":"04:48.665","Text":"that adds together the numbers 3 and 5."},{"Start":"04:48.665 ","End":"04:51.440","Text":"You may have noticed from the second line,"},{"Start":"04:51.440 ","End":"04:58.670","Text":"this bit pattern we saw earlier representing the instruction to add."},{"Start":"04:58.670 ","End":"05:02.675","Text":"The second bit pattern is the value,"},{"Start":"05:02.675 ","End":"05:04.850","Text":"in this case, 5."},{"Start":"05:04.850 ","End":"05:11.270","Text":"On this first line is a different instruction and the value 3."},{"Start":"05:11.270 ","End":"05:13.190","Text":"In the early days of computing,"},{"Start":"05:13.190 ","End":"05:16.820","Text":"this is how programs would have been written and entered into a processor."},{"Start":"05:16.820 ","End":"05:21.065","Text":"It\u0027s called machine language or machine code."},{"Start":"05:21.065 ","End":"05:22.880","Text":"This, obviously, has many problems."},{"Start":"05:22.880 ","End":"05:26.090","Text":"It\u0027s easy to make a mistake in a single bit being entered,"},{"Start":"05:26.090 ","End":"05:30.320","Text":"and the program would therefore be corrupted and would likely be invalid."},{"Start":"05:30.320 ","End":"05:34.130","Text":"It\u0027s also very slow to develop programs this way as many instructions and"},{"Start":"05:34.130 ","End":"05:39.455","Text":"binary data values have to be entered to achieve relatively simple results."},{"Start":"05:39.455 ","End":"05:42.290","Text":"Something called assembly language was developed"},{"Start":"05:42.290 ","End":"05:45.635","Text":"to allow slightly more meaningful program code to be entered."},{"Start":"05:45.635 ","End":"05:48.590","Text":"For example, the previous program will be much more easily"},{"Start":"05:48.590 ","End":"05:53.000","Text":"understood by using the following assembly language code."},{"Start":"05:53.000 ","End":"05:58.220","Text":"Here, we can see the numbers 3 and 5 in decimal,"},{"Start":"05:58.220 ","End":"06:01.280","Text":"which is much easier for us humans to make sense of."},{"Start":"06:01.280 ","End":"06:04.310","Text":"We can also guess the meanings of the instructions"},{"Start":"06:04.310 ","End":"06:07.310","Text":"being used using the short abbreviations,"},{"Start":"06:07.310 ","End":"06:09.185","Text":"which we call mnemonics."},{"Start":"06:09.185 ","End":"06:12.755","Text":"For a programmer using these instructions regularly,"},{"Start":"06:12.755 ","End":"06:19.850","Text":"that\u0027ll be much easier to remember than the long binary bit patterns for 00110 and so on."},{"Start":"06:19.850 ","End":"06:25.520","Text":"These assembly language instructions cannot be directly carried out by the CPU."},{"Start":"06:25.520 ","End":"06:27.980","Text":"They need to be translated into"},{"Start":"06:27.980 ","End":"06:33.550","Text":"machine language and that\u0027s done by a program called an assembler."},{"Start":"06:33.550 ","End":"06:39.260","Text":"A major issue with machine code is that it\u0027s specific to one particular type of CPU."},{"Start":"06:39.260 ","End":"06:42.740","Text":"You\u0027re probably familiar with the Intel CPU such as the i3,"},{"Start":"06:42.740 ","End":"06:45.020","Text":"the i5, or the i7,"},{"Start":"06:45.020 ","End":"06:47.150","Text":"which are commonly found in PCs."},{"Start":"06:47.150 ","End":"06:50.390","Text":"These are all developed from the same processor which originally appeared"},{"Start":"06:50.390 ","End":"06:54.470","Text":"in 1978 called the Intel 8086."},{"Start":"06:54.470 ","End":"06:59.105","Text":"These processors belong to what we call the Intel x86 family."},{"Start":"06:59.105 ","End":"07:01.625","Text":"Another type of CPU developed by a company called"},{"Start":"07:01.625 ","End":"07:05.165","Text":"ARM is found in the majority of mobile phones."},{"Start":"07:05.165 ","End":"07:12.620","Text":"The machine code for an Intel x86 CPU will not work on an ARM CPU."},{"Start":"07:12.620 ","End":"07:15.290","Text":"Each has its own instruction set with"},{"Start":"07:15.290 ","End":"07:19.325","Text":"its own unique binary codes for each available instruction."},{"Start":"07:19.325 ","End":"07:23.840","Text":"The binary value for an add instruction on an x86 CPU will"},{"Start":"07:23.840 ","End":"07:28.670","Text":"be different to the binary value for an add instruction on an ARM CPU."},{"Start":"07:28.670 ","End":"07:31.189","Text":"The same applies to assembly language,"},{"Start":"07:31.189 ","End":"07:33.695","Text":"which is also CPU specific."},{"Start":"07:33.695 ","End":"07:36.650","Text":"Collectively, machine code programs and"},{"Start":"07:36.650 ","End":"07:41.255","Text":"assembly language programs are known as low-level languages."},{"Start":"07:41.255 ","End":"07:42.815","Text":"In the next video,"},{"Start":"07:42.815 ","End":"07:45.890","Text":"we\u0027ll see how these difficulties with low-level languages were"},{"Start":"07:45.890 ","End":"07:49.910","Text":"overcome with the development of high-level languages."},{"Start":"07:49.910 ","End":"07:53.880","Text":"Thanks for watching, and I\u0027ll see you in the next one."}],"ID":26341},{"Watched":false,"Name":"high level languages","Duration":"8m 17s","ChapterTopicVideoID":25525,"CourseChapterTopicPlaylistID":237667,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.540","Text":"Welcome back, everybody. In the previous video,"},{"Start":"00:03.540 ","End":"00:05.565","Text":"we learned that early programmers used"},{"Start":"00:05.565 ","End":"00:09.400","Text":"machine code or assembly language to write their programs."},{"Start":"00:09.400 ","End":"00:14.230","Text":"This had a major disadvantage in that they were written for a specific CPU."},{"Start":"00:14.230 ","End":"00:16.730","Text":"In the case of machine code in particular,"},{"Start":"00:16.730 ","End":"00:21.290","Text":"it was very easy for errors to occur when writing and entering the program."},{"Start":"00:21.290 ","End":"00:23.360","Text":"To other companies problems,"},{"Start":"00:23.360 ","End":"00:24.830","Text":"other programming languages called"},{"Start":"00:24.830 ","End":"00:29.090","Text":"high level languages were developed from the 1950s onwards."},{"Start":"00:29.090 ","End":"00:31.310","Text":"Early high-level languages were concerned with"},{"Start":"00:31.310 ","End":"00:34.655","Text":"engineering and business-related applications."},{"Start":"00:34.655 ","End":"00:38.450","Text":"The languages allowed these sorts of applications to be developed and"},{"Start":"00:38.450 ","End":"00:42.440","Text":"maintained much more easily than was possible with machine code."},{"Start":"00:42.440 ","End":"00:47.785","Text":"Over time, a large number of high-level languages have emerged."},{"Start":"00:47.785 ","End":"00:50.775","Text":"Some are used in education,"},{"Start":"00:50.775 ","End":"00:53.630","Text":"some were attempting to improve on"},{"Start":"00:53.630 ","End":"00:56.959","Text":"the perceived failings of the earlier high-level languages,"},{"Start":"00:56.959 ","End":"00:59.844","Text":"and some were developed for specialist purposes,"},{"Start":"00:59.844 ","End":"01:05.200","Text":"such as creating interactive web pages or smartphone applications."},{"Start":"01:05.200 ","End":"01:08.140","Text":"High-level languages are called high level because they are"},{"Start":"01:08.140 ","End":"01:12.115","Text":"closer to the level of a human language than machine languages are."},{"Start":"01:12.115 ","End":"01:15.520","Text":"As you can see, the high level language is a little"},{"Start":"01:15.520 ","End":"01:20.755","Text":"closer to the human language than the machine code instructions are."},{"Start":"01:20.755 ","End":"01:23.185","Text":"As with assembly language,"},{"Start":"01:23.185 ","End":"01:27.520","Text":"the CPU cannot carry out high-level language instructions directly."},{"Start":"01:27.520 ","End":"01:29.710","Text":"They must be translated first into"},{"Start":"01:29.710 ","End":"01:34.284","Text":"machine code so the CPU can carry out each individual instruction."},{"Start":"01:34.284 ","End":"01:37.840","Text":"There are 2 ways of doing this depending on the language."},{"Start":"01:37.840 ","End":"01:41.395","Text":"When compiling, the original program code,"},{"Start":"01:41.395 ","End":"01:43.225","Text":"which we call source code,"},{"Start":"01:43.225 ","End":"01:45.520","Text":"is translated once,"},{"Start":"01:45.520 ","End":"01:51.235","Text":"and a new copy of the code translated into machine code instructions is produced."},{"Start":"01:51.235 ","End":"01:55.390","Text":"Imagine writing on a piece of paper with writing in"},{"Start":"01:55.390 ","End":"02:01.585","Text":"one language being written out onto a blank piece of paper in a different language."},{"Start":"02:01.585 ","End":"02:06.400","Text":"This, in effect, is what happens when you use a program called a compiler to"},{"Start":"02:06.400 ","End":"02:11.890","Text":"translate a high-level language from its source code into machine code."},{"Start":"02:11.890 ","End":"02:15.460","Text":"An alternative to compiling is interpreting."},{"Start":"02:15.460 ","End":"02:19.870","Text":"When interpreting, the source code is translated line-by-line"},{"Start":"02:19.870 ","End":"02:24.455","Text":"into machine code instructions by a program called an interpreter."},{"Start":"02:24.455 ","End":"02:27.454","Text":"The instructions are carried out by the CPU"},{"Start":"02:27.454 ","End":"02:30.935","Text":"as the program source code is being translated."},{"Start":"02:30.935 ","End":"02:34.580","Text":"Another way of looking at it is to imagine that this video you\u0027re"},{"Start":"02:34.580 ","End":"02:38.465","Text":"watching was recorded in a language that you can\u0027t understand."},{"Start":"02:38.465 ","End":"02:44.315","Text":"You could request a video that\u0027s been completely re-recorded in your own language."},{"Start":"02:44.315 ","End":"02:46.635","Text":"That is like compilation,"},{"Start":"02:46.635 ","End":"02:49.591","Text":"because the source material was being translated,"},{"Start":"02:49.591 ","End":"02:52.790","Text":"once and for all, into another language."},{"Start":"02:52.790 ","End":"02:55.370","Text":"The downside is you\u0027d have to wait until"},{"Start":"02:55.370 ","End":"02:59.450","Text":"the whole video is re-recorded before you could watch it."},{"Start":"02:59.450 ","End":"03:02.375","Text":"In the alternative method of translating,"},{"Start":"03:02.375 ","End":"03:08.375","Text":"interpreting, you could have someone who understands both languages sit with you,"},{"Start":"03:08.375 ","End":"03:13.310","Text":"who listens to the video and translates my spoken words and the"},{"Start":"03:13.310 ","End":"03:18.290","Text":"written on-screen text into your language as it\u0027s playing."},{"Start":"03:18.290 ","End":"03:20.840","Text":"They might occasionally have to pause the video whilst it\u0027s"},{"Start":"03:20.840 ","End":"03:24.755","Text":"playing in order to have time to speak out the translation,"},{"Start":"03:24.755 ","End":"03:30.260","Text":"but it works, and you don\u0027t need to take the time to re-record the whole video."},{"Start":"03:30.260 ","End":"03:33.110","Text":"Compilers and interpreters do the same job,"},{"Start":"03:33.110 ","End":"03:38.825","Text":"translate a high-level language into instructions that can be carried out by the CPU."},{"Start":"03:38.825 ","End":"03:42.875","Text":"Both have their own advantages and disadvantages."},{"Start":"03:42.875 ","End":"03:48.005","Text":"The advantage of compilation is that the translation takes place just once,"},{"Start":"03:48.005 ","End":"03:49.400","Text":"and then after that point,"},{"Start":"03:49.400 ","End":"03:51.980","Text":"just the translated code can be run."},{"Start":"03:51.980 ","End":"03:56.255","Text":"You don\u0027t need the compiler once the code has been translated."},{"Start":"03:56.255 ","End":"04:01.385","Text":"Another advantage is that some errors can be checked before you even run the program."},{"Start":"04:01.385 ","End":"04:07.130","Text":"The downside of compilers is you need to wait for the compilation process to complete,"},{"Start":"04:07.130 ","End":"04:12.410","Text":"and you have to do that every time you change even a single character of the code."},{"Start":"04:12.410 ","End":"04:17.795","Text":"Finally, the compilation process produces code for one particular CPU."},{"Start":"04:17.795 ","End":"04:20.615","Text":"If you want to produce code for a different CPU,"},{"Start":"04:20.615 ","End":"04:24.815","Text":"or even the same CPU running on a different operating system,"},{"Start":"04:24.815 ","End":"04:29.239","Text":"you need to run the compilation process again for that other CPU."},{"Start":"04:29.239 ","End":"04:32.900","Text":"Interpreters have their own advantages and disadvantages."},{"Start":"04:32.900 ","End":"04:39.683","Text":"An advantage is that code can be developed quickly and there\u0027s no compilation necessary,"},{"Start":"04:39.683 ","End":"04:43.205","Text":"so the changes can be very quickly tested and run."},{"Start":"04:43.205 ","End":"04:48.815","Text":"You don\u0027t need to compile several different versions of the program for different CPUs,"},{"Start":"04:48.815 ","End":"04:52.610","Text":"you just need a different interpreter for each different CPU."},{"Start":"04:52.610 ","End":"04:56.120","Text":"The downside is that every time the programs run,"},{"Start":"04:56.120 ","End":"04:59.720","Text":"every line of source code will need translating again."},{"Start":"04:59.720 ","End":"05:03.725","Text":"Not only is this slower in terms of the instructions being completed,"},{"Start":"05:03.725 ","End":"05:07.685","Text":"but the interpreter needs to be available each time the programs run."},{"Start":"05:07.685 ","End":"05:10.310","Text":"Also, for interpreted languages,"},{"Start":"05:10.310 ","End":"05:13.670","Text":"the source code needs to be available for the program to be run."},{"Start":"05:13.670 ","End":"05:17.240","Text":"This could mean security or intellectual property issues."},{"Start":"05:17.240 ","End":"05:20.300","Text":"Basically, someone can more easily steal or modify"},{"Start":"05:20.300 ","End":"05:23.405","Text":"your code if they can read the source code."},{"Start":"05:23.405 ","End":"05:26.195","Text":"As high-level languages develop through time,"},{"Start":"05:26.195 ","End":"05:29.300","Text":"different types emerged with different philosophies,"},{"Start":"05:29.300 ","End":"05:33.170","Text":"computer scientists call these programming paradigms."},{"Start":"05:33.170 ","End":"05:37.280","Text":"Most languages can be categorized as imperative languages."},{"Start":"05:37.280 ","End":"05:41.180","Text":"These languages consists of a series of commands that must be"},{"Start":"05:41.180 ","End":"05:45.475","Text":"completed in a specific order and without any deviation."},{"Start":"05:45.475 ","End":"05:48.530","Text":"Given that this is exactly how a CPU works,"},{"Start":"05:48.530 ","End":"05:52.670","Text":"it\u0027s not surprising that most high-level languages use this paradigm."},{"Start":"05:52.670 ","End":"05:57.305","Text":"Logic-based programming languages are built around rules and facts."},{"Start":"05:57.305 ","End":"05:59.870","Text":"Not every single detail of a program needs"},{"Start":"05:59.870 ","End":"06:02.900","Text":"specifying as is the case for imperative languages,"},{"Start":"06:02.900 ","End":"06:08.059","Text":"and there\u0027s information that can be logically deduced from the rules and facts."},{"Start":"06:08.059 ","End":"06:12.980","Text":"Procedural languages are a type of imperative language built around"},{"Start":"06:12.980 ","End":"06:18.110","Text":"blocks of code that the program can be built from, called procedures."},{"Start":"06:18.110 ","End":"06:21.740","Text":"The particular way that sections of program code can be"},{"Start":"06:21.740 ","End":"06:25.685","Text":"skipped or repeated is also a feature of procedural languages."},{"Start":"06:25.685 ","End":"06:27.080","Text":"Some early languages,"},{"Start":"06:27.080 ","End":"06:28.760","Text":"like Fortran and BASIC,"},{"Start":"06:28.760 ","End":"06:32.240","Text":"were later developed into procedural versions."},{"Start":"06:32.240 ","End":"06:36.470","Text":"Object oriented languages are another type of imperative language"},{"Start":"06:36.470 ","End":"06:41.555","Text":"that feature a concept called a class from which objects can be built."},{"Start":"06:41.555 ","End":"06:46.445","Text":"Objects generally interact with other objects to form a program."},{"Start":"06:46.445 ","End":"06:52.010","Text":"Finally, functional programming languages are an alternative to imperative languages,"},{"Start":"06:52.010 ","End":"06:57.665","Text":"where programs are made up of functions which map a set of values onto other values."},{"Start":"06:57.665 ","End":"07:01.730","Text":"Like logic-based languages and in contrast to imperative languages,"},{"Start":"07:01.730 ","End":"07:04.940","Text":"not every detail of what needs to be done in a program"},{"Start":"07:04.940 ","End":"07:08.765","Text":"requires explicit instructions to be given in the program."},{"Start":"07:08.765 ","End":"07:11.243","Text":"Whilst these categories are all useful,"},{"Start":"07:11.243 ","End":"07:12.350","Text":"and for some languages,"},{"Start":"07:12.350 ","End":"07:15.043","Text":"the most significant factor about the language,"},{"Start":"07:15.043 ","End":"07:18.215","Text":"most languages fall into more than 1 of the categories."},{"Start":"07:18.215 ","End":"07:22.430","Text":"For example, Java belongs to the object oriented paradigm,"},{"Start":"07:22.430 ","End":"07:25.970","Text":"but could also be considered an imperative language and has"},{"Start":"07:25.970 ","End":"07:29.525","Text":"some features that are borrowed from the functional programming paradigm."},{"Start":"07:29.525 ","End":"07:32.000","Text":"You could even write Java programs in a style that\u0027s"},{"Start":"07:32.000 ","End":"07:34.415","Text":"consistent with procedural programming."},{"Start":"07:34.415 ","End":"07:37.400","Text":"We will start this course by learning the basics of"},{"Start":"07:37.400 ","End":"07:41.525","Text":"programming in a high-level language using the procedural paradigm,"},{"Start":"07:41.525 ","End":"07:44.975","Text":"and then move on to the object oriented paradigm."},{"Start":"07:44.975 ","End":"07:48.230","Text":"That completes our introduction to this part of the course."},{"Start":"07:48.230 ","End":"07:50.270","Text":"Let\u0027s summarize what we\u0027ve covered."},{"Start":"07:50.270 ","End":"07:54.875","Text":"We\u0027ve learned how to describe the relationship between the CPU and machine language,"},{"Start":"07:54.875 ","End":"07:58.735","Text":"to explain the need for and advantages of high-level languages,"},{"Start":"07:58.735 ","End":"08:02.915","Text":"to compare methods of translation of high level language to machine language,"},{"Start":"08:02.915 ","End":"08:07.145","Text":"and to categorize languages according to the programming paradigms."},{"Start":"08:07.145 ","End":"08:11.180","Text":"Be sure to test your knowledge of what we covered here by completing the exercises,"},{"Start":"08:11.180 ","End":"08:15.770","Text":"and I\u0027ll see you in the next video where we look at the idea of syntax."},{"Start":"08:15.770 ","End":"08:18.120","Text":"Thanks very much for watching."}],"ID":26342}],"Thumbnail":null,"ID":237667},{"Name":"Basic syntax and semantics of a HLL","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Natural and Formal languages","Duration":"4m 37s","ChapterTopicVideoID":25526,"CourseChapterTopicPlaylistID":237668,"HasSubtitles":true,"ThumbnailPath":"https://www.proprep.uk/Images/Videos_Thumbnails/25526.jpeg","UploadDate":"2021-05-11T08:20:52.1270000","DurationForVideoObject":"PT4M37S","Description":null,"MetaTitle":"Natural and Formal languages: Video + Workbook | Proprep","MetaDescription":"Fundamental Programming Concepts - Basic syntax and semantics of a HLL. Watch the video made by an expert in the field. Download the workbook and maximize your learning.","Canonical":"https://www.proprep.uk/general-modules/all/principles-of-programing/fundamental-programming-concepts/basic-syntax-and-semantics-of-a-hll/vid26343","VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.360","Text":"Hello, everybody and welcome to this video in which we\u0027ll learn"},{"Start":"00:03.360 ","End":"00:06.750","Text":"some concepts that underpin all high-level languages."},{"Start":"00:06.750 ","End":"00:08.130","Text":"By the end of this section,"},{"Start":"00:08.130 ","End":"00:11.150","Text":"you\u0027ll be able to explain the meaning of the term syntax,"},{"Start":"00:11.150 ","End":"00:15.065","Text":"describe the difference between syntax and semantics,"},{"Start":"00:15.065 ","End":"00:19.725","Text":"explain why a statement can be syntactically correct but invalid,"},{"Start":"00:19.725 ","End":"00:23.475","Text":"and distinguish syntax errors from other types of error."},{"Start":"00:23.475 ","End":"00:27.090","Text":"Let\u0027s start with a very basic definition of syntax."},{"Start":"00:27.090 ","End":"00:31.950","Text":"Syntax is a set of rules for a language that are followed or broken."},{"Start":"00:31.950 ","End":"00:35.180","Text":"The rules include only using words or symbols that belong to"},{"Start":"00:35.180 ","End":"00:39.800","Text":"the language and rules for structuring the words and symbols into larger sequences,"},{"Start":"00:39.800 ","End":"00:42.665","Text":"for example, sentences or paragraphs."},{"Start":"00:42.665 ","End":"00:47.360","Text":"Most human languages have a syntax that\u0027s evolved over a long period of time."},{"Start":"00:47.360 ","End":"00:51.185","Text":"Firstly through spoken language and later in written form."},{"Start":"00:51.185 ","End":"00:53.090","Text":"This mostly happens informally,"},{"Start":"00:53.090 ","End":"00:55.925","Text":"but sometimes it can happen through formal bodies."},{"Start":"00:55.925 ","End":"01:01.355","Text":"In France, a formal body called the Academie Francaise preserves the French language by"},{"Start":"01:01.355 ","End":"01:04.070","Text":"proposing alternative French words for"},{"Start":"01:04.070 ","End":"01:07.280","Text":"ones that have crept into everyday use from other languages."},{"Start":"01:07.280 ","End":"01:09.140","Text":"For example, the word Software,"},{"Start":"01:09.140 ","End":"01:10.850","Text":"which is English in origin,"},{"Start":"01:10.850 ","End":"01:14.290","Text":"was replaced with a word logy Cl."},{"Start":"01:14.290 ","End":"01:16.280","Text":"French is an exception."},{"Start":"01:16.280 ","End":"01:20.690","Text":"Most languages tend to develop very informally."},{"Start":"01:20.690 ","End":"01:24.020","Text":"We call human languages natural languages."},{"Start":"01:24.020 ","End":"01:28.985","Text":"Natural languages have the advantage that they are flexible and forgiving."},{"Start":"01:28.985 ","End":"01:34.160","Text":"You can say things 2 different ways and the meaning would be the same."},{"Start":"01:34.160 ","End":"01:38.179","Text":"Not only do these examples show the flexibility of natural languages,"},{"Start":"01:38.179 ","End":"01:40.490","Text":"as you can say the same thing in different ways,"},{"Start":"01:40.490 ","End":"01:43.640","Text":"but also show you how forgiving the language is."},{"Start":"01:43.640 ","End":"01:47.900","Text":"You don\u0027t mean that you\u0027re going to see someone in literally 60 seconds."},{"Start":"01:47.900 ","End":"01:50.150","Text":"It could be a little more or less."},{"Start":"01:50.150 ","End":"01:51.860","Text":"Everyone reading these statements"},{"Start":"01:51.860 ","End":"01:55.430","Text":"understands that a minute doesn\u0027t mean exactly a minute."},{"Start":"01:55.430 ","End":"01:58.265","Text":"It means a relatively short period of time."},{"Start":"01:58.265 ","End":"02:00.770","Text":"Natural languages are so flexible,"},{"Start":"02:00.770 ","End":"02:03.680","Text":"you could use exactly the same words"},{"Start":"02:03.680 ","End":"02:07.130","Text":"in a different order and the meaning could be different."},{"Start":"02:07.130 ","End":"02:11.915","Text":"You could even use the same words in the same order,"},{"Start":"02:11.915 ","End":"02:14.540","Text":"and they can have a completely different meaning"},{"Start":"02:14.540 ","End":"02:18.830","Text":"because of a single character of punctuation in this case."},{"Start":"02:18.830 ","End":"02:23.210","Text":"All of these examples show how ambiguous natural languages can be."},{"Start":"02:23.210 ","End":"02:26.870","Text":"With programming languages, the CPU needs clear,"},{"Start":"02:26.870 ","End":"02:31.475","Text":"unambiguous instructions that correspond to its own instruction set."},{"Start":"02:31.475 ","End":"02:34.160","Text":"When writing programs in assembly language,"},{"Start":"02:34.160 ","End":"02:41.225","Text":"there\u0027s a direct correspondence between mnemonics and machine code instructions."},{"Start":"02:41.225 ","End":"02:46.400","Text":"It\u0027s a simple task for an assembler to look up the binary machine code value for"},{"Start":"02:46.400 ","End":"02:54.375","Text":"a particular mnemonic or the binary value for data stated in decimal in binary."},{"Start":"02:54.375 ","End":"02:59.555","Text":"High-level languages are much more complex to translate than assembly language."},{"Start":"02:59.555 ","End":"03:03.560","Text":"Another category of language is called formal languages have developed in"},{"Start":"03:03.560 ","End":"03:07.910","Text":"the fields of logic, mathematics, and programming."},{"Start":"03:07.910 ","End":"03:13.865","Text":"These formal languages allow us to define language syntax in very precise terms."},{"Start":"03:13.865 ","End":"03:16.910","Text":"This allows us to then create compilers and"},{"Start":"03:16.910 ","End":"03:20.840","Text":"interpreters that follow the rules for the given language."},{"Start":"03:20.840 ","End":"03:23.690","Text":"The languages are generally made of a core set of"},{"Start":"03:23.690 ","End":"03:27.529","Text":"keywords and symbols particular to each language."},{"Start":"03:27.529 ","End":"03:32.239","Text":"In some cases, a single keyword or symbol can perform an operation."},{"Start":"03:32.239 ","End":"03:36.185","Text":"For example, divide 1 number by another."},{"Start":"03:36.185 ","End":"03:39.440","Text":"In other cases, keywords or symbols needs to be"},{"Start":"03:39.440 ","End":"03:43.805","Text":"combined with other keywords and symbols to have any meaning."},{"Start":"03:43.805 ","End":"03:50.000","Text":"For example, comparing 2 numbers and storing the highest of the 2"},{"Start":"03:50.000 ","End":"03:56.320","Text":"in memory requires a whole series of keywords and symbols structured in a particular way."},{"Start":"03:56.320 ","End":"03:59.240","Text":"Computer scientists have devised techniques that allow"},{"Start":"03:59.240 ","End":"04:03.350","Text":"high-level languages to be expressed in an unambiguous way,"},{"Start":"04:03.350 ","End":"04:08.285","Text":"which then makes possible translation into machine language."},{"Start":"04:08.285 ","End":"04:11.825","Text":"Let\u0027s now look at an improved definition of syntax."},{"Start":"04:11.825 ","End":"04:16.279","Text":"It\u0027s the set of rules that define the precise structure"},{"Start":"04:16.279 ","End":"04:21.005","Text":"of a restricted number of words and symbols in a language."},{"Start":"04:21.005 ","End":"04:25.370","Text":"We\u0027ll pause there so you can digest the idea of natural and formal languages."},{"Start":"04:25.370 ","End":"04:29.960","Text":"In the next video, we\u0027ll build on the idea of syntax and relate it to"},{"Start":"04:29.960 ","End":"04:33.110","Text":"semantics and show some practical examples of"},{"Start":"04:33.110 ","End":"04:37.860","Text":"syntax in high-level programming languages. I\u0027ll see you then."}],"ID":26343},{"Watched":false,"Name":"Semantics and types of error","Duration":"9m 11s","ChapterTopicVideoID":25527,"CourseChapterTopicPlaylistID":237668,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.950","Text":"Hello, everyone. Welcome back."},{"Start":"00:01.950 ","End":"00:06.390","Text":"In the previous video we\u0027ve finished on an improved definition of syntax,"},{"Start":"00:06.390 ","End":"00:11.730","Text":"to that let\u0027s add another definition that builds on the concept of syntax."},{"Start":"00:11.730 ","End":"00:15.075","Text":"Semantics referred to meaning,"},{"Start":"00:15.075 ","End":"00:21.300","Text":"the meaning derived from a set of syntactically valid statements and expressions."},{"Start":"00:21.300 ","End":"00:24.030","Text":"I could write a sentence in English which uses"},{"Start":"00:24.030 ","End":"00:27.180","Text":"the correct basic syntax but has no meaning."},{"Start":"00:27.180 ","End":"00:31.995","Text":"As you can see the syntax is valid only words that belong to the English language,"},{"Start":"00:31.995 ","End":"00:34.590","Text":"capital letters at the beginning of the sentence,"},{"Start":"00:34.590 ","End":"00:38.010","Text":"spaces between words and a full stop at the end of the sentence."},{"Start":"00:38.010 ","End":"00:44.375","Text":"The sentence is syntactically valid but no meaning can be derived from it."},{"Start":"00:44.375 ","End":"00:47.480","Text":"Natural languages have grammar rules which define"},{"Start":"00:47.480 ","End":"00:51.304","Text":"how the words in a language fit together to form sentences."},{"Start":"00:51.304 ","End":"00:54.020","Text":"For example, in a typical sentence in English,"},{"Start":"00:54.020 ","End":"00:55.640","Text":"you might see the following form."},{"Start":"00:55.640 ","End":"00:58.355","Text":"Subject, verb, object."},{"Start":"00:58.355 ","End":"01:00.950","Text":"The subject, that thing we\u0027re talking about,"},{"Start":"01:00.950 ","End":"01:03.275","Text":"the verb is what the subject is doing,"},{"Start":"01:03.275 ","End":"01:06.950","Text":"and the object is what the subject is doing it to."},{"Start":"01:06.950 ","End":"01:12.100","Text":"Grammar rules can be thought of as another stage after syntax rules,"},{"Start":"01:12.100 ","End":"01:17.870","Text":"however, even grammar rules can be followed and result in something that has no meaning."},{"Start":"01:17.870 ","End":"01:22.115","Text":"Natural languages must relate to some concept in the real world."},{"Start":"01:22.115 ","End":"01:24.740","Text":"If a statement follows syntax rules and follows"},{"Start":"01:24.740 ","End":"01:28.175","Text":"grammar rules but doesn\u0027t relate to concepts in the real world,"},{"Start":"01:28.175 ","End":"01:30.100","Text":"then it still has no meaning."},{"Start":"01:30.100 ","End":"01:34.325","Text":"In this example, a leaf is not capable of eating a panda,"},{"Start":"01:34.325 ","End":"01:39.785","Text":"so the statement makes no sense as no real-world concept relate to this statement."},{"Start":"01:39.785 ","End":"01:43.535","Text":"Even a sentence that has correct syntax, and correct grammar,"},{"Start":"01:43.535 ","End":"01:44.945","Text":"and has a meaning,"},{"Start":"01:44.945 ","End":"01:49.715","Text":"as an isolated sentence might not have meaning when you use out of context."},{"Start":"01:49.715 ","End":"01:51.680","Text":"Here the first sentence makes sense,"},{"Start":"01:51.680 ","End":"01:54.738","Text":"the red sentence in isolation also makes sense,"},{"Start":"01:54.738 ","End":"01:57.485","Text":"and the third sentence makes sense."},{"Start":"01:57.485 ","End":"02:00.530","Text":"But all 3 together in sequence,"},{"Start":"02:00.530 ","End":"02:04.350","Text":"the red sentence doesn\u0027t have any meaning in relation to the other 2."},{"Start":"02:04.350 ","End":"02:07.430","Text":"Humans are great at being able to deal with situations where data\u0027s"},{"Start":"02:07.430 ","End":"02:11.690","Text":"incomplete or inconsistent or even completely absent."},{"Start":"02:11.690 ","End":"02:14.390","Text":"They often use the context to guess at meaning"},{"Start":"02:14.390 ","End":"02:17.390","Text":"and just ignore anything not relevant to the context."},{"Start":"02:17.390 ","End":"02:19.130","Text":"In the paragraph here,"},{"Start":"02:19.130 ","End":"02:21.890","Text":"a human could easily ignore the red text."},{"Start":"02:21.890 ","End":"02:26.630","Text":"Machines can really struggle to cope with those same scenarios, for this reason,"},{"Start":"02:26.630 ","End":"02:30.470","Text":"formal languages don\u0027t rely on context and are, therefore,"},{"Start":"02:30.470 ","End":"02:36.545","Text":"called context-free languages or described as being the result of context-free grammar."},{"Start":"02:36.545 ","End":"02:37.955","Text":"In a formal language,"},{"Start":"02:37.955 ","End":"02:41.044","Text":"statements are either valid or invalid."},{"Start":"02:41.044 ","End":"02:46.225","Text":"When a compiler or interpreter comes across a statement which is invalid, it just stops."},{"Start":"02:46.225 ","End":"02:50.450","Text":"Contrast that with a human who would carry on when they don\u0027t understand"},{"Start":"02:50.450 ","End":"02:55.025","Text":"something and do the best job they can with whatever information is available."},{"Start":"02:55.025 ","End":"02:59.090","Text":"In formal languages, there are mechanical set of rules that must be"},{"Start":"02:59.090 ","End":"03:03.455","Text":"followed for statements or expressions in the language to be valid."},{"Start":"03:03.455 ","End":"03:08.705","Text":"A notation that can be used to create formal languages is called Backus Naur Form."},{"Start":"03:08.705 ","End":"03:11.810","Text":"Here, we can see that unsigned integers are being defined as"},{"Start":"03:11.810 ","End":"03:16.835","Text":"one or more digits that belonged to a set that\u0027s defined in the second line,"},{"Start":"03:16.835 ","End":"03:21.835","Text":"only those characters will be valid in an unsigned integer."},{"Start":"03:21.835 ","End":"03:24.975","Text":"Because a programming languages are formal language,"},{"Start":"03:24.975 ","End":"03:29.750","Text":"when a compiler or interpreter comes across an invalid expression or statement,"},{"Start":"03:29.750 ","End":"03:32.750","Text":"it will stop with a message we call a syntax error."},{"Start":"03:32.750 ","End":"03:35.885","Text":"The message may not include the word syntax but nonetheless,"},{"Start":"03:35.885 ","End":"03:40.684","Text":"is trying to tell the programmer that statement in the program is invalid."},{"Start":"03:40.684 ","End":"03:42.845","Text":"In this example,"},{"Start":"03:42.845 ","End":"03:47.975","Text":"most programming languages expect the line to be terminated with a semicolon."},{"Start":"03:47.975 ","End":"03:50.060","Text":"Here it\u0027s missing and, therefore,"},{"Start":"03:50.060 ","End":"03:54.275","Text":"the syntax error that appears is semicolon expected."},{"Start":"03:54.275 ","End":"03:57.125","Text":"In this particular error message,"},{"Start":"03:57.125 ","End":"03:59.900","Text":"we\u0027re seeing that there is an opening pair of"},{"Start":"03:59.900 ","End":"04:03.695","Text":"speech marks but no closing pair of speech marks here,"},{"Start":"04:03.695 ","End":"04:08.785","Text":"so the error message that\u0027s reported is unclosed string literal."},{"Start":"04:08.785 ","End":"04:13.850","Text":"Here, we\u0027re getting the message package system does not exist."},{"Start":"04:13.850 ","End":"04:18.710","Text":"That\u0027s because the word system over here has been spelled with a lowercase s,"},{"Start":"04:18.710 ","End":"04:21.425","Text":"many high-level languages are case sensitive."},{"Start":"04:21.425 ","End":"04:23.210","Text":"In this particular example,"},{"Start":"04:23.210 ","End":"04:28.100","Text":"the package of code that the print line command belongs to can\u0027t be"},{"Start":"04:28.100 ","End":"04:30.620","Text":"found because the compiler has been directed to"},{"Start":"04:30.620 ","End":"04:33.350","Text":"a package called system with a lowercase s,"},{"Start":"04:33.350 ","End":"04:37.085","Text":"which doesn\u0027t actually exist, hence the error."},{"Start":"04:37.085 ","End":"04:41.240","Text":"Now, this final statement here is actually syntactically correct."},{"Start":"04:41.240 ","End":"04:42.430","Text":"It has a semicolon,"},{"Start":"04:42.430 ","End":"04:46.250","Text":"has allowed operators and symbols but it just has no meaning."},{"Start":"04:46.250 ","End":"04:49.565","Text":"So that actually makes it a semantic error not a syntax error,"},{"Start":"04:49.565 ","End":"04:52.280","Text":"however programmers rarely call it that they would generally"},{"Start":"04:52.280 ","End":"04:55.545","Text":"call all of these types of error syntax errors."},{"Start":"04:55.545 ","End":"05:00.005","Text":"A better phrase might be a compile-time error because"},{"Start":"05:00.005 ","End":"05:02.240","Text":"for compiled languages they\u0027re picked up by"},{"Start":"05:02.240 ","End":"05:04.910","Text":"compiler before the programs ever able to run."},{"Start":"05:04.910 ","End":"05:08.900","Text":"Sometimes you might want the compiler or interpreter to deliberately ignore"},{"Start":"05:08.900 ","End":"05:13.055","Text":"some texts and to not even attempt to compile or interpret it."},{"Start":"05:13.055 ","End":"05:15.760","Text":"This is known as adding comments to the program."},{"Start":"05:15.760 ","End":"05:18.290","Text":"Adding comments allows you to annotate the program to"},{"Start":"05:18.290 ","End":"05:21.350","Text":"explain what a line or section of code is doing."},{"Start":"05:21.350 ","End":"05:23.840","Text":"The syntax varies according to the language but it\u0027s"},{"Start":"05:23.840 ","End":"05:27.635","Text":"usually a single symbol or 2 symbols."},{"Start":"05:27.635 ","End":"05:31.010","Text":"Here in Python, it\u0027s the hash symbol,"},{"Start":"05:31.010 ","End":"05:32.730","Text":"in C or C++,"},{"Start":"05:32.730 ","End":"05:36.020","Text":"it\u0027s 2 forward slashes and everything on"},{"Start":"05:36.020 ","End":"05:39.590","Text":"the line after the 2 forward slashes will be ignored,"},{"Start":"05:39.590 ","End":"05:41.835","Text":"in C++ and again,"},{"Start":"05:41.835 ","End":"05:44.285","Text":"Java from multi-line comment,"},{"Start":"05:44.285 ","End":"05:49.280","Text":"you can put forward slash and an asterisk character that will comment out"},{"Start":"05:49.280 ","End":"05:56.600","Text":"multiple lines until it encounters a asterisk and a forward slash which ends the comment."},{"Start":"05:56.600 ","End":"05:58.063","Text":"Just to reiterate,"},{"Start":"05:58.063 ","End":"06:01.655","Text":"anything after the comment symbol is ignored by the compiler or"},{"Start":"06:01.655 ","End":"06:05.990","Text":"interpreter so syntax rules don\u0027t apply, anything goes."},{"Start":"06:05.990 ","End":"06:08.990","Text":"There are 3 main categories of errors that you might come across"},{"Start":"06:08.990 ","End":"06:12.245","Text":"when developing programs and we\u0027ll state them here,"},{"Start":"06:12.245 ","End":"06:14.450","Text":"syntax or compile-time errors,"},{"Start":"06:14.450 ","End":"06:17.745","Text":"runtime errors, or logical errors."},{"Start":"06:17.745 ","End":"06:20.080","Text":"Syntax errors we\u0027ve already covered,"},{"Start":"06:20.080 ","End":"06:23.360","Text":"codes check to see whether it\u0027s valid or invalid when mechanically"},{"Start":"06:23.360 ","End":"06:27.005","Text":"following some rules around what is allowed and in this case,"},{"Start":"06:27.005 ","End":"06:30.050","Text":"we\u0027re missing a pair of closing speech marks,"},{"Start":"06:30.050 ","End":"06:33.320","Text":"we\u0027ve got the opening ones here but not any closing ones,"},{"Start":"06:33.320 ","End":"06:36.470","Text":"and the compiler is going to signal a syntax error when"},{"Start":"06:36.470 ","End":"06:39.800","Text":"this program is compiled or in an interpreted language,"},{"Start":"06:39.800 ","End":"06:42.515","Text":"the arrow will appear when this particular line is run."},{"Start":"06:42.515 ","End":"06:45.520","Text":"Runtime errors are more subtle type of error,"},{"Start":"06:45.520 ","End":"06:48.530","Text":"they involve some external dependency."},{"Start":"06:48.530 ","End":"06:50.810","Text":"The code is syntactically correct,"},{"Start":"06:50.810 ","End":"06:53.540","Text":"the keywords are known and the arrangement of keywords and symbols is"},{"Start":"06:53.540 ","End":"06:57.440","Text":"valid but an error occurs under certain situations."},{"Start":"06:57.440 ","End":"07:02.735","Text":"This type of error compiler would not signal an error because the code looks okay."},{"Start":"07:02.735 ","End":"07:07.100","Text":"Even an interpreter would run the line and it could work, however,"},{"Start":"07:07.100 ","End":"07:10.130","Text":"the interesting word there is that it could work,"},{"Start":"07:10.130 ","End":"07:15.965","Text":"it all depends on whether this file being opened is available or not."},{"Start":"07:15.965 ","End":"07:17.570","Text":"The file might have been deleted,"},{"Start":"07:17.570 ","End":"07:19.850","Text":"moved or renamed, and, therefore,"},{"Start":"07:19.850 ","End":"07:22.325","Text":"the system might not be able to find it."},{"Start":"07:22.325 ","End":"07:25.160","Text":"There\u0027s no way of the compiler knowing this in advance"},{"Start":"07:25.160 ","End":"07:28.130","Text":"the first time the interpret or to even check is it"},{"Start":"07:28.130 ","End":"07:31.010","Text":"when it tries to open the file and then it"},{"Start":"07:31.010 ","End":"07:34.505","Text":"fails and it will generate an error message and the program would stop."},{"Start":"07:34.505 ","End":"07:37.230","Text":"Same goes for compile program too."},{"Start":"07:37.230 ","End":"07:39.230","Text":"This gives us an indication of why"},{"Start":"07:39.230 ","End":"07:41.960","Text":"syntax errors are sometimes called compile-time errors,"},{"Start":"07:41.960 ","End":"07:45.365","Text":"they can be picked up before the programs even run."},{"Start":"07:45.365 ","End":"07:50.655","Text":"However, a runtime error can only be detected when the program is running."},{"Start":"07:50.655 ","End":"07:54.205","Text":"The final category is the logical error."},{"Start":"07:54.205 ","End":"07:56.710","Text":"In this program, we\u0027re supposed to output"},{"Start":"07:56.710 ","End":"07:59.980","Text":"a message saying which is the highest of 2 numbers,"},{"Start":"07:59.980 ","End":"08:01.570","Text":"a or b, however,"},{"Start":"08:01.570 ","End":"08:03.475","Text":"there is a logical error here."},{"Start":"08:03.475 ","End":"08:06.700","Text":"If a is exactly equal to b,"},{"Start":"08:06.700 ","End":"08:10.210","Text":"the program will output b is bigger than a."},{"Start":"08:10.210 ","End":"08:11.520","Text":"There\u0027s no syntax errors,"},{"Start":"08:11.520 ","End":"08:13.240","Text":"the syntax actually, all correct."},{"Start":"08:13.240 ","End":"08:15.115","Text":"There\u0027s no runtime error either,"},{"Start":"08:15.115 ","End":"08:18.340","Text":"as there\u0027s nothing in these lines that depends on anything external."},{"Start":"08:18.340 ","End":"08:20.560","Text":"The error is just that the program doesn\u0027t do what"},{"Start":"08:20.560 ","End":"08:22.690","Text":"we want it to do and it\u0027s the thing with computers,"},{"Start":"08:22.690 ","End":"08:24.190","Text":"they do what you tell them to do,"},{"Start":"08:24.190 ","End":"08:25.780","Text":"not what you want them to do."},{"Start":"08:25.780 ","End":"08:28.285","Text":"Beginner programmers are going to encounter"},{"Start":"08:28.285 ","End":"08:31.870","Text":"all 3 of these types of error when learning how to program."},{"Start":"08:31.870 ","End":"08:33.130","Text":"At the beginning,"},{"Start":"08:33.130 ","End":"08:35.155","Text":"syntax errors will be the most common,"},{"Start":"08:35.155 ","End":"08:37.620","Text":"then it\u0027ll be mostly logical errors,"},{"Start":"08:37.620 ","End":"08:43.025","Text":"runtime errors you only really encounter under quite specific circumstances."},{"Start":"08:43.025 ","End":"08:45.170","Text":"So you don\u0027t see them as often."},{"Start":"08:45.170 ","End":"08:49.700","Text":"So that\u0027s it for this video where we looked at the meaning of the term syntax."},{"Start":"08:49.700 ","End":"08:52.100","Text":"In this section, we learned how to explain the meaning of"},{"Start":"08:52.100 ","End":"08:56.195","Text":"the term syntax to describe the difference between syntax and semantics,"},{"Start":"08:56.195 ","End":"09:00.195","Text":"to explain why a statement can be syntactically correct but invalid and"},{"Start":"09:00.195 ","End":"09:04.340","Text":"to distinguish syntax errors from other types of error."},{"Start":"09:04.340 ","End":"09:07.940","Text":"Thanks very much and I\u0027ll see you in the next one where start to write"},{"Start":"09:07.940 ","End":"09:12.450","Text":"simple statements in high-level languages. Thanks, again."}],"ID":26344},{"Watched":false,"Name":"Exercise 1","Duration":"3m 38s","ChapterTopicVideoID":26926,"CourseChapterTopicPlaylistID":237668,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.050 ","End":"00:04.020","Text":"Hi everyone, welcome to this first exercise in which we"},{"Start":"00:04.020 ","End":"00:08.750","Text":"discuss the differences between natural and formal languages."},{"Start":"00:08.750 ","End":"00:10.470","Text":"The first part, Part A,"},{"Start":"00:10.470 ","End":"00:15.285","Text":"asks us to describe 2 advantages of natural languages over formal languages."},{"Start":"00:15.285 ","End":"00:18.570","Text":"Natural languages being ones spoken by humans."},{"Start":"00:18.570 ","End":"00:20.970","Text":"For example, English, Spanish, etc."},{"Start":"00:20.970 ","End":"00:23.760","Text":"Formal languages being things like maths,"},{"Start":"00:23.760 ","End":"00:27.209","Text":"logic, and programming languages."},{"Start":"00:27.209 ","End":"00:31.440","Text":"The first advantage we might want to talk about when we\u0027re talking about"},{"Start":"00:31.440 ","End":"00:35.970","Text":"natural languages would be the flexibility inherent in natural languages."},{"Start":"00:35.970 ","End":"00:38.570","Text":"Because there\u0027s many ways of saying things in"},{"Start":"00:38.570 ","End":"00:41.930","Text":"most languages to achieve some particular outcome."},{"Start":"00:41.930 ","End":"00:44.885","Text":"That\u0027s not the case for formal languages."},{"Start":"00:44.885 ","End":"00:47.765","Text":"They tend to provide a very limited set of"},{"Start":"00:47.765 ","End":"00:51.605","Text":"permitted operations and keywords to achieve whatever the outcome is."},{"Start":"00:51.605 ","End":"00:55.714","Text":"We\u0027d have a symbol that represents addition."},{"Start":"00:55.714 ","End":"00:59.930","Text":"There is only 1 symbol that has that function."},{"Start":"00:59.930 ","End":"01:02.945","Text":"Similarly for multiplication, division, and so on."},{"Start":"01:02.945 ","End":"01:07.295","Text":"But we would have a lot of words in natural languages perhaps,"},{"Start":"01:07.295 ","End":"01:11.225","Text":"to describe 1 particular thing and they all mean the same thing."},{"Start":"01:11.225 ","End":"01:13.700","Text":"That\u0027s not the case generally with formal languages are"},{"Start":"01:13.700 ","End":"01:17.330","Text":"much more restricted set of operations and keywords."},{"Start":"01:17.330 ","End":"01:21.349","Text":"The other difference would be around precision."},{"Start":"01:21.349 ","End":"01:25.370","Text":"You can get away with in natural languages, lack of precision."},{"Start":"01:25.370 ","End":"01:31.055","Text":"That\u0027s not something you can do in formal languages because you don\u0027t want to."},{"Start":"01:31.055 ","End":"01:36.425","Text":"Formal languages rely on context and conventions and any other information."},{"Start":"01:36.425 ","End":"01:39.665","Text":"When you\u0027re trying to understand the meaning of a particular statement,"},{"Start":"01:39.665 ","End":"01:41.570","Text":"a compiler has to understand the meaning and"},{"Start":"01:41.570 ","End":"01:45.245","Text":"ultimately the CPU has to carry out those instructions."},{"Start":"01:45.245 ","End":"01:47.940","Text":"Formal languages are very literal."},{"Start":"01:47.940 ","End":"01:50.750","Text":"If you were talking about a time, for example,"},{"Start":"01:50.750 ","End":"01:56.405","Text":"it would be an exact time or at a time within a certain range with a certain tolerance."},{"Start":"01:56.405 ","End":"01:58.280","Text":"If we say 30 seconds,"},{"Start":"01:58.280 ","End":"02:00.170","Text":"it will be exactly 30 seconds."},{"Start":"02:00.170 ","End":"02:04.100","Text":"If we say 30 seconds with a tolerance of 5 seconds,"},{"Start":"02:04.100 ","End":"02:07.190","Text":"then it would be 25-35 seconds."},{"Start":"02:07.190 ","End":"02:12.529","Text":"In that way, natural languages are a lot more flexible than formal languages."},{"Start":"02:12.529 ","End":"02:15.650","Text":"In Part B, we then are asked what feature of"},{"Start":"02:15.650 ","End":"02:19.325","Text":"natural languages makes formal languages necessary for programming."},{"Start":"02:19.325 ","End":"02:23.025","Text":"That really leads back to what we\u0027ve just said for Part A."},{"Start":"02:23.025 ","End":"02:25.640","Text":"It\u0027s the flexibility of natural language."},{"Start":"02:25.640 ","End":"02:28.255","Text":"That\u0027s an advantage, but also a disadvantage,"},{"Start":"02:28.255 ","End":"02:31.520","Text":"and that we can have some ambiguity."},{"Start":"02:31.520 ","End":"02:34.610","Text":"Statements in a natural language are"},{"Start":"02:34.610 ","End":"02:38.225","Text":"difficult for a compiler or an interpreter to translate"},{"Start":"02:38.225 ","End":"02:42.710","Text":"into the exact machine code instructions that a CPU"},{"Start":"02:42.710 ","End":"02:47.630","Text":"can understand because it can only understand machine code instructions ultimately."},{"Start":"02:47.630 ","End":"02:50.780","Text":"This formal language lets us have"},{"Start":"02:50.780 ","End":"02:55.130","Text":"a very restricted set of symbols and keywords and structures"},{"Start":"02:55.130 ","End":"02:59.100","Text":"that allow for unambiguous interpretation and we can"},{"Start":"02:59.100 ","End":"03:02.930","Text":"then directly translate those symbols,"},{"Start":"03:02.930 ","End":"03:06.080","Text":"keywords, and structures into machine code instructions in"},{"Start":"03:06.080 ","End":"03:09.935","Text":"a way that would be difficult to do with natural languages."},{"Start":"03:09.935 ","End":"03:14.840","Text":"That\u0027s really what we\u0027re looking for in those 2 parts of this exercise,"},{"Start":"03:14.840 ","End":"03:18.080","Text":"really this understanding that natural languages are great in"},{"Start":"03:18.080 ","End":"03:21.995","Text":"the sense that there\u0027s a lot of flexibility and informality with them."},{"Start":"03:21.995 ","End":"03:24.920","Text":"Formal languages by definition,"},{"Start":"03:24.920 ","End":"03:29.135","Text":"have a much more restricted set of operations."},{"Start":"03:29.135 ","End":"03:35.975","Text":"Therefore, they can be very easily translated into specific machine code instructions."},{"Start":"03:35.975 ","End":"03:39.030","Text":"That\u0027s it for this one, I\u0027ll see you in the next one."}],"ID":28018},{"Watched":false,"Name":"Exercise 2","Duration":"5m 12s","ChapterTopicVideoID":26927,"CourseChapterTopicPlaylistID":237668,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.850","Text":"Hello, again. In this exercise,"},{"Start":"00:02.850 ","End":"00:07.020","Text":"we\u0027ve been asked to agree with the statement with a definition here,"},{"Start":"00:07.020 ","End":"00:08.910","Text":"which is about syntax."},{"Start":"00:08.910 ","End":"00:12.030","Text":"It says syntax can be defined as the set of rules that define"},{"Start":"00:12.030 ","End":"00:17.070","Text":"the precise structure of a restricted number of words and symbols in a language."},{"Start":"00:17.070 ","End":"00:19.600","Text":"In part a, we were invited to say to"},{"Start":"00:19.600 ","End":"00:24.555","Text":"what degree that definition applies for a natural language."},{"Start":"00:24.555 ","End":"00:29.070","Text":"The implication there is for formal languages and natural languages,"},{"Start":"00:29.070 ","End":"00:33.720","Text":"this definition applies, but it applies less for 1 of those."},{"Start":"00:33.720 ","End":"00:38.330","Text":"I don\u0027t think it\u0027d be a surprise for you to workout that applies to both,"},{"Start":"00:38.330 ","End":"00:41.750","Text":"but to a lesser degree for natural languages."},{"Start":"00:41.750 ","End":"00:43.940","Text":"Because as we said previously,"},{"Start":"00:43.940 ","End":"00:48.980","Text":"they allow more flexibility due to less strict rules that are"},{"Start":"00:48.980 ","End":"00:51.455","Text":"applied when we are trying to"},{"Start":"00:51.455 ","End":"00:55.370","Text":"understand the meaning of some statement in the natural language."},{"Start":"00:55.370 ","End":"00:57.680","Text":"A lot of that is also to do with"},{"Start":"00:57.680 ","End":"01:04.025","Text":"the very large vocabulary that you\u0027d have in a typical human language."},{"Start":"01:04.025 ","End":"01:06.680","Text":"If you contrast that with a formal language,"},{"Start":"01:06.680 ","End":"01:08.240","Text":"a programming language like Java,"},{"Start":"01:08.240 ","End":"01:11.270","Text":"there\u0027s only about 60 keywords in Java."},{"Start":"01:11.270 ","End":"01:14.480","Text":"Whereas the average adult who is"},{"Start":"01:14.480 ","End":"01:18.875","Text":"an English speaker would know tens of thousands of words in English."},{"Start":"01:18.875 ","End":"01:22.580","Text":"There\u0027s a huge, huge difference in the size of"},{"Start":"01:22.580 ","End":"01:26.705","Text":"the vocabulary of natural and formal languages."},{"Start":"01:26.705 ","End":"01:32.045","Text":"That\u0027s the first part of the answer to part a."},{"Start":"01:32.045 ","End":"01:35.930","Text":"In part b, we\u0027re asked to describe how it\u0027s possible"},{"Start":"01:35.930 ","End":"01:39.890","Text":"for an expression in a language to use the correct syntax,"},{"Start":"01:39.890 ","End":"01:42.595","Text":"but to still be invalid."},{"Start":"01:42.595 ","End":"01:46.205","Text":"This is really about the understanding of the difference between"},{"Start":"01:46.205 ","End":"01:50.125","Text":"syntax being correct and semantics."},{"Start":"01:50.125 ","End":"01:54.020","Text":"This idea that semantics is all about the meaning of something."},{"Start":"01:54.020 ","End":"01:57.200","Text":"Somebody could be syntactically correct but have"},{"Start":"01:57.200 ","End":"02:01.625","Text":"no meaning and that would make it invalid in the language being used."},{"Start":"02:01.625 ","End":"02:04.490","Text":"We look at that for a natural language,"},{"Start":"02:04.490 ","End":"02:08.020","Text":"it might be down to grammar rules that have been broken."},{"Start":"02:08.020 ","End":"02:11.945","Text":"That would potentially make a statement confusing"},{"Start":"02:11.945 ","End":"02:15.680","Text":"or if it\u0027s serious enough grammar rule that has been broken,"},{"Start":"02:15.680 ","End":"02:18.295","Text":"it just could be completely meaningless what\u0027s being said."},{"Start":"02:18.295 ","End":"02:24.140","Text":"There could be an issue with a paragraph where there are multiple sentences"},{"Start":"02:24.140 ","End":"02:26.780","Text":"in a natural language where 1 of them makes"},{"Start":"02:26.780 ","End":"02:30.125","Text":"no sense in the context of the other sentences."},{"Start":"02:30.125 ","End":"02:32.405","Text":"Again, there\u0027s confusion there."},{"Start":"02:32.405 ","End":"02:36.185","Text":"It doesn\u0027t mean the whole paragraph is rendered meaningless,"},{"Start":"02:36.185 ","End":"02:38.000","Text":"but some of it is meaningless."},{"Start":"02:38.000 ","End":"02:41.600","Text":"Generally, we would tend to ignore them meaningless bits and"},{"Start":"02:41.600 ","End":"02:45.335","Text":"put the sentences into some overall context."},{"Start":"02:45.335 ","End":"02:51.710","Text":"Finally, the statement that\u0027s made could also make no sense essentially."},{"Start":"02:51.710 ","End":"02:53.825","Text":"Bears no relationship to"},{"Start":"02:53.825 ","End":"02:59.265","Text":"a real-world concept and that would also make it invalid in the example we gave."},{"Start":"02:59.265 ","End":"03:03.440","Text":"When we looked at this in the video was this idea of"},{"Start":"03:03.440 ","End":"03:08.795","Text":"an animal eating something vegetable or fruit."},{"Start":"03:08.795 ","End":"03:13.730","Text":"That makes sense but the fruit or vegetable could not eat the animal,"},{"Start":"03:13.730 ","End":"03:16.850","Text":"even though in the grammar it might be correct."},{"Start":"03:16.850 ","End":"03:19.520","Text":"It just doesn\u0027t make sense in the real world."},{"Start":"03:19.520 ","End":"03:22.385","Text":"That would also render it invalid."},{"Start":"03:22.385 ","End":"03:27.480","Text":"That\u0027s part b dealt with and the final part c,"},{"Start":"03:27.480 ","End":"03:32.030","Text":"what advantage do humans using natural languages have over machines using"},{"Start":"03:32.030 ","End":"03:38.780","Text":"formal languages in terms of longer sequences of expressions and statements?"},{"Start":"03:38.780 ","End":"03:42.620","Text":"This advantage that human has when they\u0027re using natural languages."},{"Start":"03:42.620 ","End":"03:48.560","Text":"They can just simply ignore things that are invalid because they can guess things using"},{"Start":"03:48.560 ","End":"03:51.590","Text":"the context or they can actually make use of"},{"Start":"03:51.590 ","End":"03:55.760","Text":"inaccurate or incomplete data and fill in the gaps."},{"Start":"03:55.760 ","End":"04:00.365","Text":"Or just recognize that something might not be fully accurate,"},{"Start":"04:00.365 ","End":"04:04.040","Text":"but it would be good enough in terms of information provided"},{"Start":"04:04.040 ","End":"04:08.150","Text":"to deliver on what the outcome was and a map is a great example of that."},{"Start":"04:08.150 ","End":"04:11.315","Text":"Someone can give you directions or someone could draw you a map."},{"Start":"04:11.315 ","End":"04:13.070","Text":"It\u0027s not fully accurate."},{"Start":"04:13.070 ","End":"04:15.485","Text":"It might even have some bits missing,"},{"Start":"04:15.485 ","End":"04:20.675","Text":"but you can still work out where you need to go from this map that\u0027s been drawn,"},{"Start":"04:20.675 ","End":"04:24.684","Text":"even if it\u0027s not completely accurate or complete."},{"Start":"04:24.684 ","End":"04:31.660","Text":"Contrast there is a machine just cannot do this when it\u0027s using a formal language."},{"Start":"04:31.660 ","End":"04:34.295","Text":"If it encounters an invalid statement,"},{"Start":"04:34.295 ","End":"04:38.385","Text":"it has to stop and report an error."},{"Start":"04:38.385 ","End":"04:40.620","Text":"That was it for this exercise."},{"Start":"04:40.620 ","End":"04:45.065","Text":"The 3 parts really are all about the differences between"},{"Start":"04:45.065 ","End":"04:48.530","Text":"natural and formal languages and the consequences of"},{"Start":"04:48.530 ","End":"04:52.700","Text":"those differences for us when it comes to programming,"},{"Start":"04:52.700 ","End":"04:55.295","Text":"because we are going to encounter errors,"},{"Start":"04:55.295 ","End":"04:59.630","Text":"and they will stop the CPU from being able to execute"},{"Start":"04:59.630 ","End":"05:02.690","Text":"any instructions or it might even stop"},{"Start":"05:02.690 ","End":"05:06.950","Text":"the compiler before we even get to the CPU running any instructions."},{"Start":"05:06.950 ","End":"05:10.385","Text":"It will simply stop and we can\u0027t go any further."},{"Start":"05:10.385 ","End":"05:13.580","Text":"That\u0027s it for this 1. I\u0027ll see you soon."}],"ID":28019},{"Watched":false,"Name":"Exercise 3","Duration":"4m 1s","ChapterTopicVideoID":26928,"CourseChapterTopicPlaylistID":237668,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.610","Text":"Hello, again. In this question,"},{"Start":"00:02.610 ","End":"00:05.175","Text":"we\u0027ve been asked to say whether"},{"Start":"00:05.175 ","End":"00:10.965","Text":"a compile time error might be a better way of describing a syntax error,"},{"Start":"00:10.965 ","End":"00:16.215","Text":"and we\u0027ve been told that compilers or interpreters may report a syntax error."},{"Start":"00:16.215 ","End":"00:19.380","Text":"What we\u0027re really trying to probe here is whether you"},{"Start":"00:19.380 ","End":"00:23.130","Text":"really understand what a syntax error actually is."},{"Start":"00:23.130 ","End":"00:25.500","Text":"The first part, we could say,"},{"Start":"00:25.500 ","End":"00:30.360","Text":"is that these errors can be picked up in advance of the program running,"},{"Start":"00:30.360 ","End":"00:33.360","Text":"and that\u0027s true for compilers and interpreters."},{"Start":"00:33.360 ","End":"00:36.270","Text":"However, for compilers, it\u0027s a little bit more obvious, I guess,"},{"Start":"00:36.270 ","End":"00:41.630","Text":"because the compiler has to translate the entire thing in one go,"},{"Start":"00:41.630 ","End":"00:44.780","Text":"the entire source code into machine code."},{"Start":"00:44.780 ","End":"00:49.640","Text":"So clearly, if it comes across any lines that it cannot make sense of,"},{"Start":"00:49.640 ","End":"00:51.460","Text":"it\u0027s going to report the error,"},{"Start":"00:51.460 ","End":"00:55.295","Text":"and no machine code is actually going to be produced at all."},{"Start":"00:55.295 ","End":"00:58.520","Text":"Whereas an interpreter would also do this,"},{"Start":"00:58.520 ","End":"01:00.110","Text":"but it does it line by line,"},{"Start":"01:00.110 ","End":"01:03.230","Text":"and it picks up those syntax errors as they are"},{"Start":"01:03.230 ","End":"01:07.820","Text":"encountered whilst the interpreter is trying to translate them into machine code."},{"Start":"01:07.820 ","End":"01:10.430","Text":"For a interpreted language,"},{"Start":"01:10.430 ","End":"01:13.370","Text":"the error occurs whilst the program\u0027s running and it"},{"Start":"01:13.370 ","End":"01:16.880","Text":"gets reported and the program then stops."},{"Start":"01:16.880 ","End":"01:18.440","Text":"Whereas in a compiler,"},{"Start":"01:18.440 ","End":"01:20.270","Text":"you would never have got to that stage."},{"Start":"01:20.270 ","End":"01:22.160","Text":"So for both of them,"},{"Start":"01:22.160 ","End":"01:25.370","Text":"you can actually check these types of error in advance."},{"Start":"01:25.370 ","End":"01:28.804","Text":"Although interpreted languages are not compiled,"},{"Start":"01:28.804 ","End":"01:32.570","Text":"they can have a compilation process run on them by"},{"Start":"01:32.570 ","End":"01:36.305","Text":"something called a pre-processor or syntax checker,"},{"Start":"01:36.305 ","End":"01:40.955","Text":"and they often run inside the editors for a programming language."},{"Start":"01:40.955 ","End":"01:44.150","Text":"JavaScript has quite a few pre-processes that will check"},{"Start":"01:44.150 ","End":"01:48.275","Text":"the syntax of the statements that are in the script,"},{"Start":"01:48.275 ","End":"01:51.170","Text":"and they can catch errors before you ever actually"},{"Start":"01:51.170 ","End":"01:54.395","Text":"try and launch the web page that contains that script."},{"Start":"01:54.395 ","End":"01:58.520","Text":"It is possible to check certain types of error in advance,"},{"Start":"01:58.520 ","End":"02:04.550","Text":"and that\u0027s why really compile time error is a fairly reasonable way to"},{"Start":"02:04.550 ","End":"02:07.565","Text":"describe this type of syntax error because"},{"Start":"02:07.565 ","End":"02:11.135","Text":"you can know about it in advance before the program ever runs,"},{"Start":"02:11.135 ","End":"02:12.905","Text":"and therefore, you can pick it up."},{"Start":"02:12.905 ","End":"02:15.290","Text":"That\u0027s the first part of the answer."},{"Start":"02:15.290 ","End":"02:19.640","Text":"The second one is talking about this term, syntax error,"},{"Start":"02:19.640 ","End":"02:22.850","Text":"is sometimes used to describe a different type of error,"},{"Start":"02:22.850 ","End":"02:26.135","Text":"and why is this strictly not correct?"},{"Start":"02:26.135 ","End":"02:30.020","Text":"Well, if the compiler or the interpreter can\u0027t"},{"Start":"02:30.020 ","End":"02:35.915","Text":"understand the meaning of something that is syntactically correct."},{"Start":"02:35.915 ","End":"02:38.915","Text":"That\u0027s a thing, it will have an error."},{"Start":"02:38.915 ","End":"02:41.690","Text":"It can\u0027t translate the expression into"},{"Start":"02:41.690 ","End":"02:44.390","Text":"machine code instructions and that will stop compilation,"},{"Start":"02:44.390 ","End":"02:46.520","Text":"or if it\u0027s an interpreted language,"},{"Start":"02:46.520 ","End":"02:49.085","Text":"it will stop execution and report an error."},{"Start":"02:49.085 ","End":"02:52.220","Text":"But actually, that type of error is not really a syntax error,"},{"Start":"02:52.220 ","End":"02:57.170","Text":"it\u0027s a semantic error because it can\u0027t understand the meaning of an expression."},{"Start":"02:57.170 ","End":"02:58.790","Text":"An example there would be,"},{"Start":"02:58.790 ","End":"03:01.670","Text":"if we had an expression and a line of code"},{"Start":"03:01.670 ","End":"03:05.435","Text":"that wasn\u0027t stored in a variable or was an output,"},{"Start":"03:05.435 ","End":"03:08.405","Text":"the compiler or the interpreter just doesn\u0027t know what to do with it,"},{"Start":"03:08.405 ","End":"03:11.540","Text":"even though the syntax for the expression is correct."},{"Start":"03:11.540 ","End":"03:14.390","Text":"It doesn\u0027t actually understand what the meaning of that would be,"},{"Start":"03:14.390 ","End":"03:15.995","Text":"what the purpose of it would be."},{"Start":"03:15.995 ","End":"03:17.645","Text":"It report it as an error,"},{"Start":"03:17.645 ","End":"03:20.510","Text":"and programmers would tend to call that a syntax error,"},{"Start":"03:20.510 ","End":"03:22.790","Text":"but it\u0027s not really a syntax error strictly speaking,"},{"Start":"03:22.790 ","End":"03:25.760","Text":"it\u0027s a semantic error as we learned previously."},{"Start":"03:25.760 ","End":"03:30.200","Text":"Semantics has to do with meaning rather than blind structure."},{"Start":"03:30.200 ","End":"03:34.870","Text":"That\u0027s really all we\u0027re looking for in this answer here,"},{"Start":"03:34.870 ","End":"03:37.250","Text":"is really finding out that"},{"Start":"03:37.250 ","End":"03:39.860","Text":"a syntax error is something that can be"},{"Start":"03:39.860 ","End":"03:42.740","Text":"picked up at a compile time for compiled languages."},{"Start":"03:42.740 ","End":"03:44.240","Text":"But if we wanted to,"},{"Start":"03:44.240 ","End":"03:47.960","Text":"we could also do it for interpreted languages through pre-processor."},{"Start":"03:47.960 ","End":"03:51.920","Text":"But we even use it as a catch-all for semantic errors sometimes as well,"},{"Start":"03:51.920 ","End":"03:53.780","Text":"and that\u0027s not strictly correct."},{"Start":"03:53.780 ","End":"03:57.290","Text":"That\u0027s the real-world. That\u0027s what programmers will talk about."},{"Start":"03:57.290 ","End":"03:58.950","Text":"That\u0027s it for this exercise."},{"Start":"03:58.950 ","End":"04:02.070","Text":"Thanks very much for watching and I\u0027ll see you in the next one."}],"ID":28020},{"Watched":false,"Name":"Exercise 4","Duration":"5m 23s","ChapterTopicVideoID":26925,"CourseChapterTopicPlaylistID":237668,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.270","Text":"Hi everyone. In this exercise,"},{"Start":"00:03.270 ","End":"00:05.580","Text":"we\u0027re being asked about other types of error other"},{"Start":"00:05.580 ","End":"00:07.988","Text":"than syntax errors because they\u0027re not the only type of errors,"},{"Start":"00:07.988 ","End":"00:09.450","Text":"it says in the question."},{"Start":"00:09.450 ","End":"00:13.005","Text":"We\u0027re being asked in part a why it\u0027s not possible to pick up"},{"Start":"00:13.005 ","End":"00:16.710","Text":"run-time errors in advance of the program being run."},{"Start":"00:16.710 ","End":"00:18.975","Text":"To answer this, we need to really say what"},{"Start":"00:18.975 ","End":"00:23.880","Text":"a run-time error is and compare it to syntax errors."},{"Start":"00:23.880 ","End":"00:27.150","Text":"Syntax and semantic errors are picked up in advance,"},{"Start":"00:27.150 ","End":"00:29.400","Text":"the program being run by the compiler or"},{"Start":"00:29.400 ","End":"00:32.640","Text":"the interpreter or pre-processor of the interpreter."},{"Start":"00:32.640 ","End":"00:35.520","Text":"But run-time errors can only be discovered once the"},{"Start":"00:35.520 ","End":"00:38.810","Text":"program\u0027s running because, by definition,"},{"Start":"00:38.810 ","End":"00:42.020","Text":"run-time errors have some dependency"},{"Start":"00:42.020 ","End":"00:45.500","Text":"that\u0027s external to the actual lines of code being executed."},{"Start":"00:45.500 ","End":"00:49.430","Text":"An example of that would be if a program was trying to open"},{"Start":"00:49.430 ","End":"00:53.420","Text":"a file and before it access the file,"},{"Start":"00:53.420 ","End":"00:55.729","Text":"that file got deleted or moved,"},{"Start":"00:55.729 ","End":"00:58.220","Text":"then at that point,"},{"Start":"00:58.220 ","End":"01:00.635","Text":"a run-time error will be reported."},{"Start":"01:00.635 ","End":"01:05.705","Text":"It couldn\u0027t ever know a compile-time that the file\u0027s there or not."},{"Start":"01:05.705 ","End":"01:09.320","Text":"Because even when the program runs, it might be there,"},{"Start":"01:09.320 ","End":"01:11.314","Text":"but it might be moved or deleted,"},{"Start":"01:11.314 ","End":"01:13.270","Text":"a microsecond before it\u0027s access,"},{"Start":"01:13.270 ","End":"01:17.410","Text":"so even if it did exist at one point it\u0027s when trying"},{"Start":"01:17.410 ","End":"01:22.295","Text":"to be accessed that it would generate an error if the file wasn\u0027t there."},{"Start":"01:22.295 ","End":"01:27.370","Text":"You cannot pick up a run-time error in advance of the program being run."},{"Start":"01:27.370 ","End":"01:31.550","Text":"The second part of this is asking about the other type of error,"},{"Start":"01:31.550 ","End":"01:33.485","Text":"which is logical errors."},{"Start":"01:33.485 ","End":"01:35.840","Text":"Why is it that experienced programmers spend"},{"Start":"01:35.840 ","End":"01:38.900","Text":"more time dealing with logical errors than syntax errors?"},{"Start":"01:38.900 ","End":"01:40.730","Text":"What is a logical error?"},{"Start":"01:40.730 ","End":"01:45.290","Text":"It\u0027s one where you can actually run the program because"},{"Start":"01:45.290 ","End":"01:49.790","Text":"there\u0027s no syntax errors and it also doesn\u0027t produce a run-time error either."},{"Start":"01:49.790 ","End":"01:51.620","Text":"It just doesn\u0027t do what it\u0027s supposed to do,"},{"Start":"01:51.620 ","End":"01:53.630","Text":"it doesn\u0027t produce the intended outcome."},{"Start":"01:53.630 ","End":"01:56.930","Text":"Logical errors tend to be more difficult to"},{"Start":"01:56.930 ","End":"02:00.590","Text":"track down and resolve whereas syntax errors are usually"},{"Start":"02:00.590 ","End":"02:04.019","Text":"very simple things that are the result of typing errors"},{"Start":"02:04.019 ","End":"02:08.210","Text":"or for beginners that doesn\u0027t understand the syntax exactly."},{"Start":"02:08.210 ","End":"02:11.765","Text":"You\u0027re obviously going to encounter those more frequently"},{"Start":"02:11.765 ","End":"02:15.635","Text":"when you\u0027re starting out and you\u0027ll have those less and less over time."},{"Start":"02:15.635 ","End":"02:20.720","Text":"Whereas any reasonably complex program just running first-time,"},{"Start":"02:20.720 ","End":"02:22.910","Text":"it\u0027s very unlikely that that would happen,"},{"Start":"02:22.910 ","End":"02:25.760","Text":"even if it does seem to work first-time round."},{"Start":"02:25.760 ","End":"02:28.955","Text":"It might work with some inputs but fail with others."},{"Start":"02:28.955 ","End":"02:31.190","Text":"Or it might work when it\u0027s in a particular state,"},{"Start":"02:31.190 ","End":"02:33.095","Text":"but not in another state."},{"Start":"02:33.095 ","End":"02:38.360","Text":"Even very experienced programmers have to keep testing and refining"},{"Start":"02:38.360 ","End":"02:45.340","Text":"their code until it produces the expected results under all possible circumstances."},{"Start":"02:45.340 ","End":"02:48.800","Text":"That\u0027s why logical errors are something that even"},{"Start":"02:48.800 ","End":"02:53.330","Text":"experienced programmer is going to spend quite a lot of time working on."},{"Start":"02:53.330 ","End":"02:58.250","Text":"The final part of this exercise is going a little bit more"},{"Start":"02:58.250 ","End":"03:00.800","Text":"into types of error just to"},{"Start":"03:00.800 ","End":"03:04.580","Text":"recognize whether which one of the errors that this one would be."},{"Start":"03:04.580 ","End":"03:08.855","Text":"It\u0027s talking about the amount of free memory available once the program"},{"Start":"03:08.855 ","End":"03:14.105","Text":"running can vary and what type of error that could cause and why."},{"Start":"03:14.105 ","End":"03:18.080","Text":"This comes back to the definition of a computer,"},{"Start":"03:18.080 ","End":"03:20.540","Text":"really lots of different types of computer"},{"Start":"03:20.540 ","End":"03:23.450","Text":"and the one that you\u0027re using is a personal computer,"},{"Start":"03:23.450 ","End":"03:26.960","Text":"there could be a computer embedded into some system like"},{"Start":"03:26.960 ","End":"03:31.144","Text":"a washing machine or a mobile phone is a computer."},{"Start":"03:31.144 ","End":"03:34.280","Text":"But for particularly personal computers,"},{"Start":"03:34.280 ","End":"03:36.290","Text":"memory availability is dependent on"},{"Start":"03:36.290 ","End":"03:39.110","Text":"what other programs are being run at any particular time."},{"Start":"03:39.110 ","End":"03:42.020","Text":"For example, they\u0027ll all have an operating system"},{"Start":"03:42.020 ","End":"03:46.070","Text":"and the operating system itself might be running a virus scan in the background."},{"Start":"03:46.070 ","End":"03:50.885","Text":"Or the user might be using some word processing software or playing some music."},{"Start":"03:50.885 ","End":"03:54.620","Text":"All of those programs are going to use memory,"},{"Start":"03:54.620 ","End":"03:59.390","Text":"so we can\u0027t know how much memory is available until we are actually"},{"Start":"03:59.390 ","End":"04:01.760","Text":"running the program which will give you a hint as to"},{"Start":"04:01.760 ","End":"04:04.745","Text":"the answer because if you launch another program,"},{"Start":"04:04.745 ","End":"04:07.670","Text":"it might load, but then whilst it\u0027s running,"},{"Start":"04:07.670 ","End":"04:10.610","Text":"it might request some memory to store its own data."},{"Start":"04:10.610 ","End":"04:14.885","Text":"That\u0027s in fact, quite a common thing in most programming languages."},{"Start":"04:14.885 ","End":"04:18.905","Text":"Therefore, that amount of memory might not be available"},{"Start":"04:18.905 ","End":"04:23.060","Text":"and it would generate a run-time error just like the file error we saw earlier,"},{"Start":"04:23.060 ","End":"04:26.075","Text":"you can\u0027t know how much memory is going to be available"},{"Start":"04:26.075 ","End":"04:30.320","Text":"because that can vary depending on what the circumstances are."},{"Start":"04:30.320 ","End":"04:34.085","Text":"The only way you will really know is when you\u0027re requesting the memory,"},{"Start":"04:34.085 ","End":"04:36.260","Text":"you will know whether there\u0027s enough memory or not."},{"Start":"04:36.260 ","End":"04:40.145","Text":"If there isn\u0027t, it will generate a run-time error and"},{"Start":"04:40.145 ","End":"04:44.705","Text":"your program may crash or it may report an error."},{"Start":"04:44.705 ","End":"04:47.495","Text":"It depends on how your program is written and in what language."},{"Start":"04:47.495 ","End":"04:50.060","Text":"But that would be a run-time error."},{"Start":"04:50.060 ","End":"04:56.765","Text":"That\u0027s distinct from a logical error or from a syntax error as we\u0027ve talked about before."},{"Start":"04:56.765 ","End":"05:00.770","Text":"That\u0027s it for all the exercises in this topic actually."},{"Start":"05:00.770 ","End":"05:05.615","Text":"It sets us up nicely for beginning to write some programs of our own."},{"Start":"05:05.615 ","End":"05:10.160","Text":"The first point really was to understand what errors we\u0027re encountering,"},{"Start":"05:10.160 ","End":"05:11.750","Text":"to manage our frustrations,"},{"Start":"05:11.750 ","End":"05:15.545","Text":"and to understand why they\u0027re happening and what specific"},{"Start":"05:15.545 ","End":"05:20.090","Text":"error category you\u0027re dealing with when you come across a problem."},{"Start":"05:20.090 ","End":"05:22.370","Text":"I\u0027ll see you in the next chapter."},{"Start":"05:22.370 ","End":"05:24.450","Text":"Thanks very much for watching."}],"ID":28021}],"Thumbnail":null,"ID":237668},{"Name":"Variables and primitive data types","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Variables and datatypes","Duration":"16m 4s","ChapterTopicVideoID":25528,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.170 ","End":"00:05.700","Text":"Welcome everybody to this video in which we will learn how to define"},{"Start":"00:05.700 ","End":"00:10.349","Text":"the term variable to select an appropriate datatype for a variable."},{"Start":"00:10.349 ","End":"00:14.490","Text":"To create variables and store or change values in them and create"},{"Start":"00:14.490 ","End":"00:18.885","Text":"a basic program in which you can declare variables and output layer contents."},{"Start":"00:18.885 ","End":"00:21.540","Text":"The title of a classic computer science book is"},{"Start":"00:21.540 ","End":"00:25.875","Text":"Algorithms Plus Data Structures Equals Programs."},{"Start":"00:25.875 ","End":"00:28.320","Text":"Is actually a really clever title because what it"},{"Start":"00:28.320 ","End":"00:31.770","Text":"essentially says is that you can take a set of instructions,"},{"Start":"00:31.770 ","End":"00:34.650","Text":"apply them to store data and"},{"Start":"00:34.650 ","End":"00:39.040","Text":"the resulting interaction of instructions with the data is a program."},{"Start":"00:39.040 ","End":"00:43.700","Text":"The data structures mentioned in the book title are a variety of methods for storing,"},{"Start":"00:43.700 ","End":"00:46.445","Text":"modifying, and retrieving datary memory."},{"Start":"00:46.445 ","End":"00:48.920","Text":"Commonly, these data items being stored in"},{"Start":"00:48.920 ","End":"00:52.445","Text":"the data structure are related to the other items in some way."},{"Start":"00:52.445 ","End":"00:55.580","Text":"For example, we could store the marks for 8 students in"},{"Start":"00:55.580 ","End":"00:59.060","Text":"a class in a data structure called an array."},{"Start":"00:59.060 ","End":"01:02.075","Text":"But for a single item of data being stored,"},{"Start":"01:02.075 ","End":"01:06.200","Text":"which is not directly related to or grouped with anything else,"},{"Start":"01:06.200 ","End":"01:09.935","Text":"we can simply store it in a single memory location."},{"Start":"01:09.935 ","End":"01:12.935","Text":"Memory is labeled sequentially,"},{"Start":"01:12.935 ","End":"01:17.015","Text":"numbering each individual memory location starting from"},{"Start":"01:17.015 ","End":"01:22.610","Text":"0 and we call each memory location a memory address."},{"Start":"01:22.610 ","End":"01:25.880","Text":"Any individual memory location can be used to"},{"Start":"01:25.880 ","End":"01:29.570","Text":"store a single value at particular instance in time."},{"Start":"01:29.570 ","End":"01:32.870","Text":"In assembly language or a high-level language,"},{"Start":"01:32.870 ","End":"01:35.920","Text":"we\u0027d also give the memory location a name,"},{"Start":"01:35.920 ","End":"01:38.825","Text":"so that when we subsequently you want to read back the stored value,"},{"Start":"01:38.825 ","End":"01:41.585","Text":"or if we wanted to change the stored value to something else,"},{"Start":"01:41.585 ","End":"01:45.065","Text":"we use the name to refer to that specific memory location."},{"Start":"01:45.065 ","End":"01:47.660","Text":"We can now define the term variable."},{"Start":"01:47.660 ","End":"01:50.690","Text":"It\u0027s a named memory location used to"},{"Start":"01:50.690 ","End":"01:53.975","Text":"store data which can change while a program is being executed."},{"Start":"01:53.975 ","End":"01:57.355","Text":"Alongside this definition, let\u0027s also define a related term."},{"Start":"01:57.355 ","End":"02:00.665","Text":"Programmed state, sometimes just called state,"},{"Start":"02:00.665 ","End":"02:05.780","Text":"is the contents of variables at any particular point in the execution of a program."},{"Start":"02:05.780 ","End":"02:10.655","Text":"A fundamental idea in imperative programming languages is the concept of state."},{"Start":"02:10.655 ","End":"02:15.620","Text":"Variables are used to store data in memory and the contents of those variables at"},{"Start":"02:15.620 ","End":"02:17.960","Text":"any particular point in the execution of"},{"Start":"02:17.960 ","End":"02:21.685","Text":"the program are set to describe the state of the program."},{"Start":"02:21.685 ","End":"02:26.960","Text":"Instructions that are carried out by the CPU have the effect of changing the state of"},{"Start":"02:26.960 ","End":"02:33.020","Text":"the program as data is stored or changed in memory locations being used as variables."},{"Start":"02:33.020 ","End":"02:37.710","Text":"For example, we might want to represent the state of a program using 2 variables."},{"Start":"02:37.710 ","End":"02:40.790","Text":"One of which contains a count, and the other,"},{"Start":"02:40.790 ","End":"02:46.130","Text":"which contains the value false unless the count has reached 3."},{"Start":"02:46.130 ","End":"02:50.840","Text":"As you can see, the initial value of the start of the program is false for"},{"Start":"02:50.840 ","End":"02:55.280","Text":"it\u0027s finished and 0 for intCount."},{"Start":"02:55.280 ","End":"02:57.080","Text":"As the program progresses,"},{"Start":"02:57.080 ","End":"03:00.420","Text":"intCount goes up to 1 and then 2,"},{"Start":"03:00.420 ","End":"03:02.960","Text":"and then 3 and finally,"},{"Start":"03:02.960 ","End":"03:07.030","Text":"the conditions have been met so is finished turns to true."},{"Start":"03:07.030 ","End":"03:10.040","Text":"Because CPU hardware is designed around the ability"},{"Start":"03:10.040 ","End":"03:13.235","Text":"to carry out instructions which modify memory locations,"},{"Start":"03:13.235 ","End":"03:18.835","Text":"most high-level programming languages follow this imperative style."},{"Start":"03:18.835 ","End":"03:21.950","Text":"Now we\u0027ve established what a variable is and its purpose."},{"Start":"03:21.950 ","End":"03:24.500","Text":"Let\u0027s go a little bit deeper into the practical use of"},{"Start":"03:24.500 ","End":"03:28.505","Text":"variables by looking at the types of data that can be stored in a variable."},{"Start":"03:28.505 ","End":"03:31.130","Text":"A datatype is a property of variables that"},{"Start":"03:31.130 ","End":"03:34.145","Text":"determines how stored data should be interpreted,"},{"Start":"03:34.145 ","End":"03:37.340","Text":"constrained, and used in expressions,"},{"Start":"03:37.340 ","End":"03:38.645","Text":"as we\u0027ve seen previously,"},{"Start":"03:38.645 ","End":"03:42.485","Text":"a binary value in the memory of a computer can be interpreted in many ways."},{"Start":"03:42.485 ","End":"03:46.310","Text":"It could represent a machine code instruction and its data,"},{"Start":"03:46.310 ","End":"03:51.155","Text":"where here is the instruction and here\u0027s the data it\u0027s operating on."},{"Start":"03:51.155 ","End":"03:55.280","Text":"In fact, it\u0027s the very same instruction that we saw earlier,"},{"Start":"03:55.280 ","End":"04:00.005","Text":"which adds 5 to a previously held value in the CPU."},{"Start":"04:00.005 ","End":"04:04.220","Text":"Or it could represent a 2\u0027s compliment 16-bit integer,"},{"Start":"04:04.220 ","End":"04:11.920","Text":"which works out to be the value minus 14,843 in this case."},{"Start":"04:11.920 ","End":"04:15.350","Text":"It might instead represent a floating point number with"},{"Start":"04:15.350 ","End":"04:21.550","Text":"a 4-bit 2\u0027s compliment exponent in the lower 4-bits and at 12 bit."},{"Start":"04:21.550 ","End":"04:24.815","Text":"Two\u0027s complement mantissa, in which case,"},{"Start":"04:24.815 ","End":"04:29.795","Text":"it would represent the decimal number minus 14.5."},{"Start":"04:29.795 ","End":"04:33.500","Text":"It could even represent a single Unicode character,"},{"Start":"04:33.500 ","End":"04:36.200","Text":"which in hex would be this value and would"},{"Start":"04:36.200 ","End":"04:39.634","Text":"actually give us a symbol in the Korean alphabet,"},{"Start":"04:39.634 ","End":"04:41.240","Text":"which looks like this."},{"Start":"04:41.240 ","End":"04:46.550","Text":"What a bit pattern represents depends on how we choose to interpret that bit pattern."},{"Start":"04:46.550 ","End":"04:48.540","Text":"In a typical high-level language program,"},{"Start":"04:48.540 ","End":"04:50.000","Text":"when creating a variable,"},{"Start":"04:50.000 ","End":"04:52.580","Text":"you will state the name and also specify"},{"Start":"04:52.580 ","End":"04:55.565","Text":"what type of data will be stored in the variable."},{"Start":"04:55.565 ","End":"04:59.960","Text":"In this case, with defining a variable called my number,"},{"Start":"04:59.960 ","End":"05:03.620","Text":"that\u0027s the identifier and its datatype is integer."},{"Start":"05:03.620 ","End":"05:07.145","Text":"The variables datatype determines what we can and can\u0027t do with it."},{"Start":"05:07.145 ","End":"05:10.430","Text":"For example, an integer can be added to"},{"Start":"05:10.430 ","End":"05:14.570","Text":"another integer to produce the sum of the 2 integers."},{"Start":"05:14.570 ","End":"05:22.565","Text":"Or we could divide an integer by another integer and we\u0027d get the result 5 in this case."},{"Start":"05:22.565 ","End":"05:25.140","Text":"However, if we chose to divide"},{"Start":"05:25.240 ","End":"05:30.740","Text":"1 integer by another and the result was not a whole number,"},{"Start":"05:30.740 ","End":"05:36.020","Text":"we could not store the result accurately inside another integer variable."},{"Start":"05:36.020 ","End":"05:37.895","Text":"We\u0027d lose the fractional part."},{"Start":"05:37.895 ","End":"05:40.415","Text":"In this case, the 0.5."},{"Start":"05:40.415 ","End":"05:47.005","Text":"This was an implication of the original decision to make a variable an integer datatype."},{"Start":"05:47.005 ","End":"05:49.790","Text":"Some data types can allow you to choose between"},{"Start":"05:49.790 ","End":"05:53.480","Text":"several related types which vary in their size or precision."},{"Start":"05:53.480 ","End":"05:55.865","Text":"For example, if storing a number,"},{"Start":"05:55.865 ","End":"05:58.490","Text":"we could store it as an 8-bit integer,"},{"Start":"05:58.490 ","End":"06:02.840","Text":"a 16-bit integer, a 32-bit integer,"},{"Start":"06:02.840 ","End":"06:05.090","Text":"or a 64-bit integer."},{"Start":"06:05.090 ","End":"06:08.270","Text":"Each of these would be a different datatype and the range"},{"Start":"06:08.270 ","End":"06:11.600","Text":"of numbers we could store would vary depending on the type."},{"Start":"06:11.600 ","End":"06:14.450","Text":"Different high-level languages may differ in the number of"},{"Start":"06:14.450 ","End":"06:17.885","Text":"bits that a particular datatype occupies in memory."},{"Start":"06:17.885 ","End":"06:20.180","Text":"These examples of a Java,"},{"Start":"06:20.180 ","End":"06:22.160","Text":"but in the C programming language,"},{"Start":"06:22.160 ","End":"06:27.185","Text":"and int could be 16-bits on 1 system and 32-bits on another."},{"Start":"06:27.185 ","End":"06:30.380","Text":"The programmer is responsible for making sure they take account"},{"Start":"06:30.380 ","End":"06:33.820","Text":"of this when writing code in such languages."},{"Start":"06:33.820 ","End":"06:38.090","Text":"Most current computer systems use memory locations that are 16,"},{"Start":"06:38.090 ","End":"06:41.165","Text":"32 or 64-bits in size."},{"Start":"06:41.165 ","End":"06:43.625","Text":"If you\u0027re storing a single byte of data,"},{"Start":"06:43.625 ","End":"06:48.425","Text":"you could fit 2 bytes into a single 16-bit memory location,"},{"Start":"06:48.425 ","End":"06:52.085","Text":"or 4 bytes in a 32-bit memory location."},{"Start":"06:52.085 ","End":"06:57.095","Text":"Selecting data types for the variables which store numbers can require some thought."},{"Start":"06:57.095 ","End":"06:59.720","Text":"It\u0027s more efficient in terms of memory used to store"},{"Start":"06:59.720 ","End":"07:02.990","Text":"the numbers in the smallest datatype possible."},{"Start":"07:02.990 ","End":"07:07.175","Text":"For example, say we wanted to restore someone\u0027s age in a variable,"},{"Start":"07:07.175 ","End":"07:11.435","Text":"the oldest recorded verified human age is 122 years."},{"Start":"07:11.435 ","End":"07:14.810","Text":"If we wanted to store the age in years of a human,"},{"Start":"07:14.810 ","End":"07:21.215","Text":"we can fit that into 7 bits because 7 bits will allow us to store a number up to a 127."},{"Start":"07:21.215 ","End":"07:23.360","Text":"You could argue that there\u0027s no point in using"},{"Start":"07:23.360 ","End":"07:25.655","Text":"a larger amount of memory for the age variable."},{"Start":"07:25.655 ","End":"07:28.610","Text":"There\u0027d also be no point in storing a negative number in"},{"Start":"07:28.610 ","End":"07:32.530","Text":"the age variable as no human can have a negative age."},{"Start":"07:32.530 ","End":"07:36.500","Text":"A suitable datatype for the age variable would be a byte,"},{"Start":"07:36.500 ","End":"07:39.020","Text":"or even better for languages that support it,"},{"Start":"07:39.020 ","End":"07:43.812","Text":"an unsigned byte, which would give us a range from 0-255."},{"Start":"07:43.812 ","End":"07:48.380","Text":"Other numeric data types can contain floating point numbers,"},{"Start":"07:48.380 ","End":"07:51.185","Text":"that\u0027s numbers that have a fractional component."},{"Start":"07:51.185 ","End":"07:53.900","Text":"We call these real numbers or reals."},{"Start":"07:53.900 ","End":"07:56.390","Text":"Once again, these come in sizes so the choice"},{"Start":"07:56.390 ","End":"07:58.850","Text":"is more limited and in fact comprises just 2;"},{"Start":"07:58.850 ","End":"08:01.400","Text":"the float data type and the double data type."},{"Start":"08:01.400 ","End":"08:04.535","Text":"Here we\u0027re more interested in the precision of the number,"},{"Start":"08:04.535 ","End":"08:07.130","Text":"not necessarily the magnitude of the number."},{"Start":"08:07.130 ","End":"08:09.815","Text":"A double can store a larger number than the float,"},{"Start":"08:09.815 ","End":"08:13.700","Text":"but it can also store the fractional part with more decimal places."},{"Start":"08:13.700 ","End":"08:18.470","Text":"The numbers here have been written in scientific notation because they"},{"Start":"08:18.470 ","End":"08:20.300","Text":"had so many digits they wouldn\u0027t fit on"},{"Start":"08:20.300 ","End":"08:23.255","Text":"the screen and they can be quite hard to get your head around."},{"Start":"08:23.255 ","End":"08:28.250","Text":"To spell it out, the smallest number that can be represented by a float in Java has"},{"Start":"08:28.250 ","End":"08:33.230","Text":"44 zeros between the decimal point and the digits 14,"},{"Start":"08:33.230 ","End":"08:40.295","Text":"for a double, there are 323 zeros between the decimal point and the digits 49."},{"Start":"08:40.295 ","End":"08:44.015","Text":"Other data types can be used to store data that is not numerical."},{"Start":"08:44.015 ","End":"08:48.140","Text":"A character data type can be used to store a single character,"},{"Start":"08:48.140 ","End":"08:50.390","Text":"which is a symbol that can be typed or output"},{"Start":"08:50.390 ","End":"08:52.535","Text":"by the system and belongs to a character set."},{"Start":"08:52.535 ","End":"08:58.445","Text":"The amount of memory one character uses can be anything from 7 bits to 32 bits in size."},{"Start":"08:58.445 ","End":"09:02.930","Text":"The exact size is dependent on the programming language and the system is running"},{"Start":"09:02.930 ","End":"09:05.420","Text":"on how many bits are available for the character"},{"Start":"09:05.420 ","End":"09:08.105","Text":"determines what symbols can be displayed."},{"Start":"09:08.105 ","End":"09:14.180","Text":"Ascii encodings can only encode English or Western European characters."},{"Start":"09:14.180 ","End":"09:17.750","Text":"Unicode encoding such as UTF-8, 16,"},{"Start":"09:17.750 ","End":"09:22.355","Text":"or 32 allow characters from any languages to be stored."},{"Start":"09:22.355 ","End":"09:26.330","Text":"Characters can be strung together to form another datatype called a string."},{"Start":"09:26.330 ","End":"09:30.020","Text":"These are used to hold sequences of characters that could, for example,"},{"Start":"09:30.020 ","End":"09:34.325","Text":"represent words, names, sentences, or messages."},{"Start":"09:34.325 ","End":"09:35.810","Text":"In most programming languages,"},{"Start":"09:35.810 ","End":"09:38.270","Text":"strings are not classed as primitive data types,"},{"Start":"09:38.270 ","End":"09:41.435","Text":"but as composite or compound data types."},{"Start":"09:41.435 ","End":"09:46.309","Text":"That means they\u0027re constructed using primitive data types and other data structures."},{"Start":"09:46.309 ","End":"09:47.810","Text":"In the case of the string,"},{"Start":"09:47.810 ","End":"09:53.210","Text":"it\u0027s most commonly a composite using characters and a data structure called an array."},{"Start":"09:53.210 ","End":"09:56.390","Text":"We\u0027ll cover strings and arrays in detail later in the course."},{"Start":"09:56.390 ","End":"09:59.165","Text":"The final primitive datatype is the Boolean,"},{"Start":"09:59.165 ","End":"10:01.850","Text":"which can only contain 1 of 2 different values,"},{"Start":"10:01.850 ","End":"10:04.939","Text":"and therefore requires only a single bit of memory for storage."},{"Start":"10:04.939 ","End":"10:07.595","Text":"The bit is either 1 or 0."},{"Start":"10:07.595 ","End":"10:11.180","Text":"We interpret the value as either true or false."},{"Start":"10:11.180 ","End":"10:13.160","Text":"Whilst this might seem limiting,"},{"Start":"10:13.160 ","End":"10:15.260","Text":"Boolean variables are commonly used to provide"},{"Start":"10:15.260 ","End":"10:18.075","Text":"a signal from one part of the program to another."},{"Start":"10:18.075 ","End":"10:19.780","Text":"The signal is known as a flag."},{"Start":"10:19.780 ","End":"10:20.950","Text":"You think of a car race."},{"Start":"10:20.950 ","End":"10:23.500","Text":"The first car to complete the race is signaled with"},{"Start":"10:23.500 ","End":"10:28.140","Text":"a checkered flag being raised and waved about to signify that there is a winner."},{"Start":"10:28.140 ","End":"10:30.470","Text":"In a program, we might signal from one part of"},{"Start":"10:30.470 ","End":"10:33.260","Text":"the program to another part when some process"},{"Start":"10:33.260 ","End":"10:39.050","Text":"completes or we might set a flag to indicate whether some input data is valid or not."},{"Start":"10:39.050 ","End":"10:44.435","Text":"Or we might allow someone a second and final try to answer a question in a quiz."},{"Start":"10:44.435 ","End":"10:47.345","Text":"We need to know whether this is a first trial or not."},{"Start":"10:47.345 ","End":"10:50.630","Text":"All of these would be examples where we might use a flag variable."},{"Start":"10:50.630 ","End":"10:51.995","Text":"Variables need to have a name,"},{"Start":"10:51.995 ","End":"10:54.230","Text":"more formerly known as an identifier."},{"Start":"10:54.230 ","End":"10:56.389","Text":"There are rules around what constitutes"},{"Start":"10:56.389 ","End":"10:59.540","Text":"a valid identifier and also conventions that we should know about,"},{"Start":"10:59.540 ","End":"11:03.935","Text":"which make it easier to work with other programmers who adopt the same conventions."},{"Start":"11:03.935 ","End":"11:08.990","Text":"Most languages have very similar rules about what is and isn\u0027t allowed in an identifier."},{"Start":"11:08.990 ","End":"11:11.420","Text":"An identifier that is not valuable result in"},{"Start":"11:11.420 ","End":"11:15.680","Text":"a compile-time error or a syntax error in an interpreted language."},{"Start":"11:15.680 ","End":"11:18.380","Text":"Most generally the identifier can use"},{"Start":"11:18.380 ","End":"11:22.874","Text":"upper or lowercase characters in the ascii character set."},{"Start":"11:22.874 ","End":"11:27.080","Text":"Variables called myvariable, all in capitals."},{"Start":"11:27.080 ","End":"11:30.530","Text":"Myvariable with a M and V,"},{"Start":"11:30.530 ","End":"11:35.615","Text":"or myvariable with just the V are all valid identifiers."},{"Start":"11:35.615 ","End":"11:39.440","Text":"A limited set of other characters can also be used in identifiers,"},{"Start":"11:39.440 ","End":"11:41.570","Text":"depending on the programming language."},{"Start":"11:41.570 ","End":"11:44.225","Text":"Digits are allowed in most languages,"},{"Start":"11:44.225 ","End":"11:47.360","Text":"the underscore is also allowed in most languages."},{"Start":"11:47.360 ","End":"11:49.910","Text":"The dollar sign is allowed in Java,"},{"Start":"11:49.910 ","End":"11:53.195","Text":"a single quote is allowed in Haskell,"},{"Start":"11:53.195 ","End":"11:55.880","Text":"and the hyphen is allowed in lisp."},{"Start":"11:55.880 ","End":"11:58.910","Text":"It might also be possible to use non ascii characters"},{"Start":"11:58.910 ","End":"12:02.060","Text":"in the identifier in some languages as well."},{"Start":"12:02.060 ","End":"12:04.865","Text":"For example, Python version 3"},{"Start":"12:04.865 ","End":"12:08.870","Text":"onwards allows characters from any language in the identifier."},{"Start":"12:08.870 ","End":"12:12.925","Text":"A big no in virtually every language is the use of the space character."},{"Start":"12:12.925 ","End":"12:16.030","Text":"This is not allowed in identifiers because it makes the job of"},{"Start":"12:16.030 ","End":"12:19.620","Text":"the compiler or interpreter significantly harder."},{"Start":"12:19.620 ","End":"12:24.050","Text":"The underscore character is often used as a way of breaking upwards instead."},{"Start":"12:24.050 ","End":"12:26.930","Text":"Other common restrictions include not allowing"},{"Start":"12:26.930 ","End":"12:29.645","Text":"numerical digits at the front of identifiers,"},{"Start":"12:29.645 ","End":"12:31.970","Text":"in this case, the number 2."},{"Start":"12:31.970 ","End":"12:38.210","Text":"Also not allowing keywords from a language to be used as an identifier in this case,"},{"Start":"12:38.210 ","End":"12:42.140","Text":"finally, is a keyword in the language Java,"},{"Start":"12:42.140 ","End":"12:45.680","Text":"so would not be allowed as an identifier in Java."},{"Start":"12:45.680 ","End":"12:48.320","Text":"In summary, to be safe,"},{"Start":"12:48.320 ","End":"12:50.630","Text":"when you\u0027re choosing an identifier,"},{"Start":"12:50.630 ","End":"12:53.660","Text":"only ever use upper and lowercase letters."},{"Start":"12:53.660 ","End":"12:55.670","Text":"In the ascii character set,"},{"Start":"12:55.670 ","End":"12:59.779","Text":"digits are fine unless they\u0027re used as the first character."},{"Start":"12:59.779 ","End":"13:04.850","Text":"An underscore should be used to separate words if we need it and that\u0027s fine and be aware"},{"Start":"13:04.850 ","End":"13:07.235","Text":"of and avoid using"},{"Start":"13:07.235 ","End":"13:11.225","Text":"any identifies that match keywords available in your programming language."},{"Start":"13:11.225 ","End":"13:13.520","Text":"Those previous rules are just that, rules."},{"Start":"13:13.520 ","End":"13:14.885","Text":"They must be obeyed."},{"Start":"13:14.885 ","End":"13:17.615","Text":"If they are broken, the compiler will complain"},{"Start":"13:17.615 ","End":"13:20.855","Text":"or the interpreter will stop with a syntax error message."},{"Start":"13:20.855 ","End":"13:23.390","Text":"Conventions are not rules but accepted ways of"},{"Start":"13:23.390 ","End":"13:26.000","Text":"behaving in a particular field or situation."},{"Start":"13:26.000 ","End":"13:28.160","Text":"A typical classroom convention, for example,"},{"Start":"13:28.160 ","End":"13:30.905","Text":"is that you put your hand up if you want the teacher\u0027s attention."},{"Start":"13:30.905 ","End":"13:33.995","Text":"Identifier\u0027s have their own conventions."},{"Start":"13:33.995 ","End":"13:37.940","Text":"You mentioned that you cannot use spaces in an identifier."},{"Start":"13:37.940 ","End":"13:39.305","Text":"As an alternative,"},{"Start":"13:39.305 ","End":"13:41.450","Text":"you can use the underscore character."},{"Start":"13:41.450 ","End":"13:46.670","Text":"Separating words with underscores makes the identifier easier and quicker to read."},{"Start":"13:46.670 ","End":"13:50.983","Text":"In this example, there are no spaces and no underscores,"},{"Start":"13:50.983 ","End":"13:53.765","Text":"so the words and then the identifier are difficult to see."},{"Start":"13:53.765 ","End":"13:56.570","Text":"Adding underscores as we\u0027ve done here and"},{"Start":"13:56.570 ","End":"14:00.695","Text":"here makes it much easier to read the words within the identifier."},{"Start":"14:00.695 ","End":"14:04.025","Text":"The name given to this naming style is snake case,"},{"Start":"14:04.025 ","End":"14:06.290","Text":"I guess because the underscore looks"},{"Start":"14:06.290 ","End":"14:08.630","Text":"like a snake slithering along the bottom of the word."},{"Start":"14:08.630 ","End":"14:11.390","Text":"However, the underscore character can be tricky to find on"},{"Start":"14:11.390 ","End":"14:15.620","Text":"some keyboards and usually requires the Shift key to be pressed as well."},{"Start":"14:15.620 ","End":"14:19.520","Text":"Programmers are lazy or highly efficient depending on your point of view."},{"Start":"14:19.520 ","End":"14:22.880","Text":"They\u0027d prefer to type as few characters as possible."},{"Start":"14:22.880 ","End":"14:28.385","Text":"Hence, CamelCase, where each new word starts with a capital letter,"},{"Start":"14:28.385 ","End":"14:30.365","Text":"is preferred by many programmers,"},{"Start":"14:30.365 ","End":"14:35.060","Text":"seen here with a capital H and a capital N. The name comes from these capital letters"},{"Start":"14:35.060 ","End":"14:40.490","Text":"standing out above the lowercase letters appearing as a hump,"},{"Start":"14:40.490 ","End":"14:42.425","Text":"as you might find on the back of a camel,"},{"Start":"14:42.425 ","End":"14:44.960","Text":"where you do capitalize the first letter as well."},{"Start":"14:44.960 ","End":"14:47.435","Text":"This is known as upper CamelCase,"},{"Start":"14:47.435 ","End":"14:50.285","Text":"or sometimes called PascalCase."},{"Start":"14:50.285 ","End":"14:52.550","Text":"The only difference with the one above here is"},{"Start":"14:52.550 ","End":"14:56.060","Text":"this first letter here is also capitalized."},{"Start":"14:56.060 ","End":"15:01.220","Text":"Most programmers don\u0027t use snake case except for in a very particular situation."},{"Start":"15:01.220 ","End":"15:04.310","Text":"There\u0027s a type of variable that only has its value set once in"},{"Start":"15:04.310 ","End":"15:09.320","Text":"the program and whose value does not subsequently change whilst the program is running."},{"Start":"15:09.320 ","End":"15:10.819","Text":"We call this a constant."},{"Start":"15:10.819 ","End":"15:14.000","Text":"By convention, constants are usually identified in"},{"Start":"15:14.000 ","End":"15:19.355","Text":"all uppercase letters with an underscore separating each word."},{"Start":"15:19.355 ","End":"15:22.190","Text":"This is called upper Snake case."},{"Start":"15:22.190 ","End":"15:23.870","Text":"In some other languages,"},{"Start":"15:23.870 ","End":"15:28.070","Text":"a symbol might conventionally signify some meaning to the reader of the code."},{"Start":"15:28.070 ","End":"15:32.660","Text":"For example, a single or double underscore in"},{"Start":"15:32.660 ","End":"15:37.280","Text":"Python programs might mark that identifier to be treated differently."},{"Start":"15:37.280 ","End":"15:40.565","Text":"For example, it might mark it as a private variable."},{"Start":"15:40.565 ","End":"15:44.600","Text":"Avoid using underscores as the first or last characters in"},{"Start":"15:44.600 ","End":"15:48.905","Text":"identifiers unless you\u0027re a Python programmer and you know what you\u0027re doing."},{"Start":"15:48.905 ","End":"15:51.380","Text":"That\u0027s it for this video,"},{"Start":"15:51.380 ","End":"15:54.365","Text":"in it we defined the term variable"},{"Start":"15:54.365 ","End":"15:58.025","Text":"and we selected an appropriate datatype for a variable."},{"Start":"15:58.025 ","End":"15:59.390","Text":"In the next 2 videos,"},{"Start":"15:59.390 ","End":"16:04.980","Text":"you\u0027ll apply what you\u0027ve learned in a real programming language. See you then."}],"ID":26345},{"Watched":false,"Name":"Introduction to BlueJ IDE","Duration":"10m 1s","ChapterTopicVideoID":25529,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.910","Text":"Welcome everybody to this video where I\u0027m going"},{"Start":"00:02.910 ","End":"00:05.745","Text":"to introduce you to the BlueJ environment."},{"Start":"00:05.745 ","End":"00:12.225","Text":"BlueJ is a free program that you can download from the following URL, bluej.org."},{"Start":"00:12.225 ","End":"00:16.840","Text":"It\u0027s used in universities all over the world to teach beginner programmers."},{"Start":"00:16.840 ","End":"00:20.375","Text":"It\u0027s designed specifically for beginners."},{"Start":"00:20.375 ","End":"00:23.540","Text":"First things first is to get to this URL,"},{"Start":"00:23.540 ","End":"00:26.150","Text":"and then when this homepage opens,"},{"Start":"00:26.150 ","End":"00:27.695","Text":"if you scroll down,"},{"Start":"00:27.695 ","End":"00:30.215","Text":"you will see this area for downloads."},{"Start":"00:30.215 ","End":"00:34.650","Text":"Choose the relevant operating system that will suit you."},{"Start":"00:34.650 ","End":"00:38.360","Text":"The BlueJ install will download and"},{"Start":"00:38.360 ","End":"00:41.640","Text":"with it will be something called the Java Development Kit."},{"Start":"00:41.640 ","End":"00:44.210","Text":"The Java Development Kit, or JDK,"},{"Start":"00:44.210 ","End":"00:50.555","Text":"is a set of files which you will need in order to develop Java programs."},{"Start":"00:50.555 ","End":"00:52.800","Text":"You don\u0027t need it to run programs."},{"Start":"00:52.800 ","End":"00:55.835","Text":"You need something called the Java runtime environment for that."},{"Start":"00:55.835 ","End":"00:59.310","Text":"But you will need it to compile programs."},{"Start":"00:59.310 ","End":"01:02.730","Text":"It will come bundled with BlueJ or it should do."},{"Start":"01:02.730 ","End":"01:05.420","Text":"You don\u0027t have to worry about that too much."},{"Start":"01:05.420 ","End":"01:10.085","Text":"Once you have it installed and run it for the first time,"},{"Start":"01:10.085 ","End":"01:14.135","Text":"you will come across the following environment."},{"Start":"01:14.135 ","End":"01:18.440","Text":"Just to give you a quick overview of the program"},{"Start":"01:18.440 ","End":"01:22.010","Text":"that I\u0027ve seen has a standard menu across the top here,"},{"Start":"01:22.010 ","End":"01:24.200","Text":"and the first thing we\u0027re going to need to do in order to be able to"},{"Start":"01:24.200 ","End":"01:26.630","Text":"do anything is to create a new project."},{"Start":"01:26.630 ","End":"01:30.985","Text":"If you go ahead and create a project by clicking on New Project,"},{"Start":"01:30.985 ","End":"01:33.000","Text":"giving it a name."},{"Start":"01:33.000 ","End":"01:41.120","Text":"We\u0027re going to complete some exercises on variables first."},{"Start":"01:41.120 ","End":"01:47.395","Text":"Let\u0027s call it exercises variable and create that for us."},{"Start":"01:47.395 ","End":"01:49.175","Text":"Just go full screen."},{"Start":"01:49.175 ","End":"01:52.475","Text":"You will now see that the display has changed slightly."},{"Start":"01:52.475 ","End":"01:55.580","Text":"You\u0027ve got a little icon representing a piece of paper here."},{"Start":"01:55.580 ","End":"01:57.620","Text":"This is just created for you in every project"},{"Start":"01:57.620 ","End":"02:00.920","Text":"to allow you to create some project documentation,"},{"Start":"02:00.920 ","End":"02:04.790","Text":"just a Read Me file basically which you can edit and add things to,"},{"Start":"02:04.790 ","End":"02:06.379","Text":"to describe your project."},{"Start":"02:06.379 ","End":"02:09.245","Text":"But the most significant thing that\u0027s happened is"},{"Start":"02:09.245 ","End":"02:12.770","Text":"there\u0027s a box that\u0027s appeared over here on the right-hand side."},{"Start":"02:12.770 ","End":"02:17.885","Text":"Now, this is a really important area that we\u0027ll be using initially called the code pad."},{"Start":"02:17.885 ","End":"02:19.760","Text":"The code pad, if it doesn\u0027t appear,"},{"Start":"02:19.760 ","End":"02:20.780","Text":"first of all for you,"},{"Start":"02:20.780 ","End":"02:24.930","Text":"you might need to activate by just going up to the View menu"},{"Start":"02:24.930 ","End":"02:31.080","Text":"here and just making sure that Show Code Pad has a tick mark next to it."},{"Start":"02:31.080 ","End":"02:33.540","Text":"In this case, obviously, it does and it appears."},{"Start":"02:33.540 ","End":"02:37.760","Text":"What we can do with the code pad is we can actually type lines of Java"},{"Start":"02:37.760 ","End":"02:42.290","Text":"in here directly and immediately get a response."},{"Start":"02:42.290 ","End":"02:46.840","Text":"Without creating a file and typing all the commands in there and compiling it,"},{"Start":"02:46.840 ","End":"02:51.530","Text":"we can try things out interactively in this environment here,"},{"Start":"02:51.530 ","End":"02:57.540","Text":"which makes learning a little bit more interesting and interactive."},{"Start":"02:57.540 ","End":"03:00.590","Text":"For example, if I wanted to create a variable,"},{"Start":"03:00.590 ","End":"03:03.770","Text":"I can go ahead and type in a command that"},{"Start":"03:03.770 ","End":"03:09.710","Text":"would declare the variable and store a value in it."},{"Start":"03:09.710 ","End":"03:12.245","Text":"Pull lines in Java end with a semicolon."},{"Start":"03:12.245 ","End":"03:14.635","Text":"I\u0027m going to end it with a semicolon."},{"Start":"03:14.635 ","End":"03:19.290","Text":"It appears to have done nothing but rest assured it has actually done something,"},{"Start":"03:19.290 ","End":"03:21.560","Text":"it\u0027s created that variable which is an integer,"},{"Start":"03:21.560 ","End":"03:24.530","Text":"and it currently contains the value 1234."},{"Start":"03:24.530 ","End":"03:26.480","Text":"If I want to see the value of the variable,"},{"Start":"03:26.480 ","End":"03:29.000","Text":"I can just type in the name of the variable."},{"Start":"03:29.000 ","End":"03:31.325","Text":"No, I don\u0027t need a semicolon here."},{"Start":"03:31.325 ","End":"03:36.365","Text":"I can simply just type the name of the variable and it responds with the value."},{"Start":"03:36.365 ","End":"03:39.590","Text":"This area here is both showing me the commands that I\u0027ve"},{"Start":"03:39.590 ","End":"03:42.920","Text":"typed in and then the responses that I get back,"},{"Start":"03:42.920 ","End":"03:47.375","Text":"and current values of variables here are displayed in green."},{"Start":"03:47.375 ","End":"03:49.475","Text":"Now I\u0027ve declared my variable."},{"Start":"03:49.475 ","End":"03:51.530","Text":"I don\u0027t need to put the data type again,"},{"Start":"03:51.530 ","End":"03:54.200","Text":"but if I want to specify another value,"},{"Start":"03:54.200 ","End":"03:56.240","Text":"I want to assign a different value to it."},{"Start":"03:56.240 ","End":"03:57.620","Text":"I can go ahead and do that."},{"Start":"03:57.620 ","End":"04:00.290","Text":"Once again, I won\u0027t press the semicolon."},{"Start":"04:00.290 ","End":"04:05.480","Text":"I see immediately the value is changed and displayed back to me."},{"Start":"04:05.480 ","End":"04:07.910","Text":"If by the way, you want to just repeat the previous command,"},{"Start":"04:07.910 ","End":"04:09.890","Text":"you can just use the up arrow key,"},{"Start":"04:09.890 ","End":"04:11.960","Text":"and that will bring up the previous command."},{"Start":"04:11.960 ","End":"04:14.390","Text":"You can edit it or you can do whatever you like with it."},{"Start":"04:14.390 ","End":"04:17.435","Text":"Let\u0027s just see what happens if I do put a semicolon on the end."},{"Start":"04:17.435 ","End":"04:20.190","Text":"Let\u0027s have a different value in here now."},{"Start":"04:20.190 ","End":"04:22.555","Text":"Let\u0027s go back to 1234,"},{"Start":"04:22.555 ","End":"04:24.035","Text":"I put a semicolon."},{"Start":"04:24.035 ","End":"04:28.805","Text":"You\u0027ll see that there is no response because I\u0027ve entered a complete valid line of Java,"},{"Start":"04:28.805 ","End":"04:31.580","Text":"the interaction side of it, it\u0027s not applying."},{"Start":"04:31.580 ","End":"04:35.690","Text":"It doesn\u0027t immediately show me the value that\u0027s stored in myVar as it did"},{"Start":"04:35.690 ","End":"04:40.670","Text":"previously when I left off the semicolon."},{"Start":"04:40.670 ","End":"04:44.240","Text":"If I want to see now the value of myVar again,"},{"Start":"04:44.240 ","End":"04:47.375","Text":"you should see that it\u0027s changed to 1234,"},{"Start":"04:47.375 ","End":"04:49.787","Text":"even though it didn\u0027t show me the value,"},{"Start":"04:49.787 ","End":"04:51.710","Text":"so that\u0027s the code pad."},{"Start":"04:51.710 ","End":"05:01.095","Text":"It\u0027s a very useful way of interacting with the system and trying out commands basically."},{"Start":"05:01.095 ","End":"05:05.335","Text":"The first exercises you\u0027ll complete will make use of the code pad."},{"Start":"05:05.335 ","End":"05:10.070","Text":"Now just to give you a brief overview of some of the other windows here."},{"Start":"05:10.070 ","End":"05:12.365","Text":"On the left-hand side,"},{"Start":"05:12.365 ","End":"05:15.710","Text":"this panel here is called the object workbench."},{"Start":"05:15.710 ","End":"05:18.290","Text":"Java is an object-oriented language."},{"Start":"05:18.290 ","End":"05:22.310","Text":"So everything is based on things called classes,"},{"Start":"05:22.310 ","End":"05:27.920","Text":"and classes are used to make objects and we\u0027ll do more of that later in the course."},{"Start":"05:27.920 ","End":"05:34.565","Text":"But for now, just be aware that anything that we write needs to be inside a class."},{"Start":"05:34.565 ","End":"05:36.575","Text":"I\u0027m going to write a Java program."},{"Start":"05:36.575 ","End":"05:38.555","Text":"If we\u0027re going to create some code,"},{"Start":"05:38.555 ","End":"05:40.280","Text":"we\u0027d have to go up to the top here,"},{"Start":"05:40.280 ","End":"05:42.535","Text":"click on New Class,"},{"Start":"05:42.535 ","End":"05:43.800","Text":"give it a name."},{"Start":"05:43.800 ","End":"05:46.220","Text":"It should, by convention,"},{"Start":"05:46.220 ","End":"05:50.585","Text":"always name classes with a capital letter at the first letter."},{"Start":"05:50.585 ","End":"05:53.630","Text":"It\u0027s called capital camel case."},{"Start":"05:53.630 ","End":"05:58.770","Text":"I\u0027m just going to call it MyApp and then click on Okay."},{"Start":"05:58.770 ","End":"06:05.340","Text":"What you\u0027ll see is a little rectangular appears in orangey-yellow color."},{"Start":"06:05.340 ","End":"06:08.020","Text":"Its got these diagonal lines across it."},{"Start":"06:08.020 ","End":"06:11.120","Text":"What that means is the program hasn\u0027t yet been compiled."},{"Start":"06:11.120 ","End":"06:13.595","Text":"If I click on this button over here, Compile,"},{"Start":"06:13.595 ","End":"06:18.815","Text":"you\u0027ll notice those diagonal lines have gone away and that\u0027s now compiled."},{"Start":"06:18.815 ","End":"06:23.030","Text":"Now I haven\u0027t actually written any code and BlueJ will create"},{"Start":"06:23.030 ","End":"06:27.845","Text":"some sample code for you for every new class that you create with a particular structure."},{"Start":"06:27.845 ","End":"06:30.410","Text":"If you want to see that code and you want to edit that code,"},{"Start":"06:30.410 ","End":"06:37.040","Text":"you just double-click on the class itself and up comes an editor window."},{"Start":"06:37.040 ","End":"06:38.780","Text":"In this editor window,"},{"Start":"06:38.780 ","End":"06:45.395","Text":"you can now change the source code to whatever it is that you want."},{"Start":"06:45.395 ","End":"06:50.225","Text":"As I said, BlueJ already creates some sample code for you."},{"Start":"06:50.225 ","End":"06:59.170","Text":"What I\u0027m going to do is I\u0027m going to actually remove everything from inside the class,"},{"Start":"06:59.170 ","End":"07:02.240","Text":"except for this first line here,"},{"Start":"07:02.240 ","End":"07:03.870","Text":"which defines the class,"},{"Start":"07:03.870 ","End":"07:05.720","Text":"and this pair of brackets here,"},{"Start":"07:05.720 ","End":"07:07.310","Text":"braces we call them."},{"Start":"07:07.310 ","End":"07:10.309","Text":"Actually, programmers tend to call them curly brackets."},{"Start":"07:10.309 ","End":"07:12.050","Text":"Within those curly brackets,"},{"Start":"07:12.050 ","End":"07:14.405","Text":"I can type some code."},{"Start":"07:14.405 ","End":"07:18.380","Text":"We\u0027ll get into it in a bit more detail in the next video."},{"Start":"07:18.380 ","End":"07:22.235","Text":"But for now, I\u0027m just going to create a variable."},{"Start":"07:22.235 ","End":"07:25.460","Text":"Again, I\u0027m going to create an integer variable."},{"Start":"07:25.460 ","End":"07:27.575","Text":"I\u0027m going to call it myNum."},{"Start":"07:27.575 ","End":"07:31.890","Text":"I\u0027m going to give it an initial value by assigning it a value,"},{"Start":"07:31.890 ","End":"07:34.065","Text":"and I\u0027ll make that 1234."},{"Start":"07:34.065 ","End":"07:37.760","Text":"You\u0027ll notice that I\u0027ve got diagonal lines again in the background"},{"Start":"07:37.760 ","End":"07:41.535","Text":"here on this icon and that other view,"},{"Start":"07:41.535 ","End":"07:44.745","Text":"and they\u0027ll go away if I click on the Compile button."},{"Start":"07:44.745 ","End":"07:47.580","Text":"Now I can close this window."},{"Start":"07:47.580 ","End":"07:49.530","Text":"To run the program,"},{"Start":"07:49.530 ","End":"07:53.590","Text":"what I can do is I can make what\u0027s called an object from this class,"},{"Start":"07:53.590 ","End":"07:57.550","Text":"and by right-clicking on it and saying new MyApp,"},{"Start":"07:57.550 ","End":"07:59.140","Text":"MyApp being the name of the class."},{"Start":"07:59.140 ","End":"08:01.030","Text":"If I click on it,"},{"Start":"08:01.030 ","End":"08:04.510","Text":"it\u0027s asking me to give a name to"},{"Start":"08:04.510 ","End":"08:10.330","Text":"this instance just so I can identify this particular instance of it."},{"Start":"08:10.330 ","End":"08:12.710","Text":"I\u0027ll click on Okay now."},{"Start":"08:12.710 ","End":"08:16.225","Text":"There we go. We\u0027ve created what\u0027s called an object,"},{"Start":"08:16.225 ","End":"08:17.815","Text":"and it\u0027s in red."},{"Start":"08:17.815 ","End":"08:20.785","Text":"This area is called the object workbench."},{"Start":"08:20.785 ","End":"08:22.390","Text":"It\u0027s unique to BlueJ,"},{"Start":"08:22.390 ","End":"08:26.570","Text":"which allows you to create objects and interact with them."},{"Start":"08:26.570 ","End":"08:30.380","Text":"For the moment, we won\u0027t be getting too much into object-oriented programming."},{"Start":"08:30.380 ","End":"08:33.635","Text":"We\u0027re just going to learn the real basics."},{"Start":"08:33.635 ","End":"08:38.225","Text":"But I\u0027m going to use the terms class and object from time to time."},{"Start":"08:38.225 ","End":"08:43.355","Text":"All you need to know for the moment is an object is an instance of a class."},{"Start":"08:43.355 ","End":"08:46.250","Text":"If I double-click on this here,"},{"Start":"08:46.250 ","End":"08:49.940","Text":"I should be able to see the inside of the code."},{"Start":"08:49.940 ","End":"08:55.385","Text":"All it\u0027s showing me is that we\u0027ve got a variable called myNum,"},{"Start":"08:55.385 ","End":"08:57.050","Text":"which is an integer,"},{"Start":"08:57.050 ","End":"09:00.875","Text":"and it\u0027s been given the value 1234."},{"Start":"09:00.875 ","End":"09:03.820","Text":"Because there\u0027s no other code in here for me to run,"},{"Start":"09:03.820 ","End":"09:05.720","Text":"that\u0027s literally all I can do."},{"Start":"09:05.720 ","End":"09:08.465","Text":"I can\u0027t actually run any other lines of code."},{"Start":"09:08.465 ","End":"09:11.570","Text":"I\u0027ve simply created a variable and store the value in it."},{"Start":"09:11.570 ","End":"09:15.710","Text":"But it gives you the idea of the different areas and what they\u0027re"},{"Start":"09:15.710 ","End":"09:20.030","Text":"responsible for within the BlueJ environment,"},{"Start":"09:20.030 ","End":"09:21.860","Text":"so that\u0027s it for now."},{"Start":"09:21.860 ","End":"09:27.290","Text":"We\u0027ve just had a look at the basic displays within the BlueJ ID,"},{"Start":"09:27.290 ","End":"09:31.490","Text":"given the class and files here at the top,"},{"Start":"09:31.490 ","End":"09:33.020","Text":"the code pad here,"},{"Start":"09:33.020 ","End":"09:36.125","Text":"and the object workbench here where we can create"},{"Start":"09:36.125 ","End":"09:39.210","Text":"objects and we can run code, and obviously,"},{"Start":"09:39.210 ","End":"09:43.235","Text":"the main menus at the top here where we create our project"},{"Start":"09:43.235 ","End":"09:48.635","Text":"and load it should we need to if we open another project at some point."},{"Start":"09:48.635 ","End":"09:51.560","Text":"That\u0027s it for this video."},{"Start":"09:51.560 ","End":"09:54.740","Text":"In the next one, we\u0027ll look at how to create a structure for"},{"Start":"09:54.740 ","End":"09:59.705","Text":"a simple program and how to output to the display."},{"Start":"09:59.705 ","End":"10:02.190","Text":"I\u0027ll see you then."}],"ID":26346},{"Watched":false,"Name":"Program structure in Java","Duration":"10m 56s","ChapterTopicVideoID":26015,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.490","Text":"Hi everybody, welcome back."},{"Start":"00:02.490 ","End":"00:03.900","Text":"In the previous video,"},{"Start":"00:03.900 ","End":"00:06.570","Text":"we created a new project and interacted with"},{"Start":"00:06.570 ","End":"00:11.115","Text":"a BlueJ environment by typing code into the code pad down here,"},{"Start":"00:11.115 ","End":"00:16.710","Text":"and creating 1 line program which we compiled and inspected using the object workbench,"},{"Start":"00:16.710 ","End":"00:19.215","Text":"which is usually found here."},{"Start":"00:19.215 ","End":"00:21.150","Text":"We\u0027re now going to look at the structure of"},{"Start":"00:21.150 ","End":"00:24.705","Text":"a simple Java program that creates more than a single variable."},{"Start":"00:24.705 ","End":"00:28.360","Text":"Let\u0027s start by creating a new project."},{"Start":"00:28.790 ","End":"00:31.890","Text":"As we said before,"},{"Start":"00:31.890 ","End":"00:36.405","Text":"all code in Java must be contained in something called a class."},{"Start":"00:36.405 ","End":"00:39.330","Text":"We have to click on New Class up here."},{"Start":"00:39.330 ","End":"00:46.830","Text":"I\u0027m just going to call my class myvariables and apps comes,"},{"Start":"00:46.830 ","End":"00:48.764","Text":"the icon for the class."},{"Start":"00:48.764 ","End":"00:51.075","Text":"If I now double-click on this,"},{"Start":"00:51.075 ","End":"00:58.245","Text":"what I\u0027ll see is the editor view,"},{"Start":"00:58.245 ","End":"01:05.165","Text":"and the editor shows me some default code that BlueJ has helpfully put in for me,"},{"Start":"01:05.165 ","End":"01:07.790","Text":"but I\u0027m going to remove it all just to make it easier for you"},{"Start":"01:07.790 ","End":"01:11.540","Text":"to see the structure of the class itself."},{"Start":"01:11.540 ","End":"01:13.370","Text":"I\u0027ll take out everything except for"},{"Start":"01:13.370 ","End":"01:17.510","Text":"the first 2 lines and that last closing bracket there."},{"Start":"01:17.510 ","End":"01:19.700","Text":"If I press Enter a few times,"},{"Start":"01:19.700 ","End":"01:21.320","Text":"I\u0027ve got a bit of space to write my code,"},{"Start":"01:21.320 ","End":"01:22.900","Text":"and every time I press Enter,"},{"Start":"01:22.900 ","End":"01:24.585","Text":"it adds a new line in."},{"Start":"01:24.585 ","End":"01:26.780","Text":"If I want to indent the code,"},{"Start":"01:26.780 ","End":"01:29.150","Text":"I just press the Tab key, like I\u0027ve done there."},{"Start":"01:29.150 ","End":"01:31.325","Text":"Sometimes it will do it automatically for you,"},{"Start":"01:31.325 ","End":"01:33.365","Text":"on the end of the previous line."},{"Start":"01:33.365 ","End":"01:36.785","Text":"The variables I want to create first,"},{"Start":"01:36.785 ","End":"01:38.600","Text":"go on the first few lines."},{"Start":"01:38.600 ","End":"01:41.540","Text":"I\u0027m just going to create a couple of integer variables."},{"Start":"01:41.540 ","End":"01:44.690","Text":"I\u0027m going to call them num1 and num2."},{"Start":"01:44.690 ","End":"01:47.300","Text":"I\u0027ll give num1 the value 10,"},{"Start":"01:47.300 ","End":"01:51.860","Text":"and I\u0027ll give num2 the value 20."},{"Start":"01:51.860 ","End":"01:55.370","Text":"I\u0027ve got my variables now and that\u0027s no different than what we had before,"},{"Start":"01:55.370 ","End":"02:00.050","Text":"but I want to create some code now that is not just declaring variables."},{"Start":"02:00.050 ","End":"02:03.620","Text":"To do that, I have to create something called a method."},{"Start":"02:03.620 ","End":"02:06.470","Text":"It\u0027s a separate block in which the lines"},{"Start":"02:06.470 ","End":"02:10.380","Text":"of code that are going to be executed are stored."},{"Start":"02:10.570 ","End":"02:14.705","Text":"First thing I have to do is put a keyword void for now."},{"Start":"02:14.705 ","End":"02:18.320","Text":"Void basically tells the compiler that"},{"Start":"02:18.320 ","End":"02:21.800","Text":"nothing is going to be returned by this piece of code."},{"Start":"02:21.800 ","End":"02:25.100","Text":"Then I just give my piece of code a name,"},{"Start":"02:25.100 ","End":"02:26.510","Text":"I\u0027m going to call it test."},{"Start":"02:26.510 ","End":"02:30.590","Text":"I need a pair of empty round brackets here for the moment."},{"Start":"02:30.590 ","End":"02:31.940","Text":"I\u0027m going to do that,"},{"Start":"02:31.940 ","End":"02:34.520","Text":"and then everything that\u0027s going to go inside"},{"Start":"02:34.520 ","End":"02:41.660","Text":"my block is between this opening curly bracket here and the closing 1 there."},{"Start":"02:41.660 ","End":"02:44.840","Text":"You\u0027ll notice when you click on a bracket,"},{"Start":"02:44.840 ","End":"02:46.775","Text":"if it\u0027s been matched up to something,"},{"Start":"02:46.775 ","End":"02:48.785","Text":"it will be in gray."},{"Start":"02:48.785 ","End":"02:51.005","Text":"You can see those 2 are in gray,"},{"Start":"02:51.005 ","End":"02:54.065","Text":"and this pair is in gray, as well here."},{"Start":"02:54.065 ","End":"02:56.780","Text":"I click on that one, it shows these 2 in gray,"},{"Start":"02:56.780 ","End":"03:01.115","Text":"so you\u0027ve got matching of opening and closing brackets there."},{"Start":"03:01.115 ","End":"03:05.150","Text":"Back to my method here called test,"},{"Start":"03:05.150 ","End":"03:10.775","Text":"I\u0027m going to now put a line of code that will just output something to the screen."},{"Start":"03:10.775 ","End":"03:13.580","Text":"That looks like this,"},{"Start":"03:13.580 ","End":"03:20.315","Text":"it\u0027s called a print line method and it belongs to a package called system.out."},{"Start":"03:20.315 ","End":"03:25.745","Text":"I have to put system.out.printline in order to run this or it won\u0027t work or get an error."},{"Start":"03:25.745 ","End":"03:28.280","Text":"Traditionally, what we usually say in"},{"Start":"03:28.280 ","End":"03:31.145","Text":"a new program for the first time"},{"Start":"03:31.145 ","End":"03:34.355","Text":"when we\u0027ve written something in a new language or new environment,"},{"Start":"03:34.355 ","End":"03:36.350","Text":"just to test things out is Hello world."},{"Start":"03:36.350 ","End":"03:38.120","Text":"Let\u0027s go ahead and do that."},{"Start":"03:38.120 ","End":"03:42.950","Text":"Now, I can compile my program and I\u0027ll close the editor, there\u0027s no errors."},{"Start":"03:42.950 ","End":"03:48.125","Text":"You\u0027ll see that this icon has now changed so that it\u0027s not hashed anymore."},{"Start":"03:48.125 ","End":"03:53.045","Text":"Now, another thing I need to do is to make sure I can see the output from my code,"},{"Start":"03:53.045 ","End":"03:54.965","Text":"in something called the terminal,"},{"Start":"03:54.965 ","End":"03:58.575","Text":"so I\u0027ll turn the terminal on by saying View Terminal,"},{"Start":"03:58.575 ","End":"04:00.000","Text":"and up it comes."},{"Start":"04:00.000 ","End":"04:02.375","Text":"It\u0027s also useful to have that open"},{"Start":"04:02.375 ","End":"04:05.435","Text":"while I\u0027ve got the development of the environment on the left-hand side."},{"Start":"04:05.435 ","End":"04:07.490","Text":"I\u0027m just going to minimize this."},{"Start":"04:07.490 ","End":"04:10.115","Text":"I\u0027ve got the 2 windows side by side."},{"Start":"04:10.115 ","End":"04:14.600","Text":"Now I\u0027m going to run my code by creating an object as we did previously,"},{"Start":"04:14.600 ","End":"04:17.170","Text":"objects are created from classes,"},{"Start":"04:17.170 ","End":"04:19.430","Text":"and I just click on this menu item here."},{"Start":"04:19.430 ","End":"04:22.955","Text":"I accept the name that it\u0027s given the object by default."},{"Start":"04:22.955 ","End":"04:25.190","Text":"Here\u0027s our object, and now I can interact with"},{"Start":"04:25.190 ","End":"04:27.950","Text":"the object by inspecting the variables inside it."},{"Start":"04:27.950 ","End":"04:28.970","Text":"If I double-click on it,"},{"Start":"04:28.970 ","End":"04:30.575","Text":"it will show me those variables."},{"Start":"04:30.575 ","End":"04:33.499","Text":"We can see we\u0027ve got 2 variables, num1 and num2."},{"Start":"04:33.499 ","End":"04:36.530","Text":"That\u0027s really no further than where we were before,"},{"Start":"04:36.530 ","End":"04:42.710","Text":"but now what we will see if I right-click is a method called test also appears."},{"Start":"04:42.710 ","End":"04:44.495","Text":"If I left-click on this,"},{"Start":"04:44.495 ","End":"04:47.270","Text":"it will run the code inside test and"},{"Start":"04:47.270 ","End":"04:50.255","Text":"the output will be shown in the terminal window on the right."},{"Start":"04:50.255 ","End":"04:52.250","Text":"If I do that, there we go,"},{"Start":"04:52.250 ","End":"04:53.527","Text":"we see the words,"},{"Start":"04:53.527 ","End":"04:56.285","Text":"Hello World popup at the top of the screen."},{"Start":"04:56.285 ","End":"04:57.770","Text":"If I want to clear that message,"},{"Start":"04:57.770 ","End":"05:01.235","Text":"I can click on Clear or if I\u0027ve got this button,"},{"Start":"05:01.235 ","End":"05:03.980","Text":"this menu item here ticked,"},{"Start":"05:03.980 ","End":"05:05.720","Text":"Clear screen at method call,"},{"Start":"05:05.720 ","End":"05:07.880","Text":"then every time I call a method,"},{"Start":"05:07.880 ","End":"05:09.650","Text":"it will clear the screen."},{"Start":"05:09.650 ","End":"05:11.660","Text":"If I untick that, we\u0027ll see the effect,"},{"Start":"05:11.660 ","End":"05:13.235","Text":"I\u0027ll call test again,"},{"Start":"05:13.235 ","End":"05:18.365","Text":"and it will just display Hello world under the previous 1."},{"Start":"05:18.365 ","End":"05:22.385","Text":"But if I turn back on Clear screen at method call,"},{"Start":"05:22.385 ","End":"05:24.905","Text":"every time I call a method, any method,"},{"Start":"05:24.905 ","End":"05:28.790","Text":"it will clear whatever was in the terminal window before."},{"Start":"05:28.790 ","End":"05:33.530","Text":"There you go, and you see it\u0027s just 1 test message being output."},{"Start":"05:33.530 ","End":"05:36.980","Text":"There again, it\u0027s clear the screen and display the same message again."},{"Start":"05:36.980 ","End":"05:41.690","Text":"Let\u0027s go back to our program now and let\u0027s change the contents of 1 of these variables."},{"Start":"05:41.690 ","End":"05:44.060","Text":"We won\u0027t do it by changing up here."},{"Start":"05:44.060 ","End":"05:48.065","Text":"We\u0027ll actually do it inside this method."},{"Start":"05:48.065 ","End":"05:51.665","Text":"We\u0027ll also print out the value of the variable."},{"Start":"05:51.665 ","End":"05:58.805","Text":"If I change the inside of the brackets here and put the name of the variable, no,"},{"Start":"05:58.805 ","End":"06:00.860","Text":"I don\u0027t need any speech marks around this"},{"Start":"06:00.860 ","End":"06:04.402","Text":"because I don\u0027t want to print the literal characters,"},{"Start":"06:04.402 ","End":"06:10.460","Text":"num1, I want to print the contents of the variable that I\u0027ve called num1."},{"Start":"06:10.460 ","End":"06:12.080","Text":"If I run this,"},{"Start":"06:12.080 ","End":"06:15.980","Text":"I should see 10 appear on the screen because"},{"Start":"06:15.980 ","End":"06:20.555","Text":"num1 contains 10 and I\u0027ve never changed it anywhere in this program."},{"Start":"06:20.555 ","End":"06:22.790","Text":"Let\u0027s see if that indeed happens."},{"Start":"06:22.790 ","End":"06:27.305","Text":"Let\u0027s create a class again and run the method."},{"Start":"06:27.305 ","End":"06:31.295","Text":"There we see 10 appears on the screen as we expected."},{"Start":"06:31.295 ","End":"06:33.695","Text":"I\u0027ll go back into my code now."},{"Start":"06:33.695 ","End":"06:36.710","Text":"Let\u0027s do this more than once."},{"Start":"06:36.710 ","End":"06:41.540","Text":"I\u0027m going to copy this line and I\u0027m going to paste it below in-between,"},{"Start":"06:41.540 ","End":"06:42.770","Text":"press Enter in front of it."},{"Start":"06:42.770 ","End":"06:44.450","Text":"I\u0027ve got a gap of a line."},{"Start":"06:44.450 ","End":"06:50.400","Text":"I\u0027m going to change the value of num1 to 30,"},{"Start":"06:50.400 ","End":"06:52.485","Text":"so I\u0027m printing num1 here,"},{"Start":"06:52.485 ","End":"06:55.055","Text":"I\u0027m changing the value of num1 to 30,"},{"Start":"06:55.055 ","End":"06:56.450","Text":"and then I\u0027m printing it again."},{"Start":"06:56.450 ","End":"06:58.955","Text":"Let\u0027s see what the effect of that is."},{"Start":"06:58.955 ","End":"07:00.920","Text":"Create a new object,"},{"Start":"07:00.920 ","End":"07:03.695","Text":"run a test method from that object."},{"Start":"07:03.695 ","End":"07:06.335","Text":"There we go, we see 10 appears first,"},{"Start":"07:06.335 ","End":"07:08.765","Text":"and 30 appears afterwards,"},{"Start":"07:08.765 ","End":"07:10.370","Text":"just as we\u0027d expect."},{"Start":"07:10.370 ","End":"07:13.655","Text":"If obviously, I want to print the contents of this other variable,"},{"Start":"07:13.655 ","End":"07:17.535","Text":"I can change the name of the variable here."},{"Start":"07:17.535 ","End":"07:22.625","Text":"I would expect it to then print 10 first because that\u0027s what\u0027s in there,"},{"Start":"07:22.625 ","End":"07:25.070","Text":"and then 20 afterwards."},{"Start":"07:25.070 ","End":"07:28.415","Text":"Even though I\u0027ve changed num1 to 30,"},{"Start":"07:28.415 ","End":"07:34.230","Text":"it won\u0027t print that because I\u0027m specifying num2 here other than num1."},{"Start":"07:34.230 ","End":"07:39.320","Text":"What if you want to print some text and the contents of the variable on the same line?"},{"Start":"07:39.320 ","End":"07:44.959","Text":"You can do that by putting whatever the text is in speech marks."},{"Start":"07:44.959 ","End":"07:48.770","Text":"I\u0027ll say contents of num1 and a colon."},{"Start":"07:48.770 ","End":"07:52.610","Text":"Close the speech marks and then you put a plus afterwards."},{"Start":"07:52.610 ","End":"07:59.260","Text":"What this is doing is just joining this string to the contents of the num1 variable."},{"Start":"07:59.260 ","End":"08:03.785","Text":"This will also be a string because everything for print line is going to be a string."},{"Start":"08:03.785 ","End":"08:07.640","Text":"It actually does a job of converting this to a string for us when we print"},{"Start":"08:07.640 ","End":"08:11.390","Text":"it out and joining it to the end of this message here."},{"Start":"08:11.390 ","End":"08:15.259","Text":"I\u0027ll do the same for contents of num2."},{"Start":"08:15.259 ","End":"08:17.220","Text":"Just take this line out here,"},{"Start":"08:17.220 ","End":"08:19.145","Text":"because that seem unnecessary."},{"Start":"08:19.145 ","End":"08:23.090","Text":"Compile again, close the editor window,"},{"Start":"08:23.090 ","End":"08:27.950","Text":"New object, run the test method from that object, and there we go."},{"Start":"08:27.950 ","End":"08:30.110","Text":"Now, it prints a little message and the value of"},{"Start":"08:30.110 ","End":"08:34.700","Text":"num1 and another message and the value of num2."},{"Start":"08:34.700 ","End":"08:36.410","Text":"That\u0027s pretty much it."},{"Start":"08:36.410 ","End":"08:38.359","Text":"You can do this to your heart\u0027s content,"},{"Start":"08:38.359 ","End":"08:40.160","Text":"declare variables out here,"},{"Start":"08:40.160 ","End":"08:43.160","Text":"and then print their contents out and"},{"Start":"08:43.160 ","End":"08:47.345","Text":"change the values of the variables in here as you wish."},{"Start":"08:47.345 ","End":"08:50.240","Text":"I\u0027ll try and do a slightly different assignment now."},{"Start":"08:50.240 ","End":"08:52.849","Text":"Let\u0027s try a hex assignment."},{"Start":"08:52.849 ","End":"08:55.850","Text":"You remember that if you want to assign a hex value,"},{"Start":"08:55.850 ","End":"08:58.265","Text":"you put 0x in front of it."},{"Start":"08:58.265 ","End":"09:01.960","Text":"I\u0027m going to say 0xabcd,"},{"Start":"09:01.960 ","End":"09:03.420","Text":"and see if that works,"},{"Start":"09:03.420 ","End":"09:06.095","Text":"and num1 should print something very strange now,"},{"Start":"09:06.095 ","End":"09:09.245","Text":"abcd or it\u0027s decimal equivalent."},{"Start":"09:09.245 ","End":"09:10.835","Text":"I\u0027ll take that second line out."},{"Start":"09:10.835 ","End":"09:12.905","Text":"Just to prove that this works."},{"Start":"09:12.905 ","End":"09:16.125","Text":"Let\u0027s just have a quick look at that, and there we go,"},{"Start":"09:16.125 ","End":"09:25.200","Text":"43,981 is the decimal version of abcd in hexadecimal."},{"Start":"09:25.200 ","End":"09:27.020","Text":"Have a little play around with that."},{"Start":"09:27.020 ","End":"09:28.820","Text":"If you do make a mistake,"},{"Start":"09:28.820 ","End":"09:32.095","Text":"for example, a very common 1 is missing a semicolon,"},{"Start":"09:32.095 ","End":"09:34.070","Text":"when you try and compile,"},{"Start":"09:34.070 ","End":"09:37.775","Text":"you\u0027ll see that little red mark appears in the margin there."},{"Start":"09:37.775 ","End":"09:40.025","Text":"It says, errors found in class here."},{"Start":"09:40.025 ","End":"09:42.905","Text":"If you click on line where that red appears,"},{"Start":"09:42.905 ","End":"09:46.040","Text":"it tries to help you identify the error."},{"Start":"09:46.040 ","End":"09:47.360","Text":"This one is a simple 1,"},{"Start":"09:47.360 ","End":"09:52.160","Text":"the semicolon\u0027s missing, but some more strange ones."},{"Start":"09:52.160 ","End":"09:57.750","Text":"For example, you forget to capitalize the capital S here at the beginning of System,"},{"Start":"09:57.750 ","End":"09:59.940","Text":"and Java is a case-sensitive language,"},{"Start":"09:59.940 ","End":"10:01.610","Text":"so it will complain about that."},{"Start":"10:01.610 ","End":"10:05.015","Text":"Now, we\u0027ll give a slightly more obscure error."},{"Start":"10:05.015 ","End":"10:07.030","Text":"Let\u0027s see what that is."},{"Start":"10:07.030 ","End":"10:10.670","Text":"Let\u0027s compile it, and it\u0027s saying the package system does not"},{"Start":"10:10.670 ","End":"10:14.270","Text":"exist because System with a capital S exists,"},{"Start":"10:14.270 ","End":"10:17.565","Text":"but system with a lowercase s does not,"},{"Start":"10:17.565 ","End":"10:19.445","Text":"and that\u0027s what it\u0027s complaining about."},{"Start":"10:19.445 ","End":"10:21.730","Text":"If I restore that to a capital S,"},{"Start":"10:21.730 ","End":"10:26.120","Text":"it stops complaining and I don\u0027t get anymore syntax errors."},{"Start":"10:26.120 ","End":"10:28.450","Text":"Don\u0027t worry about making mistakes at this point,"},{"Start":"10:28.450 ","End":"10:30.385","Text":"that\u0027s an important part of learning."},{"Start":"10:30.385 ","End":"10:32.080","Text":"You\u0027re going to forget semi-colons,"},{"Start":"10:32.080 ","End":"10:34.850","Text":"you\u0027ll forget to close a bracket that you previously opened,"},{"Start":"10:34.850 ","End":"10:37.115","Text":"you\u0027ll forget to capitalize the letter and so on,"},{"Start":"10:37.115 ","End":"10:38.945","Text":"is absolutely fine right now."},{"Start":"10:38.945 ","End":"10:40.430","Text":"That\u0027s what we\u0027d expect,"},{"Start":"10:40.430 ","End":"10:43.310","Text":"and the key is to just manage your frustrations and"},{"Start":"10:43.310 ","End":"10:46.430","Text":"just work through the errors patiently 1 by 1."},{"Start":"10:46.430 ","End":"10:49.945","Text":"That\u0027s it for now, you should be ready to complete the exercises."},{"Start":"10:49.945 ","End":"10:54.440","Text":"Have a go, and refer back to this video and the previous ones if you need to."},{"Start":"10:54.440 ","End":"10:57.090","Text":"Thanks very much and see you soon."}],"ID":26823},{"Watched":false,"Name":"Exercise 1","Duration":"7m 22s","ChapterTopicVideoID":26436,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:06.555","Text":"Hello everyone, and welcome to this first exercise on variables and primitive datatypes."},{"Start":"00:06.555 ","End":"00:11.340","Text":"Here we\u0027ve been asked to create a new project firstly and then open the Code Pad in"},{"Start":"00:11.340 ","End":"00:15.900","Text":"BlueJ and then to do the following 4 steps in the Code Pad."},{"Start":"00:15.900 ","End":"00:18.450","Text":"Part A, we\u0027re asked to create a new variable"},{"Start":"00:18.450 ","End":"00:21.450","Text":"called found that only stores Boolean values."},{"Start":"00:21.450 ","End":"00:25.935","Text":"In Part B we\u0027re then asked to store a Boolean value in found."},{"Start":"00:25.935 ","End":"00:29.280","Text":"In Part C to check that that Boolean value is stored"},{"Start":"00:29.280 ","End":"00:33.015","Text":"correctly by typing in found followed by the Enter key."},{"Start":"00:33.015 ","End":"00:37.110","Text":"Then in Part D, we are asked to try to store an integer value into"},{"Start":"00:37.110 ","End":"00:42.325","Text":"found to see what would happen and then explain what we find."},{"Start":"00:42.325 ","End":"00:45.919","Text":"Hello everybody, welcome to this first question"},{"Start":"00:45.919 ","End":"00:49.420","Text":"in the topic on variables and primitive datatypes."},{"Start":"00:49.420 ","End":"00:53.645","Text":"In the question we\u0027ve been asked to create a new project and open the Code Pad in BlueJ."},{"Start":"00:53.645 ","End":"00:55.875","Text":"I\u0027ve got BlueJ up right now."},{"Start":"00:55.875 ","End":"00:58.160","Text":"What you\u0027ll see is that Code Pad is here in the corner,"},{"Start":"00:58.160 ","End":"01:00.920","Text":"but it\u0027s inactive and that\u0027s because you can\u0027t"},{"Start":"01:00.920 ","End":"01:04.935","Text":"use the Code Pad unless you\u0027ve got an active project."},{"Start":"01:04.935 ","End":"01:08.915","Text":"If we just go ahead and create a new project and give it a name,"},{"Start":"01:08.915 ","End":"01:15.620","Text":"I\u0027m just going to call mine Topic 3 and what you\u0027ll then see is that the Code Pad now"},{"Start":"01:15.620 ","End":"01:18.575","Text":"becomes active in the bottom and it\u0027s probably useful to make"},{"Start":"01:18.575 ","End":"01:22.775","Text":"the space available to the Code Pad bigger just by resizing,"},{"Start":"01:22.775 ","End":"01:24.740","Text":"dragging on these bars here."},{"Start":"01:24.740 ","End":"01:26.300","Text":"I\u0027ve got a bit more space to see"},{"Start":"01:26.300 ","End":"01:29.900","Text":"the response from any commands that I type into the Code Pad."},{"Start":"01:29.900 ","End":"01:35.728","Text":"Down here at the bottom is where I\u0027m seeing the prompt to type in my commands,"},{"Start":"01:35.728 ","End":"01:39.080","Text":"and the first thing I need to do is create a new variable."},{"Start":"01:39.080 ","End":"01:43.940","Text":"I\u0027ve been told to call it found and it should store only Boolean values."},{"Start":"01:43.940 ","End":"01:46.940","Text":"When you\u0027re creating a variable in Java,"},{"Start":"01:46.940 ","End":"01:49.385","Text":"you have to state the datatype."},{"Start":"01:49.385 ","End":"01:53.720","Text":"If this is a variable that only contains Boolean values,"},{"Start":"01:53.720 ","End":"01:57.080","Text":"obviously the datatype is going to be Boolean."},{"Start":"01:57.080 ","End":"01:59.045","Text":"That\u0027s how we got to start the line."},{"Start":"01:59.045 ","End":"02:01.879","Text":"Then we give the name of the variable."},{"Start":"02:01.879 ","End":"02:04.640","Text":"In this case, we\u0027ve been told to call it found,"},{"Start":"02:04.640 ","End":"02:06.290","Text":"and I can end it there."},{"Start":"02:06.290 ","End":"02:10.715","Text":"Now, if I was to write this in a Java program and not in the Code Pad,"},{"Start":"02:10.715 ","End":"02:13.970","Text":"I would be obliged to put a semicolon at the end of the line,"},{"Start":"02:13.970 ","End":"02:17.675","Text":"because lines in Java end with a semicolon."},{"Start":"02:17.675 ","End":"02:19.100","Text":"I\u0027ve gone ahead and done that."},{"Start":"02:19.100 ","End":"02:20.495","Text":"If I hadn\u0027t done that,"},{"Start":"02:20.495 ","End":"02:24.495","Text":"it would still have created it in the Code Pad and it would immediately"},{"Start":"02:24.495 ","End":"02:29.255","Text":"have echoed back to me the value stored in found."},{"Start":"02:29.255 ","End":"02:32.855","Text":"When you don\u0027t give a value to a variable when you create it,"},{"Start":"02:32.855 ","End":"02:36.530","Text":"it will get a default value and that\u0027s what this message"},{"Start":"02:36.530 ","End":"02:40.985","Text":"here is telling us that it\u0027s happened, is automatically initialized."},{"Start":"02:40.985 ","End":"02:44.660","Text":"We can see what the value is stored in that variable."},{"Start":"02:44.660 ","End":"02:46.295","Text":"I haven\u0027t stored anything into it,"},{"Start":"02:46.295 ","End":"02:49.310","Text":"but I can actually see it by just typing"},{"Start":"02:49.310 ","End":"02:52.770","Text":"the name of the variable and it will tell me what was stored in there."},{"Start":"02:52.770 ","End":"02:54.890","Text":"It seems that by default,"},{"Start":"02:54.890 ","End":"02:59.465","Text":"Boolean variables have the value false stored into them."},{"Start":"02:59.465 ","End":"03:03.800","Text":"Let\u0027s store a different value in found."},{"Start":"03:03.800 ","End":"03:07.370","Text":"Because that\u0027s what Part B of this question asks us to do."},{"Start":"03:07.370 ","End":"03:10.705","Text":"To do that, we just give the name of the variable which is"},{"Start":"03:10.705 ","End":"03:16.240","Text":"found and follow it with an equals and give it a different value."},{"Start":"03:16.240 ","End":"03:17.740","Text":"Let\u0027s give it true."},{"Start":"03:17.740 ","End":"03:22.560","Text":"Now we know that that\u0027s the other value that you can give to variables."},{"Start":"03:22.560 ","End":"03:24.030","Text":"I\u0027ve mistyped that."},{"Start":"03:24.030 ","End":"03:27.460","Text":"If you ever do that, up-arrow will bring"},{"Start":"03:27.460 ","End":"03:32.440","Text":"the previously typed thing in to the little white box at the bottom there,"},{"Start":"03:32.440 ","End":"03:35.605","Text":"and you can just delete anything that you want to change."},{"Start":"03:35.605 ","End":"03:39.490","Text":"I\u0027ve inadvertently typed the hash key when I was pressing \"Enter\" there."},{"Start":"03:39.490 ","End":"03:45.130","Text":"Press \"Enter\" again, and I\u0027ve now found that it\u0027s stored the variable value"},{"Start":"03:45.130 ","End":"03:50.260","Text":"true into the variable found and it\u0027s echoed that back to me as I said before,"},{"Start":"03:50.260 ","End":"03:53.880","Text":"because I didn\u0027t put a semicolon on the end of this line."},{"Start":"03:53.880 ","End":"03:58.445","Text":"If I had, it would still store true,"},{"Start":"03:58.445 ","End":"04:01.100","Text":"but it just wouldn\u0027t echo back a value to me."},{"Start":"04:01.100 ","End":"04:05.420","Text":"You\u0027ll see that the command is being repeated here in black but"},{"Start":"04:05.420 ","End":"04:07.610","Text":"it\u0027s not giving me a value in green as it"},{"Start":"04:07.610 ","End":"04:10.160","Text":"did previously because I\u0027ve missed out the semicolon."},{"Start":"04:10.160 ","End":"04:13.010","Text":"That\u0027s the first 2 bits done."},{"Start":"04:13.010 ","End":"04:18.065","Text":"I\u0027ve just created a variable and I had to state the datatype first."},{"Start":"04:18.065 ","End":"04:22.955","Text":"Then I\u0027ve had to change the value in the variable to true."},{"Start":"04:22.955 ","End":"04:28.805","Text":"The last part here, it asked me to store an integer value in found to see what happens."},{"Start":"04:28.805 ","End":"04:30.995","Text":"Let\u0027s go ahead and do that."},{"Start":"04:30.995 ","End":"04:35.570","Text":"If I put found equals and then just make up any old integer value of 1,"},{"Start":"04:35.570 ","End":"04:38.825","Text":"2, 3, 4 say, and press \"Enter\"."},{"Start":"04:38.825 ","End":"04:41.135","Text":"I get an error message."},{"Start":"04:41.135 ","End":"04:43.370","Text":"It says incompatible types,"},{"Start":"04:43.370 ","End":"04:46.235","Text":"int cannot be converted to Boolean."},{"Start":"04:46.235 ","End":"04:52.070","Text":"Error messages in programming languages can be quite cryptic sometimes."},{"Start":"04:52.070 ","End":"04:54.560","Text":"This one\u0027s not too bad as it goes."},{"Start":"04:54.560 ","End":"04:59.360","Text":"You can work out why it\u0027s complaining and what it\u0027s complaining about."},{"Start":"04:59.360 ","End":"05:04.625","Text":"It\u0027s saying something about int and Boolean types."},{"Start":"05:04.625 ","End":"05:11.225","Text":"As we\u0027ve tried to assign an integer value to a Boolean variable,"},{"Start":"05:11.225 ","End":"05:13.580","Text":"it\u0027s not allowing it."},{"Start":"05:13.580 ","End":"05:16.765","Text":"This really is the only point of this exercise,"},{"Start":"05:16.765 ","End":"05:20.140","Text":"which is to demonstrate the datatypes"},{"Start":"05:20.140 ","End":"05:24.369","Text":"constrain what you can do with a particular variable."},{"Start":"05:24.369 ","End":"05:28.525","Text":"In this case, we\u0027ve set the datatype to Boolean."},{"Start":"05:28.525 ","End":"05:31.195","Text":"It can only store Booleans."},{"Start":"05:31.195 ","End":"05:33.670","Text":"If I try to store another datatype,"},{"Start":"05:33.670 ","End":"05:37.750","Text":"it will give me an error message at compile time."},{"Start":"05:37.750 ","End":"05:40.810","Text":"I\u0027m not compiling my program because there is no program,"},{"Start":"05:40.810 ","End":"05:47.695","Text":"I\u0027m just messing around in the Code Pad just to experiment with the features in Java."},{"Start":"05:47.695 ","End":"05:52.000","Text":"But it would give me an error message if I put this in a line in a program because I\u0027m"},{"Start":"05:52.000 ","End":"05:56.685","Text":"trying to put an integer value into a Boolean variable and clearly,"},{"Start":"05:56.685 ","End":"05:58.220","Text":"it doesn\u0027t want me to do that."},{"Start":"05:58.220 ","End":"06:00.530","Text":"Interestingly, there are some languages that"},{"Start":"06:00.530 ","End":"06:03.260","Text":"don\u0027t really complain about this sort of stuff."},{"Start":"06:03.260 ","End":"06:05.585","Text":"They have what\u0027s called dynamic typing."},{"Start":"06:05.585 ","End":"06:11.795","Text":"That means really any variable can be any datatype and it can switch between them."},{"Start":"06:11.795 ","End":"06:15.260","Text":"But Java is a statically typed language."},{"Start":"06:15.260 ","End":"06:18.080","Text":"That means once you create a type,"},{"Start":"06:18.080 ","End":"06:23.105","Text":"you\u0027re always going to be in that datatype and you can\u0027t change its datatype."},{"Start":"06:23.105 ","End":"06:25.640","Text":"If you want a different variable to store an integer,"},{"Start":"06:25.640 ","End":"06:28.850","Text":"you\u0027re going to have to declare a different variable with a different datatype."},{"Start":"06:28.850 ","End":"06:33.770","Text":"That\u0027s why we get this particular error and that\u0027s the explanation for why this"},{"Start":"06:33.770 ","End":"06:39.200","Text":"happens that you\u0027ve been asked to give in Part D. That was a nice,"},{"Start":"06:39.200 ","End":"06:42.725","Text":"gentle introduction to these exercises."},{"Start":"06:42.725 ","End":"06:45.080","Text":"Nice and simple. We\u0027ve created a project"},{"Start":"06:45.080 ","End":"06:47.780","Text":"which we had to in order to open up the Code Pad,"},{"Start":"06:47.780 ","End":"06:49.355","Text":"resize the window,"},{"Start":"06:49.355 ","End":"06:52.250","Text":"then we created a variable and stored a value,"},{"Start":"06:52.250 ","End":"06:56.120","Text":"changed the value, revealed what value is in there by just typing the name."},{"Start":"06:56.120 ","End":"07:03.500","Text":"Then we tried to put in a value that wasn\u0027t allowed and we saw why it wasn\u0027t allowed."},{"Start":"07:03.500 ","End":"07:09.470","Text":"In that, we\u0027re really now discovering this idea of datatypes being a constraint,"},{"Start":"07:09.470 ","End":"07:12.050","Text":"as well as something that will determine how"},{"Start":"07:12.050 ","End":"07:14.855","Text":"much memory space something\u0027s going to take up."},{"Start":"07:14.855 ","End":"07:16.610","Text":"That\u0027s it for this one. I\u0027ll see you in"},{"Start":"07:16.610 ","End":"07:18.140","Text":"the next one where we\u0027ll do something a little bit"},{"Start":"07:18.140 ","End":"07:22.380","Text":"more involved with integers. See you then."}],"ID":27342},{"Watched":false,"Name":"Exercise 2","Duration":"11m 26s","ChapterTopicVideoID":26435,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.430","Text":"Hi, everybody. Welcome back."},{"Start":"00:02.430 ","End":"00:05.700","Text":"In this exercise, we\u0027re going to continue looking at variables"},{"Start":"00:05.700 ","End":"00:09.390","Text":"and primitive data types using the code pad as we did it before."},{"Start":"00:09.390 ","End":"00:12.930","Text":"This exercise is about storing values using decimal,"},{"Start":"00:12.930 ","End":"00:15.555","Text":"hexadecimal, and binary literals."},{"Start":"00:15.555 ","End":"00:19.605","Text":"In parts a to c we\u0027ll be dealing with decimals."},{"Start":"00:19.605 ","End":"00:24.000","Text":"We\u0027ve been asked in part a to create a new variable to store 7 bits"},{"Start":"00:24.000 ","End":"00:29.430","Text":"signed integer value using the byte data type and to choose a sensible name."},{"Start":"00:29.430 ","End":"00:33.990","Text":"Then we\u0027re asked to store the value 10 decimal into that variable."},{"Start":"00:33.990 ","End":"00:35.530","Text":"Then finally in part c,"},{"Start":"00:35.530 ","End":"00:38.210","Text":"to check that the value is stored correctly by"},{"Start":"00:38.210 ","End":"00:41.675","Text":"typing the variable name and followed by the enter key."},{"Start":"00:41.675 ","End":"00:45.875","Text":"Then in part d too we\u0027re dealing with a hex questions."},{"Start":"00:45.875 ","End":"00:49.940","Text":"The prefix 0x is used to store a hexadecimal value into"},{"Start":"00:49.940 ","End":"00:54.505","Text":"the variable when you use that rather than the decimal representation."},{"Start":"00:54.505 ","End":"00:59.645","Text":"We want you to store the hexadecimal value 5F into the variable we created"},{"Start":"00:59.645 ","End":"01:06.110","Text":"earlier in part d. Then in part e to check that that value is 95 decimal,"},{"Start":"01:06.110 ","End":"01:09.245","Text":"and that it has been successfully stored into the variable."},{"Start":"01:09.245 ","End":"01:10.910","Text":"Then finally in part f,"},{"Start":"01:10.910 ","End":"01:17.375","Text":"to try to put the hexadecimal value AF into the variable and explain what happens."},{"Start":"01:17.375 ","End":"01:21.845","Text":"Part g and h then are where we use binary literals."},{"Start":"01:21.845 ","End":"01:26.315","Text":"The prefix 0b can be used to store a binary value into a variable."},{"Start":"01:26.315 ","End":"01:33.000","Text":"We want to store that binary variable given here into the variable we created in part a,"},{"Start":"01:33.000 ","End":"01:39.020","Text":"and then confirm that the value decimal 92 has been stored."},{"Start":"01:39.020 ","End":"01:41.660","Text":"Then the last part is to store"},{"Start":"01:41.660 ","End":"01:46.505","Text":"this new binary value into the variable and explain what happens."},{"Start":"01:46.505 ","End":"01:51.500","Text":"You can stay open in the same project as you had before in the same code pad window."},{"Start":"01:51.500 ","End":"01:54.433","Text":"I\u0027ve closed down Bluej and reopened it,"},{"Start":"01:54.433 ","End":"01:57.155","Text":"and that\u0027s why this area is empty here."},{"Start":"01:57.155 ","End":"02:01.730","Text":"But you may well have some output here and that\u0027s absolutely fine."},{"Start":"02:01.730 ","End":"02:04.560","Text":"You can continue on as normal."},{"Start":"02:04.560 ","End":"02:06.680","Text":"Let\u0027s look at the first part, part a."},{"Start":"02:06.680 ","End":"02:09.620","Text":"It\u0027s asking us to create a new variable to store a 7 bits signed"},{"Start":"02:09.620 ","End":"02:13.410","Text":"integer using the byte datatype and a sensible name."},{"Start":"02:13.410 ","End":"02:16.520","Text":"This time we have been told what name to give it."},{"Start":"02:16.520 ","End":"02:21.265","Text":"Naming as we know, is a very important part of making our code readable,"},{"Start":"02:21.265 ","End":"02:24.320","Text":"understandable, choosing sensible names to store things."},{"Start":"02:24.320 ","End":"02:27.185","Text":"We don\u0027t know what this variable is going to store,"},{"Start":"02:27.185 ","End":"02:30.440","Text":"but we do know that it\u0027s a data type of byte."},{"Start":"02:30.440 ","End":"02:34.910","Text":"Sometimes the convention that programmers use is to put"},{"Start":"02:34.910 ","End":"02:40.310","Text":"a prefix ahead of the variable name to indicate what the datatype is,"},{"Start":"02:40.310 ","End":"02:42.395","Text":"so maybe I\u0027ll try that."},{"Start":"02:42.395 ","End":"02:45.500","Text":"The datatype itself comes first as before,"},{"Start":"02:45.500 ","End":"02:50.090","Text":"I need to type the name of the data type and it\u0027s a byte data type, all lowercase."},{"Start":"02:50.090 ","End":"02:51.665","Text":"Then I\u0027m going to give my name,"},{"Start":"02:51.665 ","End":"02:53.990","Text":"and I\u0027m going to put a lowercase b in front of it"},{"Start":"02:53.990 ","End":"02:56.450","Text":"just to indicate that it\u0027s a byte datatype."},{"Start":"02:56.450 ","End":"02:59.690","Text":"You don\u0027t have to do this, I\u0027m just using that convention."},{"Start":"02:59.690 ","End":"03:03.620","Text":"Then I\u0027m going to give it a name and I\u0027m going to call it,"},{"Start":"03:03.620 ","End":"03:05.165","Text":"let\u0027s say a mask."},{"Start":"03:05.165 ","End":"03:08.195","Text":"A mask is something that is used quite often."},{"Start":"03:08.195 ","End":"03:14.270","Text":"Mask out areas of a network and binary values are often used to do that."},{"Start":"03:14.270 ","End":"03:19.085","Text":"I could imagine a scenario where we\u0027d have a variable called mask."},{"Start":"03:19.085 ","End":"03:23.285","Text":"I\u0027m going to put b in front of it just to indicate that this data type is"},{"Start":"03:23.285 ","End":"03:28.535","Text":"a byte because some programs will use that convention. There we go."},{"Start":"03:28.535 ","End":"03:30.800","Text":"I\u0027m going to put a semicolon as you know,"},{"Start":"03:30.800 ","End":"03:34.520","Text":"what that does is it puts the variable into memory,"},{"Start":"03:34.520 ","End":"03:37.670","Text":"but it doesn\u0027t reflect back to me what the value of the variable is."},{"Start":"03:37.670 ","End":"03:40.250","Text":"If I had left off the semicolon, it would\u0027ve done."},{"Start":"03:40.250 ","End":"03:41.555","Text":"But if I want the value,"},{"Start":"03:41.555 ","End":"03:43.880","Text":"I can just type the name of the variable,"},{"Start":"03:43.880 ","End":"03:45.725","Text":"and it will give the value."},{"Start":"03:45.725 ","End":"03:49.040","Text":"We\u0027ll see that it has actually created a byte data type,"},{"Start":"03:49.040 ","End":"03:52.160","Text":"the name of my variable is bMask,"},{"Start":"03:52.160 ","End":"03:54.255","Text":"and it currently has a value of 0."},{"Start":"03:54.255 ","End":"03:59.315","Text":"It seems that when you don\u0027t give it an initial value to a byte data type,"},{"Start":"03:59.315 ","End":"04:03.620","Text":"in Java, it assigns a default value of 0."},{"Start":"04:03.620 ","End":"04:07.745","Text":"We\u0027ve been asked in part b to store the value 10 into the variable."},{"Start":"04:07.745 ","End":"04:10.655","Text":"That\u0027s 10 decimal. Sounds straightforward enough."},{"Start":"04:10.655 ","End":"04:12.320","Text":"We\u0027ve seen this before,"},{"Start":"04:12.320 ","End":"04:14.520","Text":"and we\u0027ll do that,"},{"Start":"04:14.520 ","End":"04:16.760","Text":"and there doesn\u0027t seem to be any complaints."},{"Start":"04:16.760 ","End":"04:20.390","Text":"I left the semicolon off the end there."},{"Start":"04:20.390 ","End":"04:23.120","Text":"It\u0027s reflected back the value to me immediately,"},{"Start":"04:23.120 ","End":"04:24.490","Text":"but if I had typed it,"},{"Start":"04:24.490 ","End":"04:26.540","Text":"it would\u0027ve done the same thing."},{"Start":"04:26.540 ","End":"04:31.310","Text":"Now we\u0027re on to part d. We\u0027re going to check that we can use"},{"Start":"04:31.310 ","End":"04:38.720","Text":"a prefix of 0x to store a hexadecimal value into the variable rather than a decimal."},{"Start":"04:38.720 ","End":"04:43.420","Text":"We tend to work with decimal values because humans are used to decimal."},{"Start":"04:43.420 ","End":"04:49.760","Text":"But it might be that it\u0027s more convenient to state a value in hexadecimal."},{"Start":"04:49.760 ","End":"04:53.060","Text":"Let\u0027s see if we are able to do that."},{"Start":"04:53.060 ","End":"04:56.630","Text":"We\u0027re going to put the name of the variable, the equal sign,"},{"Start":"04:56.630 ","End":"04:59.900","Text":"and then we give our value in hexadecimal,"},{"Start":"04:59.900 ","End":"05:03.890","Text":"but we have to prefix it with 0 and x."},{"Start":"05:03.890 ","End":"05:05.720","Text":"That tells it\u0027s hexadecimal,"},{"Start":"05:05.720 ","End":"05:07.145","Text":"there\u0027s no spaces,"},{"Start":"05:07.145 ","End":"05:11.074","Text":"and I\u0027ll put the value 5f in as I was requested,"},{"Start":"05:11.074 ","End":"05:14.055","Text":"and it gets stored."},{"Start":"05:14.055 ","End":"05:19.830","Text":"It does give me the value of 95 decimal because 5"},{"Start":"05:19.830 ","End":"05:25.875","Text":"times 16 plus 15 is 95,"},{"Start":"05:25.875 ","End":"05:27.904","Text":"so that\u0027s what we\u0027d expect."},{"Start":"05:27.904 ","End":"05:29.540","Text":"That looks good."},{"Start":"05:29.540 ","End":"05:37.050","Text":"Let\u0027s just check what would have happened if we didn\u0027t put the 0x in front of the number."},{"Start":"05:37.050 ","End":"05:39.610","Text":"We got an error."},{"Start":"05:40.430 ","End":"05:42.650","Text":"In this case, interestingly,"},{"Start":"05:42.650 ","End":"05:46.640","Text":"it thinks that it\u0027s a float because of the f. Very interesting."},{"Start":"05:46.640 ","End":"05:50.960","Text":"I\u0027m going to try another value of hexadecimal."},{"Start":"05:50.960 ","End":"05:57.525","Text":"Let\u0027s say a 5c that\u0027s slightly different since an error expected."},{"Start":"05:57.525 ","End":"05:59.190","Text":"Semicolon. It still give me,"},{"Start":"05:59.190 ","End":"06:00.810","Text":"it\u0027s a very strange error."},{"Start":"06:00.810 ","End":"06:03.110","Text":"Some quite odd things can happen."},{"Start":"06:03.110 ","End":"06:05.510","Text":"I can\u0027t even explain why that has happened."},{"Start":"06:05.510 ","End":"06:09.575","Text":"It thinks I haven\u0027t terminated the line properly."},{"Start":"06:09.575 ","End":"06:16.325","Text":"Clearly, I think the c is something different than a hexadecimal character."},{"Start":"06:16.325 ","End":"06:22.790","Text":"That\u0027s what happens if we don\u0027t put 0x in front of the hexadecimal value."},{"Start":"06:22.790 ","End":"06:25.820","Text":"You see that? Now it\u0027s absolutely happy with it."},{"Start":"06:25.820 ","End":"06:29.840","Text":"This illustrates you can get some quite strange error messages"},{"Start":"06:29.840 ","End":"06:32.030","Text":"that don\u0027t really give you a clue as"},{"Start":"06:32.030 ","End":"06:34.310","Text":"to what\u0027s gone wrong and that is what"},{"Start":"06:34.310 ","End":"06:38.285","Text":"a beginner programmer will often find a real frustration."},{"Start":"06:38.285 ","End":"06:42.080","Text":"We\u0027ve done now part d and we\u0027ve checked it,"},{"Start":"06:42.080 ","End":"06:44.210","Text":"which is part e. If I just"},{"Start":"06:44.210 ","End":"06:47.090","Text":"restore the original value that I was supposed to put in there,"},{"Start":"06:47.090 ","End":"06:50.135","Text":"5f, there it is."},{"Start":"06:50.135 ","End":"06:53.090","Text":"It\u0027s a value 95. Now it\u0027s asked me in"},{"Start":"06:53.090 ","End":"06:58.925","Text":"part f to try and put the hexadecimal value af into the variable."},{"Start":"06:58.925 ","End":"07:03.080","Text":"Let\u0027s try that. I get an error message."},{"Start":"07:03.080 ","End":"07:06.810","Text":"Cannot find symbol variable af."},{"Start":"07:06.810 ","End":"07:09.725","Text":"That\u0027s because I didn\u0027t put 0x in front of it."},{"Start":"07:09.725 ","End":"07:11.720","Text":"It thinks it\u0027s a variable name."},{"Start":"07:11.720 ","End":"07:15.365","Text":"The characters a and f form a variable name, which makes sense."},{"Start":"07:15.365 ","End":"07:17.585","Text":"Let\u0027s try and put Ox in front of it."},{"Start":"07:17.585 ","End":"07:24.200","Text":"Now another error and this one we might be able"},{"Start":"07:24.200 ","End":"07:31.160","Text":"to judge from the previous exercise is related to the problem we had previously."},{"Start":"07:31.160 ","End":"07:38.060","Text":"Incompatible types, possible lousy conversion from int to byte."},{"Start":"07:38.060 ","End":"07:41.435","Text":"Can we explain what\u0027s happening here?"},{"Start":"07:41.435 ","End":"07:45.110","Text":"Well, what is happening is"},{"Start":"07:45.110 ","End":"07:53.120","Text":"the number af is a larger number than can be stored in 7 bits."},{"Start":"07:53.120 ","End":"07:57.290","Text":"A you remember is 10 in hexadecimal."},{"Start":"07:57.290 ","End":"08:00.820","Text":"10 times 16 would be 160 plus 15,"},{"Start":"08:00.820 ","End":"08:07.235","Text":"which is f, 175 is a number that cannot be stored in 7 bits."},{"Start":"08:07.235 ","End":"08:11.995","Text":"The highest number you can store with 7 bits is 127,"},{"Start":"08:11.995 ","End":"08:18.020","Text":"so we can\u0027t store this number into bMask because it\u0027s basically too big."},{"Start":"08:18.020 ","End":"08:21.760","Text":"That\u0027s the error message that we\u0027ve been given."},{"Start":"08:21.760 ","End":"08:26.810","Text":"If we had stored an integer which is larger than a byte,"},{"Start":"08:26.810 ","End":"08:29.870","Text":"then it would have been absolutely fine."},{"Start":"08:29.870 ","End":"08:36.350","Text":"That is why we are seeing that error message and hope that makes sense just"},{"Start":"08:36.350 ","End":"08:42.230","Text":"to prove that we can get any value that\u0027s smaller than a 127 in here."},{"Start":"08:42.230 ","End":"08:44.405","Text":"We could try in decimal if we wanted to."},{"Start":"08:44.405 ","End":"08:46.480","Text":"Let\u0027s try 128."},{"Start":"08:46.480 ","End":"08:48.605","Text":"Again it gives me the same error."},{"Start":"08:48.605 ","End":"08:51.040","Text":"Let\u0027s put a 127 in there,"},{"Start":"08:51.040 ","End":"08:54.320","Text":"and it\u0027s absolutely happy with that."},{"Start":"08:54.320 ","End":"08:58.550","Text":"That\u0027s parts a to f done."},{"Start":"08:58.550 ","End":"09:01.220","Text":"Then we\u0027ve been told that you can actually put"},{"Start":"09:01.220 ","End":"09:05.210","Text":"binary values into byte variable or to any variable,"},{"Start":"09:05.210 ","End":"09:06.900","Text":"and it stores numbers,"},{"Start":"09:06.900 ","End":"09:08.270","Text":"so let\u0027s try that."},{"Start":"09:08.270 ","End":"09:12.810","Text":"Let\u0027s make bMask prefix sum equal to 0b."},{"Start":"09:12.810 ","End":"09:17.850","Text":"I\u0027ve been given a number here to store 01011100,"},{"Start":"09:19.040 ","End":"09:24.320","Text":"and it goes and I can confirm that 92 has been"},{"Start":"09:24.320 ","End":"09:29.880","Text":"stored in there because it\u0027s reflected back to me there in the code pad window."},{"Start":"09:30.320 ","End":"09:32.745","Text":"All good so far."},{"Start":"09:32.745 ","End":"09:35.085","Text":"Then let\u0027s just do the last part."},{"Start":"09:35.085 ","End":"09:42.315","Text":"The value 10000000 into the same variable."},{"Start":"09:42.315 ","End":"09:44.243","Text":"Let\u0027s give that a go,"},{"Start":"09:44.243 ","End":"09:47.220","Text":"0b and then 10000000."},{"Start":"09:47.600 ","End":"09:55.000","Text":"Again, I get the error message talking about loss aversion from int to byte."},{"Start":"09:55.000 ","End":"09:56.625","Text":"For the same reason,"},{"Start":"09:56.625 ","End":"09:59.005","Text":"as we saw before in part f,"},{"Start":"09:59.005 ","End":"10:02.750","Text":"I simply cannot store a number this big into a byte"},{"Start":"10:02.750 ","End":"10:06.580","Text":"because that is the binary value for a 128,"},{"Start":"10:06.580 ","End":"10:11.299","Text":"and we\u0027ve already proved that you can\u0027t store 128 into"},{"Start":"10:11.299 ","End":"10:17.230","Text":"the variable because we tried to do that here and it gave us an error message."},{"Start":"10:17.230 ","End":"10:24.365","Text":"There we go. We have been able to store various values into our byte datatype variable."},{"Start":"10:24.365 ","End":"10:29.555","Text":"We saw that you can\u0027t store values greater than a certain amount."},{"Start":"10:29.555 ","End":"10:34.055","Text":"Basically, 127 is the highest value you can put in."},{"Start":"10:34.055 ","End":"10:37.235","Text":"What we didn\u0027t do is store a negative value in."},{"Start":"10:37.235 ","End":"10:38.660","Text":"We can try that if we want."},{"Start":"10:38.660 ","End":"10:43.220","Text":"Let\u0027s put into bMask a value of minus 127,"},{"Start":"10:43.220 ","End":"10:44.530","Text":"see if it\u0027s happy with that."},{"Start":"10:44.530 ","End":"10:49.680","Text":"It is. This is what we mean by a signed data type."},{"Start":"10:49.680 ","End":"10:51.820","Text":"It\u0027s a signed integer, therefore,"},{"Start":"10:51.820 ","End":"10:54.050","Text":"we can have a positive or a negative number."},{"Start":"10:54.050 ","End":"10:56.990","Text":"In some languages, you can have unsigned integers,"},{"Start":"10:56.990 ","End":"11:01.910","Text":"which means you get to use the whole range of available bit values."},{"Start":"11:01.910 ","End":"11:05.824","Text":"But it will just be a positive number always."},{"Start":"11:05.824 ","End":"11:14.540","Text":"Java byte default is all variables are signed variables if they are to store numbers."},{"Start":"11:14.540 ","End":"11:17.985","Text":"That\u0027s it for this exercise,"},{"Start":"11:17.985 ","End":"11:22.355","Text":"we\u0027ll move on in the next one to slightly larger integers,"},{"Start":"11:22.355 ","End":"11:27.060","Text":"and I\u0027ll see you for that one soon. Take care."}],"ID":27343},{"Watched":false,"Name":"Exercise 3","Duration":"9m 18s","ChapterTopicVideoID":26439,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.140 ","End":"00:03.450","Text":"Hi, welcome back. In this exercise,"},{"Start":"00:03.450 ","End":"00:06.840","Text":"we\u0027ve been asked in the Code Pad once again to first of all"},{"Start":"00:06.840 ","End":"00:11.310","Text":"create a variable in Code Pad and to call it myInt,"},{"Start":"00:11.310 ","End":"00:13.110","Text":"and that should store an integer."},{"Start":"00:13.110 ","End":"00:16.560","Text":"In Part B, then we\u0027ve been asked to store into that variable"},{"Start":"00:16.560 ","End":"00:20.790","Text":"the maximum negative value that\u0027s possible."},{"Start":"00:20.790 ","End":"00:23.145","Text":"We\u0027ve been given a little hint here."},{"Start":"00:23.145 ","End":"00:26.745","Text":"In Part C, we\u0027re then being asked to type myInt,"},{"Start":"00:26.745 ","End":"00:29.010","Text":"the name of the variable, and to press \"Enter\" to check"},{"Start":"00:29.010 ","End":"00:31.875","Text":"that that intended value was stored."},{"Start":"00:31.875 ","End":"00:33.735","Text":"Then in Part D,"},{"Start":"00:33.735 ","End":"00:39.475","Text":"we\u0027re then asked to store the maximum positive value that was possible into myInt,"},{"Start":"00:39.475 ","End":"00:42.830","Text":"and then again, to check that that intended value was stored."},{"Start":"00:42.830 ","End":"00:44.750","Text":"In Part E,"},{"Start":"00:44.750 ","End":"00:48.170","Text":"we\u0027ve been asked to take the value that was stored,"},{"Start":"00:48.170 ","End":"00:50.210","Text":"the maximum positive value that was stored,"},{"Start":"00:50.210 ","End":"00:52.700","Text":"and to then type a following little fragment of"},{"Start":"00:52.700 ","End":"00:56.000","Text":"code which will add 1 to the contents of my variable."},{"Start":"00:56.000 ","End":"01:00.460","Text":"The fragment of code is myInt plus equals 1."},{"Start":"01:00.460 ","End":"01:04.820","Text":"Then finally, we\u0027ve been told that the results should be a negative number,"},{"Start":"01:04.820 ","End":"01:08.015","Text":"and to explain why that happens."},{"Start":"01:08.015 ","End":"01:13.175","Text":"It asked us initially to create another variable in Code Pad."},{"Start":"01:13.175 ","End":"01:15.685","Text":"This time, let\u0027s give it a name,"},{"Start":"01:15.685 ","End":"01:19.700","Text":"myInt, and we need to store an integer."},{"Start":"01:19.700 ","End":"01:22.760","Text":"Now, the first thing you might have been thinking here is,"},{"Start":"01:22.760 ","End":"01:27.470","Text":"well, I could have several different types of integer, and you\u0027re quite right."},{"Start":"01:27.470 ","End":"01:28.850","Text":"A bit after all,"},{"Start":"01:28.850 ","End":"01:30.410","Text":"is a type of integer,"},{"Start":"01:30.410 ","End":"01:33.995","Text":"meaning essentially a whole number with no fractional part,"},{"Start":"01:33.995 ","End":"01:36.424","Text":"but it\u0027s a particular size."},{"Start":"01:36.424 ","End":"01:38.900","Text":"If we have been just told an integer,"},{"Start":"01:38.900 ","End":"01:41.840","Text":"there is a datatype in Java called int,"},{"Start":"01:41.840 ","End":"01:43.688","Text":"which is an integer,"},{"Start":"01:43.688 ","End":"01:45.800","Text":"and it\u0027s actually 32 bits,"},{"Start":"01:45.800 ","End":"01:48.065","Text":"which it tells us in the next part of the question."},{"Start":"01:48.065 ","End":"01:50.555","Text":"But we don\u0027t type the full word, integer out,"},{"Start":"01:50.555 ","End":"01:53.645","Text":"it\u0027s just int on its own I-N-T."},{"Start":"01:53.645 ","End":"01:59.400","Text":"There is actually something called an integer in Java with a I,"},{"Start":"01:59.400 ","End":"02:03.380","Text":"but that\u0027s not something we\u0027re interested in at this point."},{"Start":"02:03.380 ","End":"02:07.250","Text":"We just want an int variable which will give us integer"},{"Start":"02:07.250 ","End":"02:12.855","Text":"datatype variable and I\u0027ve been given the name to use, which is myInt."},{"Start":"02:12.855 ","End":"02:15.110","Text":"There we go, create a variable."},{"Start":"02:15.110 ","End":"02:18.665","Text":"It goes ahead and does that for me."},{"Start":"02:18.665 ","End":"02:20.405","Text":"In Part B,"},{"Start":"02:20.405 ","End":"02:27.305","Text":"I\u0027ve now been asked to store the maximum negative value possible in an int."},{"Start":"02:27.305 ","End":"02:29.960","Text":"It does give me a hint here saying that"},{"Start":"02:29.960 ","End":"02:34.880","Text":"Java integer datatypes are signed and use 32 bits."},{"Start":"02:34.880 ","End":"02:37.115","Text":"There\u0027s a couple of ways I could do this."},{"Start":"02:37.115 ","End":"02:40.940","Text":"The easiest way is to use a calculator to work"},{"Start":"02:40.940 ","End":"02:46.400","Text":"out what the maximum negative number is that I can store in 32 bits."},{"Start":"02:46.400 ","End":"02:49.790","Text":"You\u0027ll recall that there is a formula for this,"},{"Start":"02:49.790 ","End":"02:59.505","Text":"2^n-1 will give us the largest negative value you can store in a variable."},{"Start":"02:59.505 ","End":"03:03.105","Text":"In this case, n will be 32,"},{"Start":"03:03.105 ","End":"03:06.040","Text":"n minus 1 is going to be 31,"},{"Start":"03:06.080 ","End":"03:13.535","Text":"2^31 gives us 2147483648."},{"Start":"03:13.535 ","End":"03:16.354","Text":"That\u0027s what I\u0027m going to need to store in my variable."},{"Start":"03:16.354 ","End":"03:24.000","Text":"Let\u0027s put that value in, 2147483648,"},{"Start":"03:24.430 ","End":"03:27.920","Text":"except I forgot it\u0027s supposed to be a negative value,"},{"Start":"03:27.920 ","End":"03:32.900","Text":"so I need to put p sign in front of it and if I don\u0027t put a semicolon in,"},{"Start":"03:32.900 ","End":"03:38.315","Text":"it will put the value in and it will reflect it back to me if it was successfully stored."},{"Start":"03:38.315 ","End":"03:41.300","Text":"It does, so that\u0027s great."},{"Start":"03:41.300 ","End":"03:46.390","Text":"I know I can store that very large number into an int datatype."},{"Start":"03:46.390 ","End":"03:48.550","Text":"My variable called myInt,"},{"Start":"03:48.550 ","End":"03:52.565","Text":"now has a very large negative number in it,"},{"Start":"03:52.565 ","End":"03:59.435","Text":"and that\u0027s the most negative number I can store in an int datatype."},{"Start":"03:59.435 ","End":"04:04.595","Text":"As I said, we saw the formula for this back in Topic 1,"},{"Start":"04:04.595 ","End":"04:07.940","Text":"for signed numbers and 2s complement,"},{"Start":"04:07.940 ","End":"04:10.910","Text":"2^n-1, gives us"},{"Start":"04:10.910 ","End":"04:13.910","Text":"the largest negative value I"},{"Start":"04:13.910 ","End":"04:17.210","Text":"can have given a particular number of bits, so that\u0027s great."},{"Start":"04:17.210 ","End":"04:20.390","Text":"That\u0027s Part A and B done,"},{"Start":"04:20.390 ","End":"04:23.000","Text":"and C as well because it\u0027s reflected back."},{"Start":"04:23.000 ","End":"04:27.275","Text":"But if you want, I can type it out and it will give me the value again."},{"Start":"04:27.275 ","End":"04:29.585","Text":"Now, in Part D,"},{"Start":"04:29.585 ","End":"04:36.180","Text":"it\u0027s asked me to store the maximum positive value in myInt and check that it was stored."},{"Start":"04:36.180 ","End":"04:39.725","Text":"Surely that\u0027s just the case of flipping a bit, isn\u0027t it?"},{"Start":"04:39.725 ","End":"04:42.450","Text":"Flipping the sign, I should say."},{"Start":"04:42.450 ","End":"04:45.765","Text":"However, what you\u0027ll find if you try that,"},{"Start":"04:45.765 ","End":"04:49.159","Text":"is it says integer number too large."},{"Start":"04:49.159 ","End":"04:56.840","Text":"The reason for this is that signed 2s complement numbers are actually not symmetrical."},{"Start":"04:56.840 ","End":"05:03.230","Text":"You can store slightly more negative values than you can positive values."},{"Start":"05:03.230 ","End":"05:04.940","Text":"The formula actually goes,"},{"Start":"05:04.940 ","End":"05:12.774","Text":"the range from negative to positive is 2^n-1 on the negative side,"},{"Start":"05:12.774 ","End":"05:16.610","Text":"but on the positive side it\u0027s 2^n-1,"},{"Start":"05:16.610 ","End":"05:20.480","Text":"and then we subtract 1 from that number."},{"Start":"05:20.480 ","End":"05:24.150","Text":"Actually, the largest positive number I can store,"},{"Start":"05:24.150 ","End":"05:27.725","Text":"is going to be what I just attempted to store in there,"},{"Start":"05:27.725 ","End":"05:30.720","Text":"but I\u0027m going to have to take 1 off it,"},{"Start":"05:30.720 ","End":"05:40.850","Text":"so 47483647 is the largest positive number"},{"Start":"05:40.850 ","End":"05:42.350","Text":"I can store into an int."},{"Start":"05:42.350 ","End":"05:44.705","Text":"Let\u0027s try that. Sure enough,"},{"Start":"05:44.705 ","End":"05:48.335","Text":"it\u0027s happy, and it\u0027s allowed me to store it,"},{"Start":"05:48.335 ","End":"05:54.420","Text":"so 242147483648 gave me an error,"},{"Start":"05:54.420 ","End":"05:57.529","Text":"the integer number is too large."},{"Start":"05:57.529 ","End":"05:59.570","Text":"But when I took 1 off it,"},{"Start":"05:59.570 ","End":"06:01.355","Text":"it did allow me to store that."},{"Start":"06:01.355 ","End":"06:06.725","Text":"As I said, the reason for that is the formula that we looked at in Topic 1,"},{"Start":"06:06.725 ","End":"06:12.035","Text":"which shows you the range of a 2s complement number,"},{"Start":"06:12.035 ","End":"06:15.185","Text":"and it\u0027s not symmetrical across 0,"},{"Start":"06:15.185 ","End":"06:19.825","Text":"and you can have slightly more negative numbers then positive numbers."},{"Start":"06:19.825 ","End":"06:21.715","Text":"That\u0027s great, that done."},{"Start":"06:21.715 ","End":"06:26.650","Text":"Now, in Part E it says with this maximum positive value stored,"},{"Start":"06:26.650 ","End":"06:30.670","Text":"type the following, which will add 1 to the contents of the variable."},{"Start":"06:30.670 ","End":"06:36.520","Text":"I\u0027m going to type exactly what we were asked to type in exactly the same order."},{"Start":"06:36.520 ","End":"06:39.250","Text":"Looks slightly strange, we haven\u0027t seen this before and we\u0027ll come"},{"Start":"06:39.250 ","End":"06:42.355","Text":"across the explanation for this in the next topic."},{"Start":"06:42.355 ","End":"06:49.068","Text":"But for now, we just want to see what the effect of this line will be on our variable."},{"Start":"06:49.068 ","End":"06:50.470","Text":"Off we go."},{"Start":"06:50.470 ","End":"06:56.130","Text":"Now, myInt has been reflected back to me and weirdly,"},{"Start":"06:56.130 ","End":"07:03.105","Text":"I\u0027ve added 1 to this positive number and what I\u0027ve got is a negative number,"},{"Start":"07:03.105 ","End":"07:07.030","Text":"and I\u0027m being asked to explain why that happens."},{"Start":"07:07.030 ","End":"07:14.905","Text":"Well, what happens when you try and increment a number that is already a maximum,"},{"Start":"07:14.905 ","End":"07:23.769","Text":"is it will wrap around to the largest negative value that\u0027s available in the datatype."},{"Start":"07:23.769 ","End":"07:29.305","Text":"When I added 1 onto 2147483647,"},{"Start":"07:29.305 ","End":"07:31.580","Text":"it made it overflow,"},{"Start":"07:31.580 ","End":"07:34.350","Text":"essentially the size of that variable,"},{"Start":"07:34.350 ","End":"07:39.199","Text":"and it went to the largest negative value that was possible."},{"Start":"07:39.199 ","End":"07:47.495","Text":"That\u0027s why I see minus 2147483648 stored."},{"Start":"07:47.495 ","End":"07:50.685","Text":"Very strange seeming results,"},{"Start":"07:50.685 ","End":"07:57.925","Text":"I\u0027m adding 1 to the largest possible number and I\u0027m getting the largest negative number."},{"Start":"07:57.925 ","End":"08:00.090","Text":"Very odd. If I kept on repeating that,"},{"Start":"08:00.090 ","End":"08:01.605","Text":"you could see what happens."},{"Start":"08:01.605 ","End":"08:03.150","Text":"That\u0027s working fine,"},{"Start":"08:03.150 ","End":"08:04.655","Text":"that makes sense, doesn\u0027t it?"},{"Start":"08:04.655 ","End":"08:10.055","Text":"The number is getting less negative as I keep adding 1 onto it."},{"Start":"08:10.055 ","End":"08:16.610","Text":"But when I had the large positive value and it was as big as it could possibly be,"},{"Start":"08:16.610 ","End":"08:19.085","Text":"when I tried to add 1 more,"},{"Start":"08:19.085 ","End":"08:21.360","Text":"it went to a negative value,"},{"Start":"08:21.360 ","End":"08:23.915","Text":"so this is something programmers need to be aware of."},{"Start":"08:23.915 ","End":"08:26.300","Text":"You can actually overflow the size of"},{"Start":"08:26.300 ","End":"08:30.350","Text":"a variable and you\u0027ll get some fairly strange things happening."},{"Start":"08:30.350 ","End":"08:32.765","Text":"Essentially, if once you go past"},{"Start":"08:32.765 ","End":"08:38.165","Text":"the highest positive number that can be stored in a certain size variable,"},{"Start":"08:38.165 ","End":"08:42.240","Text":"you will start going into the negative range and that will play"},{"Start":"08:42.240 ","End":"08:46.610","Text":"havoc with your calculations and your program in general."},{"Start":"08:46.610 ","End":"08:48.420","Text":"Just be aware of that issue,"},{"Start":"08:48.420 ","End":"08:53.060","Text":"that variables can only store data of a certain size,"},{"Start":"08:53.060 ","End":"08:57.335","Text":"and if you try and break that limit,"},{"Start":"08:57.335 ","End":"09:00.380","Text":"you\u0027re going to have some strange effects going on."},{"Start":"09:00.380 ","End":"09:04.785","Text":"That\u0027s really what this exercise was illustrating."},{"Start":"09:04.785 ","End":"09:08.770","Text":"That\u0027s us done for Question 3."},{"Start":"09:08.770 ","End":"09:10.600","Text":"I\u0027ll see you shortly,"},{"Start":"09:10.600 ","End":"09:18.180","Text":"and we\u0027ll move on to even bigger integers in the next question. See you then."}],"ID":27344},{"Watched":false,"Name":"Exercise 4","Duration":"8m 36s","ChapterTopicVideoID":26438,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.040","Text":"Hello, again. Welcome back to this next video where we\u0027ve been asked to continue on in"},{"Start":"00:05.040 ","End":"00:07.980","Text":"the code pad and to create a new variable called"},{"Start":"00:07.980 ","End":"00:11.595","Text":"myLong this time to store a long integer."},{"Start":"00:11.595 ","End":"00:16.657","Text":"Then in part b, we\u0027ve been asked to store into myLong the number 2,"},{"Start":"00:16.657 ","End":"00:18.725","Text":"147, 483,"},{"Start":"00:18.725 ","End":"00:21.945","Text":"648, and we\u0027ve been given a little hint here."},{"Start":"00:21.945 ","End":"00:25.260","Text":"Then in Part c, we\u0027ve been asked to check that the number"},{"Start":"00:25.260 ","End":"00:28.380","Text":"we expect is stored in myLong,"},{"Start":"00:28.380 ","End":"00:30.330","Text":"and in Part d,"},{"Start":"00:30.330 ","End":"00:36.060","Text":"then to store the maximum positive number that is possible into myLong."},{"Start":"00:36.060 ","End":"00:39.710","Text":"Then to speculate on what would happen in Part e,"},{"Start":"00:39.710 ","End":"00:43.280","Text":"if we were to add 1 to that value that we stored in Part d,"},{"Start":"00:43.280 ","End":"00:48.890","Text":"what would we expect to happen if we did add 1 to this maximum positive number possible?"},{"Start":"00:48.890 ","End":"00:51.695","Text":"We\u0027ve been asked in Part a to create"},{"Start":"00:51.695 ","End":"00:56.405","Text":"a new variable called myLong to store a long integer."},{"Start":"00:56.405 ","End":"00:59.765","Text":"That first part is pretty straightforward."},{"Start":"00:59.765 ","End":"01:02.389","Text":"Give the data type which is now going to be long,"},{"Start":"01:02.389 ","End":"01:06.215","Text":"not int or byte because it\u0027s a long integer,"},{"Start":"01:06.215 ","End":"01:09.360","Text":"which means it\u0027s got more memory,"},{"Start":"01:09.360 ","End":"01:11.850","Text":"so it can store a larger number."},{"Start":"01:11.850 ","End":"01:16.710","Text":"In Java, that will be 64 bits but it\u0027s a signed number,"},{"Start":"01:16.710 ","End":"01:19.880","Text":"so will be 63 bits."},{"Start":"01:19.880 ","End":"01:23.300","Text":"In terms of the size of the magnitude of"},{"Start":"01:23.300 ","End":"01:26.330","Text":"the number and one bit will be given up"},{"Start":"01:26.330 ","End":"01:30.215","Text":"to the fact that it\u0027s negative and positive numbers."},{"Start":"01:30.215 ","End":"01:34.655","Text":"Let\u0027s put my name identifier of this variable,"},{"Start":"01:34.655 ","End":"01:36.200","Text":"which I\u0027ve been asked to call it myLong."},{"Start":"01:36.200 ","End":"01:40.580","Text":"I\u0027m not going to put anything in there at the moment but it will"},{"Start":"01:40.580 ","End":"01:45.485","Text":"probably be initialized to 0 as before and so it is."},{"Start":"01:45.485 ","End":"01:47.150","Text":"Let\u0027s have a look at Part b,"},{"Start":"01:47.150 ","End":"01:51.180","Text":"which looks very straightforward and the same as what we\u0027ve seen before."},{"Start":"01:51.200 ","End":"01:59.670","Text":"Try and store into myLong 2147483648."},{"Start":"02:00.020 ","End":"02:02.755","Text":"Remember, we don\u0027t put any commas,"},{"Start":"02:02.755 ","End":"02:05.225","Text":"if we try to do that we\u0027d get an error."},{"Start":"02:05.225 ","End":"02:09.185","Text":"But obviously, when you\u0027re reading from worksheets and so on,"},{"Start":"02:09.185 ","End":"02:16.505","Text":"we find it easy to see the number or digits by separating them with commas and so on."},{"Start":"02:16.505 ","End":"02:19.100","Text":"Let\u0027s try that and see what happens."},{"Start":"02:19.100 ","End":"02:22.729","Text":"I get an error saying integer number too large."},{"Start":"02:22.729 ","End":"02:25.055","Text":"Now, why would that be the case?"},{"Start":"02:25.055 ","End":"02:29.449","Text":"When a long has much more bits"},{"Start":"02:29.449 ","End":"02:34.835","Text":"available and therefore should be able to store a much larger number than an int."},{"Start":"02:34.835 ","End":"02:42.515","Text":"You\u0027ll recall that we were able to store in an int 2147483647."},{"Start":"02:42.515 ","End":"02:47.645","Text":"Only very slightly smaller than this number that we\u0027ve been trying to make, one less."},{"Start":"02:47.645 ","End":"02:54.315","Text":"We\u0027ve just added 1 on and I\u0027ve got twice as much space to store in a long."},{"Start":"02:54.315 ","End":"02:56.300","Text":"Why would it be an error?"},{"Start":"02:56.300 ","End":"02:59.840","Text":"The answer is in the hint here for Part b."},{"Start":"02:59.840 ","End":"03:04.040","Text":"Because I\u0027ve typed in a number here,"},{"Start":"03:04.040 ","End":"03:07.430","Text":"it\u0027s assuming that I\u0027ve typed in an integer."},{"Start":"03:07.430 ","End":"03:12.470","Text":"Whenever you type a literal into the code pad and in fact,"},{"Start":"03:12.470 ","End":"03:13.970","Text":"in the Java system in general,"},{"Start":"03:13.970 ","End":"03:16.700","Text":"when I\u0027ve got that in a line of a program,"},{"Start":"03:16.700 ","End":"03:21.210","Text":"it assumes that literal is going to be an integer."},{"Start":"03:21.590 ","End":"03:23.840","Text":"It\u0027s basically saying, well,"},{"Start":"03:23.840 ","End":"03:30.230","Text":"I can\u0027t have an integer that big because integers can only be 31 bits long."},{"Start":"03:30.230 ","End":"03:33.649","Text":"What I have to do is I have to tell Java,"},{"Start":"03:33.649 ","End":"03:38.005","Text":"no, this literal is not an integer, it\u0027s a long."},{"Start":"03:38.005 ","End":"03:42.650","Text":"The thing that you need to do is simply stick an L"},{"Start":"03:42.650 ","End":"03:49.010","Text":"after the number and the L when it\u0027s picked up by the compiler or in the code pad,"},{"Start":"03:49.010 ","End":"03:55.385","Text":"in this instance, will indicate that this is a literal which is not an integer."},{"Start":"03:55.385 ","End":"03:57.215","Text":"It won\u0027t make that assumption anymore."},{"Start":"03:57.215 ","End":"04:04.585","Text":"It will say, this is still a literal but it\u0027s actually going to be interpreted as a long."},{"Start":"04:04.585 ","End":"04:06.815","Text":"If I press Enter now,"},{"Start":"04:06.815 ","End":"04:08.840","Text":"it\u0027s happy this time,"},{"Start":"04:08.840 ","End":"04:10.790","Text":"it doesn\u0027t give me an error message."},{"Start":"04:10.790 ","End":"04:14.345","Text":"It does successfully store this number."},{"Start":"04:14.345 ","End":"04:21.995","Text":"Literally, all I did was add the character L onto the end of this literal, L for long."},{"Start":"04:21.995 ","End":"04:24.860","Text":"It would work if it was a lowercase l as well,"},{"Start":"04:24.860 ","End":"04:27.380","Text":"by the way, but that looks a bit like a 1,"},{"Start":"04:27.380 ","End":"04:33.320","Text":"which is why I\u0027ve used the L. It\u0027s happy enough and it\u0027s stored this number,"},{"Start":"04:33.320 ","End":"04:38.450","Text":"which is only one larger than the maximum integer I could have stored in an integer."},{"Start":"04:38.450 ","End":"04:43.625","Text":"But it is larger and it is successfully stored into the variable."},{"Start":"04:43.625 ","End":"04:47.225","Text":"That\u0027s Part b, it looked deceptively simple."},{"Start":"04:47.225 ","End":"04:49.115","Text":"But for this little issue,"},{"Start":"04:49.115 ","End":"04:51.845","Text":"we\u0027ve explained why that happens."},{"Start":"04:51.845 ","End":"04:54.680","Text":"Essentially, all literals that you type"},{"Start":"04:54.680 ","End":"04:57.440","Text":"into a Java program are going to be assumed to be"},{"Start":"04:57.440 ","End":"05:04.200","Text":"integers unless you tell the system otherwise by sticking an L on the end."},{"Start":"05:04.200 ","End":"05:12.085","Text":"Great. What about the maximum positive number that we can store into myLong."},{"Start":"05:12.085 ","End":"05:13.620","Text":"Well, longs,"},{"Start":"05:13.620 ","End":"05:14.825","Text":"as we said before,"},{"Start":"05:14.825 ","End":"05:17.600","Text":"are stored in 64 bits."},{"Start":"05:17.600 ","End":"05:20.540","Text":"It\u0027s a 63-bit signed number,"},{"Start":"05:20.540 ","End":"05:29.243","Text":"so 2^63 is what I\u0027m looking for as the maximum number,"},{"Start":"05:29.243 ","End":"05:31.580","Text":"so let\u0027s think about what that might be."},{"Start":"05:31.580 ","End":"05:33.680","Text":"If I use the calculator,"},{"Start":"05:33.680 ","End":"05:36.470","Text":"I\u0027d find it\u0027s a huge number,"},{"Start":"05:36.470 ","End":"05:42.090","Text":"which I\u0027m going to type in, it\u0027ll be 9223372036854775808."},{"Start":"05:51.410 ","End":"05:55.730","Text":"That would have caused an error."},{"Start":"05:55.730 ","End":"05:57.500","Text":"I need to put the equal sign."},{"Start":"05:57.500 ","End":"06:02.720","Text":"However, remember that when we are dealing with a signed number and"},{"Start":"06:02.720 ","End":"06:08.390","Text":"the range in this complement is 2^n minus 1 on the negative side,"},{"Start":"06:08.390 ","End":"06:15.525","Text":"and 2^n minus 1 and that number should have 1 subtracted from it as well."},{"Start":"06:15.525 ","End":"06:19.785","Text":"I can\u0027t put 808 in but I can put 807 in."},{"Start":"06:19.785 ","End":"06:26.225","Text":"Again, I\u0027ve got to put an L on the end just to indicate that this is a long,"},{"Start":"06:26.225 ","End":"06:30.545","Text":"not an integer literal L, fantastic."},{"Start":"06:30.545 ","End":"06:33.000","Text":"It seems to have stored it."},{"Start":"06:33.000 ","End":"06:37.010","Text":"I\u0027ve got this incredibly a long series of digits,"},{"Start":"06:37.010 ","End":"06:38.540","Text":"hence the name long,"},{"Start":"06:38.540 ","End":"06:45.500","Text":"so I can store a much larger integer value into a long than I could into an integer."},{"Start":"06:45.500 ","End":"06:46.760","Text":"Remember in an integer,"},{"Start":"06:46.760 ","End":"06:54.070","Text":"the maximum positive value I could store was 2147483647,"},{"Start":"06:54.070 ","End":"06:56.255","Text":"1 less than this value."},{"Start":"06:56.255 ","End":"07:01.565","Text":"But now I\u0027ve got a massive number of digits that I\u0027ve been able to store."},{"Start":"07:01.565 ","End":"07:04.460","Text":"That is us done up to"},{"Start":"07:04.460 ","End":"07:11.015","Text":"Part d. We\u0027ve been asked the question if we add 1 to the value stored here,"},{"Start":"07:11.015 ","End":"07:13.955","Text":"what would we expect to happen?"},{"Start":"07:13.955 ","End":"07:17.330","Text":"Well, I hope you can guess what would happen but we could"},{"Start":"07:17.330 ","End":"07:21.485","Text":"actually try and add 1 to the value."},{"Start":"07:21.485 ","End":"07:24.860","Text":"If I put plus equal to 1 here,"},{"Start":"07:24.860 ","End":"07:30.030","Text":"I\u0027m going to add 1 to what is already stored in myLong and I\u0027m going to see what"},{"Start":"07:30.030 ","End":"07:35.000","Text":"happens and I assume the same thing is going to happen as what happened for integers,"},{"Start":"07:35.000 ","End":"07:37.340","Text":"and that they overflowed and we\u0027ve got"},{"Start":"07:37.340 ","End":"07:41.445","Text":"a large negative number and that\u0027s exactly what happened."},{"Start":"07:41.445 ","End":"07:45.920","Text":"I\u0027ve now seen the largest possible negative number that"},{"Start":"07:45.920 ","End":"07:50.210","Text":"can be stored in a long and it\u0027s that,"},{"Start":"07:50.210 ","End":"07:54.230","Text":"and the reason is exactly the same as the ones for integers."},{"Start":"07:54.230 ","End":"07:58.130","Text":"I\u0027ve overflowed the size I have available and"},{"Start":"07:58.130 ","End":"08:02.135","Text":"if I try and add 1 to the already highest value,"},{"Start":"08:02.135 ","End":"08:04.250","Text":"it goes into a negative value."},{"Start":"08:04.250 ","End":"08:06.275","Text":"The same thing happens with an integer."},{"Start":"08:06.275 ","End":"08:09.140","Text":"Even though a long can store a much larger number"},{"Start":"08:09.140 ","End":"08:12.525","Text":"even a long is eventually going to overflow,"},{"Start":"08:12.525 ","End":"08:15.710","Text":"so you always have to be aware of what"},{"Start":"08:15.710 ","End":"08:19.805","Text":"the maximum value is going to be stored in a variable."},{"Start":"08:19.805 ","End":"08:24.005","Text":"If you don\u0027t, you\u0027re going to have some strange effects on your program."},{"Start":"08:24.005 ","End":"08:29.420","Text":"That\u0027s us done with all of the different various types of integers."},{"Start":"08:29.420 ","End":"08:30.695","Text":"Actually, there\u0027s one missing,"},{"Start":"08:30.695 ","End":"08:34.055","Text":"but that will come up in the next video."},{"Start":"08:34.055 ","End":"08:37.590","Text":"I\u0027ll see you in that one. Thanks again."}],"ID":27345},{"Watched":false,"Name":"Exercise 5","Duration":"14m 4s","ChapterTopicVideoID":26437,"CourseChapterTopicPlaylistID":237669,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.400","Text":"Hey. Welcome back."},{"Start":"00:02.400 ","End":"00:06.735","Text":"We\u0027re going to work on a slightly more open-ended exercise this time."},{"Start":"00:06.735 ","End":"00:11.580","Text":"We\u0027ve been asked to create 4 more different variables using"},{"Start":"00:11.580 ","End":"00:13.995","Text":"the remaining primitives available in Java"},{"Start":"00:13.995 ","End":"00:17.280","Text":"that we haven\u0027t already used in the previous exercises."},{"Start":"00:17.280 ","End":"00:20.535","Text":"Then in part B, we\u0027ve been asked to give each variable"},{"Start":"00:20.535 ","End":"00:23.715","Text":"a sensible name and to use a mixture of styles."},{"Start":"00:23.715 ","End":"00:26.250","Text":"We know about camel case, snake case,"},{"Start":"00:26.250 ","End":"00:28.830","Text":"capital camel case, and capital snake case."},{"Start":"00:28.830 ","End":"00:31.980","Text":"We should try and use a mixture of those different styles"},{"Start":"00:31.980 ","End":"00:35.745","Text":"for each of those 4 different variables that we\u0027ll be creating."},{"Start":"00:35.745 ","End":"00:41.580","Text":"We\u0027ve also been asked to store values into each of those variables to see the effect."},{"Start":"00:41.580 ","End":"00:45.380","Text":"Then to try and cause an error by attempting to"},{"Start":"00:45.380 ","End":"00:49.700","Text":"store an illegal value in each of those variables."},{"Start":"00:49.700 ","End":"00:56.660","Text":"Let\u0027s start with 1 of the integer data types which we haven\u0027t used yet, which is short."},{"Start":"00:56.660 ","End":"00:59.105","Text":"The ones we have used are int,"},{"Start":"00:59.105 ","End":"01:00.860","Text":"which is 32 bits,"},{"Start":"01:00.860 ","End":"01:03.430","Text":"long, which is 64 bits,"},{"Start":"01:03.430 ","End":"01:05.535","Text":"byte, which is 8 bits,"},{"Start":"01:05.535 ","End":"01:08.855","Text":"short is between an integer and a byte,"},{"Start":"01:08.855 ","End":"01:10.835","Text":"so it\u0027s only 16 bits."},{"Start":"01:10.835 ","End":"01:14.035","Text":"The data type we need is short."},{"Start":"01:14.035 ","End":"01:16.050","Text":"Let\u0027s give it a name."},{"Start":"01:16.050 ","End":"01:20.240","Text":"I\u0027m going to use snake case, all lowercase."},{"Start":"01:20.240 ","End":"01:24.365","Text":"Remember, snake case is an underscore symbol used"},{"Start":"01:24.365 ","End":"01:29.670","Text":"to separate each word within the identifier of the variable name."},{"Start":"01:29.670 ","End":"01:32.310","Text":"For example, if I\u0027ve got a 2-player game,"},{"Start":"01:32.310 ","End":"01:34.440","Text":"I\u0027ve got Player 1 and Player 2,"},{"Start":"01:34.440 ","End":"01:36.750","Text":"I can call 1 of those variables,"},{"Start":"01:36.750 ","End":"01:41.045","Text":"player_one_score, if I need 2 variables to keep track of scores."},{"Start":"01:41.045 ","End":"01:45.350","Text":"There we go. That\u0027s creating the variable which is of"},{"Start":"01:45.350 ","End":"01:50.800","Text":"type short and has a identify a player_one_score."},{"Start":"01:51.710 ","End":"01:54.570","Text":"Let\u0027s give it some values."},{"Start":"01:54.570 ","End":"01:56.210","Text":"Because it\u0027s an integer,"},{"Start":"01:56.210 ","End":"01:58.450","Text":"I should be able to give it a number."},{"Start":"01:58.450 ","End":"02:03.090","Text":"I will need take out the short there first."},{"Start":"02:03.090 ","End":"02:07.760","Text":"There we go. Player_one_score is given a value of 1234, and it\u0027s quite happy with that."},{"Start":"02:07.760 ","End":"02:09.635","Text":"Let\u0027s try a bigger value."},{"Start":"02:09.635 ","End":"02:14.830","Text":"Straightaway, I hit an error because I\u0027ve presumably put"},{"Start":"02:14.830 ","End":"02:16.940","Text":"in a number that\u0027s too big and it is telling"},{"Start":"02:16.940 ","End":"02:19.520","Text":"us possible lossy conversion from int to short."},{"Start":"02:19.520 ","End":"02:20.750","Text":"As we saw before,"},{"Start":"02:20.750 ","End":"02:24.125","Text":"literals are assumed to be integers,"},{"Start":"02:24.125 ","End":"02:27.650","Text":"and that\u0027s why it always gives this type of error message when it\u0027s trying to convert"},{"Start":"02:27.650 ","End":"02:31.460","Text":"down the literal we\u0027ve typed in is assumed to be an int."},{"Start":"02:31.460 ","End":"02:37.415","Text":"In this case, we can\u0027t store an integer this large into 16 bits."},{"Start":"02:37.415 ","End":"02:40.085","Text":"Remember, it\u0027s 16 bits but it\u0027s signed,"},{"Start":"02:40.085 ","End":"02:46.455","Text":"so that means it\u0027s actually 15 bits and minus 1 in the positive direction."},{"Start":"02:46.455 ","End":"02:50.870","Text":"Remember, it\u0027s 2^n minus 1 on the negative side,"},{"Start":"02:50.870 ","End":"02:53.975","Text":"and it\u0027s 2^n minus 1 on the positive side."},{"Start":"02:53.975 ","End":"02:56.720","Text":"The biggest number I can actually represent"},{"Start":"02:56.720 ","End":"03:03.035","Text":"is the highest number I can store in 15 bits, which is 32767."},{"Start":"03:03.035 ","End":"03:05.910","Text":"Let\u0027s try that, and sure enough,"},{"Start":"03:05.910 ","End":"03:07.110","Text":"it\u0027s happy with that."},{"Start":"03:07.110 ","End":"03:11.250","Text":"Just to test it, I\u0027ll add 1 onto that to see if it complains,"},{"Start":"03:11.250 ","End":"03:12.585","Text":"and it does,"},{"Start":"03:12.585 ","End":"03:18.495","Text":"so I\u0027ve reached the limit of numbers I can store in a short."},{"Start":"03:18.495 ","End":"03:21.110","Text":"Let\u0027s try it in the negative direction."},{"Start":"03:21.110 ","End":"03:24.980","Text":"I should be out to store 32768 because remember I\u0027m allowed to"},{"Start":"03:24.980 ","End":"03:29.575","Text":"store 1 more in the negative direction than I can in the positive direction."},{"Start":"03:29.575 ","End":"03:31.340","Text":"It complains about that."},{"Start":"03:31.340 ","End":"03:33.530","Text":"Interesting because I\u0027ve got an extra,"},{"Start":"03:33.530 ","End":"03:37.205","Text":"extra digit in there that\u0027s better, 32768."},{"Start":"03:37.205 ","End":"03:41.120","Text":"There we go, 32768 on the negative side is fine."},{"Start":"03:41.120 ","End":"03:43.310","Text":"If I tried 32769,"},{"Start":"03:43.310 ","End":"03:47.225","Text":"it would complain, and it has."},{"Start":"03:47.225 ","End":"03:51.140","Text":"We\u0027ve done parts A to D for a short."},{"Start":"03:51.140 ","End":"03:54.460","Text":"Let\u0027s try for chars now."},{"Start":"03:54.460 ","End":"04:00.150","Text":"A char data type clearly starts with the data type which is called char."},{"Start":"04:00.150 ","End":"04:07.800","Text":"Now, let\u0027s use capital snake case for the variable name."},{"Start":"04:07.800 ","End":"04:13.235","Text":"It\u0027s all capitals, but I\u0027m still using under scores to separate the words."},{"Start":"04:13.235 ","End":"04:17.225","Text":"When you tend to use capitals snake case for constants,"},{"Start":"04:17.225 ","End":"04:19.985","Text":"something is not going to change in your program."},{"Start":"04:19.985 ","End":"04:23.060","Text":"Let\u0027s say we had a special char that we set up once at"},{"Start":"04:23.060 ","End":"04:26.300","Text":"the beginning of our program and it never changes again but I do"},{"Start":"04:26.300 ","End":"04:29.030","Text":"want it to store it in a variable just for"},{"Start":"04:29.030 ","End":"04:32.645","Text":"ease of reading my program and ease of maintaining it,"},{"Start":"04:32.645 ","End":"04:35.420","Text":"then it\u0027s a good convention to use."},{"Start":"04:35.420 ","End":"04:39.260","Text":"Most programs will do capital snake case in that."},{"Start":"04:39.260 ","End":"04:40.985","Text":"Here we go, special char,"},{"Start":"04:40.985 ","End":"04:42.170","Text":"and I can just put a char,"},{"Start":"04:42.170 ","End":"04:46.205","Text":"and note chars start with a single quote,"},{"Start":"04:46.205 ","End":"04:48.965","Text":"and then I can put the letter that I want to store."},{"Start":"04:48.965 ","End":"04:51.785","Text":"In fact, let me just define the variable first."},{"Start":"04:51.785 ","End":"04:53.660","Text":"There we go. There\u0027s my variable."},{"Start":"04:53.660 ","End":"04:58.100","Text":"Let us see what this default value is inside my variable. There we go."},{"Start":"04:58.100 ","End":"05:04.625","Text":"Is stored what\u0027s called a null character into special char by default in Java."},{"Start":"05:04.625 ","End":"05:09.681","Text":"In some languages, the null char is used to end the string,"},{"Start":"05:09.681 ","End":"05:12.260","Text":"so every string will end in a null char."},{"Start":"05:12.260 ","End":"05:16.925","Text":"That\u0027s just a character which has an integer value of 0."},{"Start":"05:16.925 ","End":"05:21.890","Text":"Now, let\u0027s actually store something in a variable. Here we go."},{"Start":"05:21.890 ","End":"05:23.090","Text":"I\u0027m going to store the letter a,"},{"Start":"05:23.090 ","End":"05:26.585","Text":"lowercase a, and it has no problem with that."},{"Start":"05:26.585 ","End":"05:28.370","Text":"Let\u0027s try A."},{"Start":"05:28.370 ","End":"05:29.930","Text":"No problem with that either."},{"Start":"05:29.930 ","End":"05:31.700","Text":"What if I put 2 letters?"},{"Start":"05:31.700 ","End":"05:34.490","Text":"Can\u0027t do that. It doesn\u0027t understand why I\u0027ve put"},{"Start":"05:34.490 ","End":"05:38.780","Text":"2 letters because obviously a char can only store 1 letter."},{"Start":"05:38.780 ","End":"05:41.915","Text":"It\u0027s a string that stores multiple letters."},{"Start":"05:41.915 ","End":"05:45.065","Text":"Then I go back to lowercase z, happy with that."},{"Start":"05:45.065 ","End":"05:47.740","Text":"Let\u0027s try another symbol like @,"},{"Start":"05:47.740 ","End":"05:49.370","Text":"it\u0027s happy with that as well."},{"Start":"05:49.370 ","End":"05:53.480","Text":"Even store non-printing symbols like newline,"},{"Start":"05:53.480 ","End":"05:58.170","Text":"which uses the escape code slash and then n. It\u0027s happy with that,"},{"Start":"05:58.170 ","End":"06:00.105","Text":"and t, it will do as well."},{"Start":"06:00.105 ","End":"06:02.960","Text":"Happy with that. I think I should be able to store"},{"Start":"06:02.960 ","End":"06:08.180","Text":"the null character like I had earlier, then that as well."},{"Start":"06:08.180 ","End":"06:11.180","Text":"Now, you\u0027ll notice here it\u0027s got a /u in front."},{"Start":"06:11.180 ","End":"06:14.690","Text":"That\u0027s the Unicode representation of a string."},{"Start":"06:14.690 ","End":"06:16.490","Text":"That\u0027s quite fun to play around with."},{"Start":"06:16.490 ","End":"06:19.445","Text":"If I try, it has to be /u,"},{"Start":"06:19.445 ","End":"06:23.060","Text":"and then what\u0027s going to follow is 4 hexadecimal digits,"},{"Start":"06:23.060 ","End":"06:27.140","Text":"and if I know a code for a particular character,"},{"Start":"06:27.140 ","End":"06:30.215","Text":"I can put in the Unicode value for that character."},{"Start":"06:30.215 ","End":"06:34.505","Text":"I happen to know that the UK pound symbol is"},{"Start":"06:34.505 ","End":"06:39.080","Text":"A3 in the Unicode character tables. Let\u0027s try that."},{"Start":"06:39.080 ","End":"06:43.220","Text":"Sure enough it\u0027s stored a pound symbol into special char."},{"Start":"06:43.220 ","End":"06:50.255","Text":"Now, you can obviously go up to very large 16-bit values here in this 4 characters."},{"Start":"06:50.255 ","End":"06:54.755","Text":"Let\u0027s try something a bit more esoteric."},{"Start":"06:54.755 ","End":"06:57.330","Text":"Let\u0027s try 266b,"},{"Start":"06:57.330 ","End":"07:00.025","Text":"happen to know is a special symbol."},{"Start":"07:00.025 ","End":"07:01.180","Text":"There we go."},{"Start":"07:01.180 ","End":"07:03.135","Text":"It\u0027s a musical symbol."},{"Start":"07:03.135 ","End":"07:05.805","Text":"Brilliant. That\u0027s char is done."},{"Start":"07:05.805 ","End":"07:09.440","Text":"I\u0027ve also managed to generate an error."},{"Start":"07:09.440 ","End":"07:12.605","Text":"Let me try 1 more. What if I put another symbol in here?"},{"Start":"07:12.605 ","End":"07:15.995","Text":"Rather than 4 hexadecimal characters,"},{"Start":"07:15.995 ","End":"07:19.890","Text":"let\u0027s put 5 hexadecimal characters and see what it says."},{"Start":"07:19.890 ","End":"07:21.915","Text":"Let\u0027s put 0 on the end of that."},{"Start":"07:21.915 ","End":"07:24.360","Text":"It basically doesn\u0027t understand it."},{"Start":"07:24.360 ","End":"07:27.665","Text":"It\u0027s saying that I think that\u0027s too long."},{"Start":"07:27.665 ","End":"07:34.800","Text":"When it says unclosed character literal here is expecting to see a closing quote,"},{"Start":"07:34.800 ","End":"07:37.950","Text":"but it sees a 0 instead basically saying,"},{"Start":"07:37.950 ","End":"07:39.900","Text":"I\u0027m getting too many characters."},{"Start":"07:39.900 ","End":"07:43.210","Text":"If I get rid of that one, it stops complaining."},{"Start":"07:43.210 ","End":"07:46.995","Text":"That\u0027s Part A-D done for a char."},{"Start":"07:46.995 ","End":"07:52.845","Text":"There\u0027s only 2 primitives left and they are the real number data types."},{"Start":"07:52.845 ","End":"07:57.750","Text":"In Java, those real number data types called float and double."},{"Start":"07:57.750 ","End":"08:02.145","Text":"Float uses 32 bits to store a floating point number,"},{"Start":"08:02.145 ","End":"08:06.945","Text":"and double uses 64 bits to store a floating point number."},{"Start":"08:06.945 ","End":"08:08.415","Text":"Let\u0027s go with that."},{"Start":"08:08.415 ","End":"08:10.560","Text":"Let\u0027s try float first."},{"Start":"08:10.560 ","End":"08:13.339","Text":"The datatype is float,"},{"Start":"08:13.339 ","End":"08:17.340","Text":"and let\u0027s give it a CamelCase name."},{"Start":"08:17.340 ","End":"08:21.270","Text":"CamelCase, remember is each new word starts"},{"Start":"08:21.270 ","End":"08:25.070","Text":"with a capital letter to separate the words out. There we go."},{"Start":"08:25.070 ","End":"08:27.575","Text":"I\u0027m going to call myFloat very boring,"},{"Start":"08:27.575 ","End":"08:28.985","Text":"not very descriptive names."},{"Start":"08:28.985 ","End":"08:31.355","Text":"I\u0027m not sure that\u0027s a great example, but there we go."},{"Start":"08:31.355 ","End":"08:35.220","Text":"myFloat, and I\u0027m going to give it a value now."},{"Start":"08:35.220 ","End":"08:36.975","Text":"Here we go with a value,"},{"Start":"08:36.975 ","End":"08:41.755","Text":"myFloat equals and let\u0027s give it this value."},{"Start":"08:41.755 ","End":"08:44.705","Text":"Immediately it complains, it\u0027s not happy."},{"Start":"08:44.705 ","End":"08:47.519","Text":"You might be a guest from the error message,"},{"Start":"08:47.519 ","End":"08:50.285","Text":"possible lossy conversion from double to float."},{"Start":"08:50.285 ","End":"08:52.440","Text":"We saw this with ints and shorts,"},{"Start":"08:52.440 ","End":"08:54.060","Text":"and ints and longs."},{"Start":"08:54.060 ","End":"08:56.345","Text":"So clearly it\u0027s assuming something,"},{"Start":"08:56.345 ","End":"09:01.015","Text":"is saying possible lossy conversion from double to float."},{"Start":"09:01.015 ","End":"09:07.775","Text":"The reason for that is I need to put an F after a literal,"},{"Start":"09:07.775 ","End":"09:09.325","Text":"if it\u0027s a floating point number,"},{"Start":"09:09.325 ","End":"09:12.935","Text":"or D, if it\u0027s a double precision number."},{"Start":"09:12.935 ","End":"09:17.680","Text":"It just needs to know because it can\u0027t tell unless I tell it whether this is"},{"Start":"09:17.680 ","End":"09:22.505","Text":"going to be a float or a double that you are typing in as a literal."},{"Start":"09:22.505 ","End":"09:25.695","Text":"Let\u0027s try that. Now it\u0027s perfectly happy."},{"Start":"09:25.695 ","End":"09:29.955","Text":"Let\u0027s just see how big we can go with this number."},{"Start":"09:29.955 ","End":"09:34.400","Text":"It seems to be able to store quite a few digits. Let\u0027s keep going."},{"Start":"09:34.400 ","End":"09:36.755","Text":"That seems to have stopped there."},{"Start":"09:36.755 ","End":"09:40.050","Text":"That might be something to do with the precision that\u0027s available."},{"Start":"09:40.050 ","End":"09:43.975","Text":"If you remember from the concepts video,"},{"Start":"09:43.975 ","End":"09:47.430","Text":"what we said was that there is a limit"},{"Start":"09:47.430 ","End":"09:51.420","Text":"to the smallest number that can be stored in a float,"},{"Start":"09:51.420 ","End":"09:57.930","Text":"and it\u0027s actually 1.4 times 10 to the minus 45, I think it was."},{"Start":"09:57.930 ","End":"09:59.650","Text":"So let\u0027s try that."},{"Start":"09:59.650 ","End":"10:02.220","Text":"Quite happy with 0.14."},{"Start":"10:02.220 ","End":"10:07.310","Text":"I can put 45 0s in front of this and it should be happy. Let\u0027s try that."},{"Start":"10:07.310 ","End":"10:09.590","Text":"Okay, brilliant, so it\u0027s happy with that."},{"Start":"10:09.590 ","End":"10:16.200","Text":"You\u0027ll see how the displays change to say 1.4E minus 45."},{"Start":"10:16.200 ","End":"10:19.915","Text":"That means 10 to the power minus 45."},{"Start":"10:19.915 ","End":"10:24.305","Text":"1.4 times 10 to the minus 45 is that number."},{"Start":"10:24.305 ","End":"10:27.020","Text":"If I try and put an extra 0 in,"},{"Start":"10:27.020 ","End":"10:29.315","Text":"I get this error message."},{"Start":"10:29.315 ","End":"10:33.885","Text":"It\u0027s a fairly clear one as error message go."},{"Start":"10:33.885 ","End":"10:39.770","Text":"It\u0027s basically saying, \"I can\u0027t store a number that small into a float.\""},{"Start":"10:39.770 ","End":"10:46.745","Text":"That we\u0027ve reached the limits of the smallest number that can be stored in a float."},{"Start":"10:46.745 ","End":"10:51.710","Text":"The final datatype then was a double."},{"Start":"10:51.710 ","End":"10:56.315","Text":"Let\u0027s create a variable for a double."},{"Start":"10:56.315 ","End":"11:00.090","Text":"We\u0027ll use capital camelCase this time."},{"Start":"11:00.090 ","End":"11:02.394","Text":"So I\u0027m going to call it MyDouble,"},{"Start":"11:02.394 ","End":"11:05.049","Text":"and you\u0027ll note the first letter has been capitalized."},{"Start":"11:05.049 ","End":"11:10.339","Text":"You tend not to use this in Java unless you\u0027re defining something called a class."},{"Start":"11:10.339 ","End":"11:12.675","Text":"But I\u0027m just doing it as an example here."},{"Start":"11:12.675 ","End":"11:14.603","Text":"There\u0027s my variable,"},{"Start":"11:14.603 ","End":"11:16.835","Text":"has been created now called MyDouble."},{"Start":"11:16.835 ","End":"11:19.865","Text":"Let\u0027s see what the value is and bet you can guess"},{"Start":"11:19.865 ","End":"11:22.890","Text":"what value is stored by default in there and"},{"Start":"11:22.890 ","End":"11:29.095","Text":"it\u0027s 0.0 because this is a floating point number with fractions."},{"Start":"11:29.095 ","End":"11:33.780","Text":"We should be able to happily store that very small number that we"},{"Start":"11:33.780 ","End":"11:39.090","Text":"saw before into MyDouble. Let\u0027s try that."},{"Start":"11:39.090 ","End":"11:41.940","Text":"Because I\u0027ve got an F on there, it\u0027s complaining."},{"Start":"11:41.940 ","End":"11:44.260","Text":"It\u0027s okay if I put a D. There we go."},{"Start":"11:44.260 ","End":"11:48.885","Text":"This time we are able to store 1.4 times 10 to the minus 46."},{"Start":"11:48.885 ","End":"11:50.830","Text":"Remember we couldn\u0027t do that in a float."},{"Start":"11:50.830 ","End":"11:55.930","Text":"We could get to 10 to the minus 45,"},{"Start":"11:55.930 ","End":"12:03.170","Text":"which we did up here successfully but we couldn\u0027t get an extra 0 in front there."},{"Start":"12:03.170 ","End":"12:06.720","Text":"However, we are able to do it when we store it in a double,"},{"Start":"12:06.720 ","End":"12:09.150","Text":"because we\u0027ve got way more digits,"},{"Start":"12:09.150 ","End":"12:12.070","Text":"we\u0027re using double the amount of space in memory to store"},{"Start":"12:12.070 ","End":"12:16.190","Text":"it but the actual number of 0s we can have in front is way more than double."},{"Start":"12:16.190 ","End":"12:21.060","Text":"In fact, I think it\u0027s 324."},{"Start":"12:21.060 ","End":"12:22.905","Text":"This is going to be interesting."},{"Start":"12:22.905 ","End":"12:26.100","Text":"We need 324 0s."},{"Start":"12:26.100 ","End":"12:29.695","Text":"So what I\u0027ll do is I\u0027ll copy and paste a lot of 0s from here."},{"Start":"12:29.695 ","End":"12:32.435","Text":"I\u0027ll do that,"},{"Start":"12:32.435 ","End":"12:36.170","Text":"let\u0027s do that maybe 20 times."},{"Start":"12:36.170 ","End":"12:37.805","Text":"See what we\u0027ve got now."},{"Start":"12:37.805 ","End":"12:41.755","Text":"Oops, so it is already complaining."},{"Start":"12:41.755 ","End":"12:44.000","Text":"Let\u0027s take some of those 0s out,"},{"Start":"12:44.000 ","End":"12:46.115","Text":"see what I can get away with."},{"Start":"12:46.115 ","End":"12:48.780","Text":"Still complaining. 32,"},{"Start":"12:48.780 ","End":"12:51.710","Text":"it\u0027s happy with, 79, it\u0027s happy with,"},{"Start":"12:51.710 ","End":"12:53.960","Text":"104, as I said,"},{"Start":"12:53.960 ","End":"12:59.480","Text":"it should be able to cope with 320 0s and more."},{"Start":"12:59.480 ","End":"13:05.235","Text":"199 now, 251, 94, 318."},{"Start":"13:05.235 ","End":"13:06.535","Text":"We\u0027re getting close to the limit now,"},{"Start":"13:06.535 ","End":"13:08.615","Text":"so let\u0027s count 19,"},{"Start":"13:08.615 ","End":"13:11.100","Text":"20, 21, 22,"},{"Start":"13:11.100 ","End":"13:13.945","Text":"23, was happy with that as well,"},{"Start":"13:13.945 ","End":"13:19.535","Text":"24, and we\u0027ve reached the limit there as we\u0027d expect."},{"Start":"13:19.535 ","End":"13:21.395","Text":"That\u0027s fantastic."},{"Start":"13:21.395 ","End":"13:23.700","Text":"We have now looked at"},{"Start":"13:23.700 ","End":"13:28.755","Text":"the 4 different datatypes that we hadn\u0027t used previously in the exercises."},{"Start":"13:28.755 ","End":"13:32.985","Text":"That was short, char, float, and double."},{"Start":"13:32.985 ","End":"13:36.280","Text":"We\u0027ve seen the values so we can store in there,"},{"Start":"13:36.280 ","End":"13:38.700","Text":"we can see the limits of the smallest values we can store"},{"Start":"13:38.700 ","End":"13:42.030","Text":"in to floats and doubles for example."},{"Start":"13:42.030 ","End":"13:44.795","Text":"Hopefully, that gives you an insight into"},{"Start":"13:44.795 ","End":"13:47.795","Text":"how we can make use of the different datatypes."},{"Start":"13:47.795 ","End":"13:50.615","Text":"If you wanted to play around a little bit longer in the code pad,"},{"Start":"13:50.615 ","End":"13:56.705","Text":"you might want to store some large values in floats and doubles to see the upper limits."},{"Start":"13:56.705 ","End":"13:58.580","Text":"That\u0027s it for this video."},{"Start":"13:58.580 ","End":"14:04.240","Text":"I\u0027ll see for the next set of exercises on Topic 4. See you then."}],"ID":27346}],"Thumbnail":null,"ID":237669},{"Name":"Assignment And Expressions","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"Assignment And Maths Operators","Duration":"8m 22s","ChapterTopicVideoID":26018,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.760","Text":"Hi everybody, welcome to this next video in which"},{"Start":"00:02.760 ","End":"00:06.120","Text":"we\u0027ll expand on our initial understanding of variables."},{"Start":"00:06.120 ","End":"00:07.710","Text":"By the end of this section,"},{"Start":"00:07.710 ","End":"00:11.475","Text":"you\u0027ll be able to understand the difference between declaration and assignment."},{"Start":"00:11.475 ","End":"00:15.600","Text":"Use the mathematical and comparison operators in an expression."},{"Start":"00:15.600 ","End":"00:19.500","Text":"Differentiate between the use of bitwise and logical operators."},{"Start":"00:19.500 ","End":"00:21.090","Text":"Describe the difference between"},{"Start":"00:21.090 ","End":"00:24.500","Text":"assignment and compound assignment operators and apply"},{"Start":"00:24.500 ","End":"00:28.249","Text":"your understanding of expressions and assignment in high-level languages."},{"Start":"00:28.249 ","End":"00:30.950","Text":"In the previous topic, we were introduced to the concept of"},{"Start":"00:30.950 ","End":"00:33.815","Text":"variables as a way of storing and retrieving data,"},{"Start":"00:33.815 ","End":"00:35.885","Text":"and the concept of a datatype,"},{"Start":"00:35.885 ","End":"00:39.230","Text":"which determines what can be done with a particular item of data."},{"Start":"00:39.230 ","End":"00:42.080","Text":"In a high-level language it is a formal process that"},{"Start":"00:42.080 ","End":"00:45.170","Text":"takes place when creating a variable and giving it a value."},{"Start":"00:45.170 ","End":"00:49.490","Text":"During variable declaration, we give a name more formerly known as"},{"Start":"00:49.490 ","End":"00:54.710","Text":"an identifier to the variable and we specify the datatype."},{"Start":"00:54.710 ","End":"00:57.005","Text":"Here the datatype shown in green,"},{"Start":"00:57.005 ","End":"00:59.134","Text":"and the identifier follows."},{"Start":"00:59.134 ","End":"01:03.500","Text":"Different datatypes as we know can have different memory requirements."},{"Start":"01:03.500 ","End":"01:05.920","Text":"These examples are in Java."},{"Start":"01:05.920 ","End":"01:09.920","Text":"Some languages don\u0027t require the datatype to be specified."},{"Start":"01:09.920 ","End":"01:12.290","Text":"Python being one example."},{"Start":"01:12.290 ","End":"01:14.434","Text":"Once a variable has been declared,"},{"Start":"01:14.434 ","End":"01:15.920","Text":"it can be given a value."},{"Start":"01:15.920 ","End":"01:19.535","Text":"This process is formerly known as variable assignment."},{"Start":"01:19.535 ","End":"01:22.625","Text":"In assignment, there are two halves of a statement,"},{"Start":"01:22.625 ","End":"01:29.194","Text":"with each half being separated by a symbol or symbols called an assignment operator."},{"Start":"01:29.194 ","End":"01:33.410","Text":"In most languages, this is a single equals sign."},{"Start":"01:33.410 ","End":"01:38.180","Text":"In some languages, it\u0027s a colon followed by an equal sign."},{"Start":"01:38.180 ","End":"01:40.445","Text":"The order is important."},{"Start":"01:40.445 ","End":"01:46.130","Text":"What you\u0027d expect is for the variable identifier to be on the left-hand side of"},{"Start":"01:46.130 ","End":"01:48.860","Text":"the assignment operator and the value to be"},{"Start":"01:48.860 ","End":"01:53.180","Text":"stored in the variable to be on the right-hand side of the assignment operator."},{"Start":"01:53.180 ","End":"01:55.025","Text":"In these two examples,"},{"Start":"01:55.025 ","End":"01:58.475","Text":"the variables have been assigned a value which is always the same"},{"Start":"01:58.475 ","End":"02:01.880","Text":"at the point it\u0027s encountered by the compiler or interpreter,"},{"Start":"02:01.880 ","End":"02:05.945","Text":"and hence we call this a literal constant assignment,"},{"Start":"02:05.945 ","End":"02:09.110","Text":"often abbreviated to just literal."},{"Start":"02:09.110 ","End":"02:12.380","Text":"We could instead put the name of a different variable on"},{"Start":"02:12.380 ","End":"02:15.805","Text":"the right-hand side of the assignment operator."},{"Start":"02:15.805 ","End":"02:20.330","Text":"What happens in this case is that the right-hand side is evaluated and"},{"Start":"02:20.330 ","End":"02:25.850","Text":"whatever value is returned goes into the variable on the left-hand side."},{"Start":"02:25.850 ","End":"02:31.324","Text":"Given that the right-hand side here is the identifier for a different variable,"},{"Start":"02:31.324 ","End":"02:35.270","Text":"evaluation is simply to return the contents of this variable."},{"Start":"02:35.270 ","End":"02:38.330","Text":"Running these two lines would result in the words input"},{"Start":"02:38.330 ","End":"02:41.930","Text":"your response being stored into both of the variables,"},{"Start":"02:41.930 ","End":"02:44.585","Text":"message 1 and message 2."},{"Start":"02:44.585 ","End":"02:47.240","Text":"In most languages, it\u0027s possible to combine"},{"Start":"02:47.240 ","End":"02:50.525","Text":"variable declaration and assignment in the same line."},{"Start":"02:50.525 ","End":"02:55.055","Text":"In fact, it\u0027s very common to give the variable an initial value when declaring it."},{"Start":"02:55.055 ","End":"02:57.800","Text":"We call that variable initialization."},{"Start":"02:57.800 ","End":"03:04.910","Text":"Here we declare the integer variable right left and giving it an initial value of 3."},{"Start":"03:04.910 ","End":"03:12.005","Text":"Likewise, the Boolean variable game completed is given an initial value of false."},{"Start":"03:12.005 ","End":"03:14.180","Text":"Once you\u0027ve declared this variable,"},{"Start":"03:14.180 ","End":"03:15.920","Text":"you don\u0027t need to declare it again,"},{"Start":"03:15.920 ","End":"03:19.370","Text":"but you can give it another variable with an assignment statement."},{"Start":"03:19.370 ","End":"03:23.360","Text":"In some languages, declaring a variable again could result in an error."},{"Start":"03:23.360 ","End":"03:25.010","Text":"In this example here,"},{"Start":"03:25.010 ","End":"03:29.240","Text":"we can see that tries has already been declared as an integer variable."},{"Start":"03:29.240 ","End":"03:31.655","Text":"We don\u0027t need to do that again and in fact,"},{"Start":"03:31.655 ","End":"03:33.455","Text":"if we did, we\u0027d probably get an error."},{"Start":"03:33.455 ","End":"03:36.770","Text":"To change the value of a variable already declared,"},{"Start":"03:36.770 ","End":"03:39.920","Text":"you drop the datatype before, in this case int,"},{"Start":"03:39.920 ","End":"03:44.865","Text":"and simply assign a new value using the operator assignment,"},{"Start":"03:44.865 ","End":"03:48.420","Text":"operator symbol, and the new value that you want to assign."},{"Start":"03:48.420 ","End":"03:52.675","Text":"Where assignments get more complex is when there\u0027s an expression involved."},{"Start":"03:52.675 ","End":"03:54.620","Text":"An expression is a statement that when"},{"Start":"03:54.620 ","End":"03:57.510","Text":"evaluated results in the computation of some value."},{"Start":"03:57.510 ","End":"04:00.050","Text":"We\u0027ve already come across the assignment operator,"},{"Start":"04:00.050 ","End":"04:02.014","Text":"which is equals in most languages,"},{"Start":"04:02.014 ","End":"04:04.895","Text":"expressions might use of other operators."},{"Start":"04:04.895 ","End":"04:13.265","Text":"For example, the most familiar basic maths operators are add, subtract, divide, multiply."},{"Start":"04:13.265 ","End":"04:16.040","Text":"The purpose of most of these operators are obvious although,"},{"Start":"04:16.040 ","End":"04:19.040","Text":"note the symbols are sometimes different."},{"Start":"04:19.040 ","End":"04:21.385","Text":"So divide is a forward slash,"},{"Start":"04:21.385 ","End":"04:24.900","Text":"multiply uses asterisk character,"},{"Start":"04:24.900 ","End":"04:27.005","Text":"which is shift and 8 on most keyboards."},{"Start":"04:27.005 ","End":"04:29.510","Text":"That\u0027s different to what we would do if we were writing"},{"Start":"04:29.510 ","End":"04:32.164","Text":"out a divide or a multiply operation."},{"Start":"04:32.164 ","End":"04:36.034","Text":"Modulo might be the only operator that\u0027s less obvious."},{"Start":"04:36.034 ","End":"04:40.325","Text":"It divides one integer by another and returns the remainder."},{"Start":"04:40.325 ","End":"04:43.189","Text":"In C#, Java, and Python,"},{"Start":"04:43.189 ","End":"04:46.490","Text":"the modulo operator is the percent symbol."},{"Start":"04:46.490 ","End":"04:51.500","Text":"The following examples are expressions that can be used in a program."},{"Start":"04:51.500 ","End":"04:56.210","Text":"If those expressions were assigned to a variable,"},{"Start":"04:56.210 ","End":"04:58.580","Text":"you\u0027d get a result of,"},{"Start":"04:58.580 ","End":"05:03.115","Text":"in this case, one being stored in the variable called result."},{"Start":"05:03.115 ","End":"05:09.540","Text":"In this example, 5 multiplied by 7 would store a result 35 into result,"},{"Start":"05:09.540 ","End":"05:13.290","Text":"15 divided by 3 would store 5 in results,"},{"Start":"05:13.290 ","End":"05:15.360","Text":"9 modulo 4,"},{"Start":"05:15.360 ","End":"05:22.485","Text":"would store 1 in result because 9 divided by 4 would give you 2 with a remainder of 1,"},{"Start":"05:22.485 ","End":"05:24.115","Text":"hence we store 1."},{"Start":"05:24.115 ","End":"05:26.915","Text":"That\u0027s what the modulo operator does."},{"Start":"05:26.915 ","End":"05:29.570","Text":"Expressions don\u0027t have to involve just literals,"},{"Start":"05:29.570 ","End":"05:31.475","Text":"they can also include variables."},{"Start":"05:31.475 ","End":"05:34.205","Text":"The first three lines here do involve literals,"},{"Start":"05:34.205 ","End":"05:36.274","Text":"but look at these last two lines."},{"Start":"05:36.274 ","End":"05:41.030","Text":"They use the expression on the right-hand side of the assignment operator to"},{"Start":"05:41.030 ","End":"05:46.220","Text":"evaluate a value which is then stored in the variable identified on the left-hand side."},{"Start":"05:46.220 ","End":"05:47.465","Text":"In the first case,"},{"Start":"05:47.465 ","End":"05:51.320","Text":"15 is stored into total because the value of"},{"Start":"05:51.320 ","End":"05:56.240","Text":"these 3 variables is computed by adding their content together."},{"Start":"05:56.240 ","End":"05:57.650","Text":"That currently 3, 5,"},{"Start":"05:57.650 ","End":"05:59.360","Text":"and 7 therefore,"},{"Start":"05:59.360 ","End":"06:01.940","Text":"15 would be stored into total."},{"Start":"06:01.940 ","End":"06:04.985","Text":"Average is assigned the value 5,"},{"Start":"06:04.985 ","End":"06:07.640","Text":"which is a contents of the total variable,"},{"Start":"06:07.640 ","End":"06:10.565","Text":"as we saw, is 15 divided by 3."},{"Start":"06:10.565 ","End":"06:13.250","Text":"Therefore, 5 is stored into average."},{"Start":"06:13.250 ","End":"06:16.400","Text":"These examples show one identifier on the left-hand"},{"Start":"06:16.400 ","End":"06:20.870","Text":"sided and one or more different identifies on the right-hand side."},{"Start":"06:20.870 ","End":"06:23.120","Text":"You could even use the same variable on"},{"Start":"06:23.120 ","End":"06:27.575","Text":"the left-hand side of the assignment operation and on the right-hand side."},{"Start":"06:27.575 ","End":"06:32.690","Text":"Here, we\u0027re referring to total on the left-hand side and on the right-hand side."},{"Start":"06:32.690 ","End":"06:37.745","Text":"So the expression is evaluated by adding to the current contents of total,"},{"Start":"06:37.745 ","End":"06:39.860","Text":"the literal value 1."},{"Start":"06:39.860 ","End":"06:44.075","Text":"If total already had 15 stored in it after this line runs,"},{"Start":"06:44.075 ","End":"06:49.385","Text":"total now store 16 due to this addition operation."},{"Start":"06:49.385 ","End":"06:55.559","Text":"The operators have an order of precedence similar to the standard mathematical order."},{"Start":"06:55.559 ","End":"06:57.050","Text":"Division, modulus,"},{"Start":"06:57.050 ","End":"06:59.405","Text":"and multiplication take place first,"},{"Start":"06:59.405 ","End":"07:01.865","Text":"followed by addition and subtraction."},{"Start":"07:01.865 ","End":"07:06.890","Text":"Here, division has a higher precedence than addition."},{"Start":"07:06.890 ","End":"07:10.115","Text":"So 15 will first be divided by 3,"},{"Start":"07:10.115 ","End":"07:13.360","Text":"then the results will be added to 15,"},{"Start":"07:13.360 ","End":"07:16.175","Text":"hence 20 is stored in the result."},{"Start":"07:16.175 ","End":"07:18.875","Text":"As brackets have the highest precedence,"},{"Start":"07:18.875 ","End":"07:21.260","Text":"they can be used in expressions to change"},{"Start":"07:21.260 ","End":"07:24.155","Text":"the exact order in which evaluation takes place."},{"Start":"07:24.155 ","End":"07:26.630","Text":"This line looks similar to the one above,"},{"Start":"07:26.630 ","End":"07:32.135","Text":"but forces 15 to be added to 15 before the division takes place,"},{"Start":"07:32.135 ","End":"07:36.465","Text":"hence result will have 10 stored in it in this case."},{"Start":"07:36.465 ","End":"07:41.735","Text":"Any operators that have equivalent precedence are evaluated from left to right."},{"Start":"07:41.735 ","End":"07:46.580","Text":"Here, divide and multiply are of the same order of precedence,"},{"Start":"07:46.580 ","End":"07:49.730","Text":"but divide is encountered by the compiler or"},{"Start":"07:49.730 ","End":"07:53.405","Text":"interpreter first so that operation happens first,"},{"Start":"07:53.405 ","End":"07:56.270","Text":"and the result is multiplied by 10,"},{"Start":"07:56.270 ","End":"07:58.085","Text":"giving the final result 50."},{"Start":"07:58.085 ","End":"08:02.480","Text":"Here subtraction and addition are also of equal precedence."},{"Start":"08:02.480 ","End":"08:08.150","Text":"Again, we proceed simply from left to right and 3 is subtracted from 15,"},{"Start":"08:08.150 ","End":"08:11.870","Text":"so 12 is then added to 4 and the result"},{"Start":"08:11.870 ","End":"08:15.905","Text":"ends up with a value 16 being assigned into result."},{"Start":"08:15.905 ","End":"08:19.730","Text":"We\u0027ll pause there now and in the next video we\u0027ll look at the comparison,"},{"Start":"08:19.730 ","End":"08:23.550","Text":"logical, and bitwise operators."}],"ID":26824},{"Watched":false,"Name":"Comparison Logical And Bitwise Operators","Duration":"13m 24s","ChapterTopicVideoID":26016,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.180","Text":"Hi, welcome back. In the previous video,"},{"Start":"00:03.180 ","End":"00:06.315","Text":"we looked at the assignment and mathematical operators."},{"Start":"00:06.315 ","End":"00:10.319","Text":"A different set of operators allow us to compare 2 values."},{"Start":"00:10.319 ","End":"00:13.080","Text":"Depending on the relationship between those 2 values,"},{"Start":"00:13.080 ","End":"00:16.860","Text":"the expression evaluates to true or false."},{"Start":"00:16.860 ","End":"00:21.105","Text":"Therefore, called comparison or relational operators."},{"Start":"00:21.105 ","End":"00:26.835","Text":"In most high-level languages the equal to comparison operator is a pair of equal signs,"},{"Start":"00:26.835 ","End":"00:28.850","Text":"not a single equal sign."},{"Start":"00:28.850 ","End":"00:34.220","Text":"This allows the compiler or interpreter to easily distinguish between an assignment,"},{"Start":"00:34.220 ","End":"00:35.795","Text":"which is a single equals,"},{"Start":"00:35.795 ","End":"00:37.190","Text":"and a comparison,"},{"Start":"00:37.190 ","End":"00:38.990","Text":"which is a double equals."},{"Start":"00:38.990 ","End":"00:42.770","Text":"Similarly, the not equals to operator is also a pair of"},{"Start":"00:42.770 ","End":"00:48.155","Text":"symbols with the exclamation mark followed by a single equal sign."},{"Start":"00:48.155 ","End":"00:51.035","Text":"Less than is a single symbol."},{"Start":"00:51.035 ","End":"00:55.354","Text":"The value on the left is compared to the value on the right."},{"Start":"00:55.354 ","End":"00:58.340","Text":"If the left-hand value is less,"},{"Start":"00:58.340 ","End":"01:00.185","Text":"it will return true."},{"Start":"01:00.185 ","End":"01:02.180","Text":"Less than or equals is the same,"},{"Start":"01:02.180 ","End":"01:05.060","Text":"but it will also return true if the 2 values being"},{"Start":"01:05.060 ","End":"01:09.390","Text":"compared either side of the operator are exactly equal."},{"Start":"01:09.390 ","End":"01:10.580","Text":"Greater than is similar."},{"Start":"01:10.580 ","End":"01:14.270","Text":"The value on the left is compared to the 1 on the right,"},{"Start":"01:14.270 ","End":"01:16.880","Text":"but this time the left side value has to be bigger"},{"Start":"01:16.880 ","End":"01:20.210","Text":"than the 1 on the right to return true."},{"Start":"01:20.210 ","End":"01:23.780","Text":"Greater than or equal to could be greater"},{"Start":"01:23.780 ","End":"01:27.560","Text":"than or exactly equal to the value on the right."},{"Start":"01:27.560 ","End":"01:31.265","Text":"Let\u0027s look at some examples where we compare 2 integers."},{"Start":"01:31.265 ","End":"01:36.830","Text":"We\u0027ll store the results of our expressions in a Boolean variable called result."},{"Start":"01:36.830 ","End":"01:40.849","Text":"Result will only ever contain the value true or false."},{"Start":"01:40.849 ","End":"01:43.820","Text":"In reality, we probably wouldn\u0027t do this in a real program."},{"Start":"01:43.820 ","End":"01:46.490","Text":"It\u0027d be more likely to be used as part of another statement."},{"Start":"01:46.490 ","End":"01:50.485","Text":"But we\u0027ll just do it this way to keep things simple for the moment."},{"Start":"01:50.485 ","End":"01:53.900","Text":"This next line looks a bit strange because we\u0027re"},{"Start":"01:53.900 ","End":"01:57.080","Text":"using a single equals for the assignment."},{"Start":"01:57.080 ","End":"02:00.620","Text":"Then a double equals for comparison."},{"Start":"02:00.620 ","End":"02:03.740","Text":"We\u0027ll get a value of false stored in result,"},{"Start":"02:03.740 ","End":"02:07.625","Text":"because the expression num1 equals num2"},{"Start":"02:07.625 ","End":"02:12.755","Text":"compares our 2 integer variables which are not equal."},{"Start":"02:12.755 ","End":"02:16.925","Text":"Therefore, the expression evaluates to false."},{"Start":"02:16.925 ","End":"02:22.790","Text":"The value false will be stored in variable results."},{"Start":"02:22.790 ","End":"02:24.440","Text":"In this next example,"},{"Start":"02:24.440 ","End":"02:27.980","Text":"the expression evaluates to true because the 2 integers"},{"Start":"02:27.980 ","End":"02:31.885","Text":"stored in num1 and num2 are not equal."},{"Start":"02:31.885 ","End":"02:35.570","Text":"If not true gets stored into result on this line."},{"Start":"02:35.570 ","End":"02:39.590","Text":"Now we\u0027re comparing 2 integers to see if 1 is greater than the other."},{"Start":"02:39.590 ","End":"02:44.465","Text":"In this case, num1 is storing a value greater than num2."},{"Start":"02:44.465 ","End":"02:46.730","Text":"What it\u0027s asking that question is it?"},{"Start":"02:46.730 ","End":"02:50.630","Text":"It isn\u0027t so because num1 is 3 and num2 is 5,"},{"Start":"02:50.630 ","End":"02:53.705","Text":"so this expression evaluates to false."},{"Start":"02:53.705 ","End":"03:00.485","Text":"However, if we do it the other way round and we say is num1 less than num2?"},{"Start":"03:00.485 ","End":"03:03.845","Text":"It will evaluate to true because in this case,"},{"Start":"03:03.845 ","End":"03:05.885","Text":"it obviously is true."},{"Start":"03:05.885 ","End":"03:12.200","Text":"Here we\u0027re comparing num2 to a literal value 5 to illustrate the point in"},{"Start":"03:12.200 ","End":"03:18.515","Text":"that greater than or equal to compares the values on the left and right of the operator,"},{"Start":"03:18.515 ","End":"03:22.295","Text":"and either 1 is bigger than the other or they\u0027re exactly equal."},{"Start":"03:22.295 ","End":"03:26.470","Text":"In this case they are equal so we\u0027ll get true."},{"Start":"03:26.470 ","End":"03:32.765","Text":"This expression will evaluate to true as well because although num1 is not less than 3,"},{"Start":"03:32.765 ","End":"03:36.170","Text":"it is exactly equal to 3."},{"Start":"03:36.170 ","End":"03:37.715","Text":"Hence, we\u0027ll get true."},{"Start":"03:37.715 ","End":"03:43.235","Text":"Another type of expression that evaluates to a Boolean result is the logical operation."},{"Start":"03:43.235 ","End":"03:48.275","Text":"In logical operations, Boolean inputs are used to generate a single Boolean output."},{"Start":"03:48.275 ","End":"03:53.570","Text":"In this case, logical AND expects both inputs to be true,"},{"Start":"03:53.570 ","End":"03:56.785","Text":"to return a result of true."},{"Start":"03:56.785 ","End":"04:05.430","Text":"Logical OR only expects 1 of the inputs to be true to return a value of true."},{"Start":"04:05.430 ","End":"04:12.005","Text":"Logical NOT just as the reverse of whatever the input was and compliments it."},{"Start":"04:12.005 ","End":"04:14.240","Text":"It\u0027s easy to understand with some examples."},{"Start":"04:14.240 ","End":"04:18.085","Text":"Let\u0027s say we have 2 Boolean variables, a and b."},{"Start":"04:18.085 ","End":"04:21.350","Text":"If we use the logical AND operator,"},{"Start":"04:21.350 ","End":"04:27.650","Text":"the result is false because AND wants both inputs to be true."},{"Start":"04:27.650 ","End":"04:30.590","Text":"In this case, only a is true."},{"Start":"04:30.590 ","End":"04:37.449","Text":"The evaluation will result in false being stored in result."},{"Start":"04:37.449 ","End":"04:39.465","Text":"However with OR,"},{"Start":"04:39.465 ","End":"04:43.085","Text":"only 1 or the other of the inputs needs to be true."},{"Start":"04:43.085 ","End":"04:45.515","Text":"In this case, a is true,"},{"Start":"04:45.515 ","End":"04:51.440","Text":"but b isn\u0027t, and that\u0027s fine with all so the results is true."},{"Start":"04:51.440 ","End":"04:55.400","Text":"Finally, note here there\u0027s only 1 value needed for"},{"Start":"04:55.400 ","End":"05:00.050","Text":"NOT in contrast the previous 2 which needed 2 values either side of the operator."},{"Start":"05:00.050 ","End":"05:05.090","Text":"The NOT operator flips the value that follows it to make it the opposite."},{"Start":"05:05.090 ","End":"05:08.450","Text":"In this case, b was false."},{"Start":"05:08.450 ","End":"05:11.545","Text":"But the NOT makes it true."},{"Start":"05:11.545 ","End":"05:14.600","Text":"That\u0027s what\u0027s stored in result here."},{"Start":"05:14.600 ","End":"05:17.540","Text":"What makes logical operations particularly useful is that"},{"Start":"05:17.540 ","End":"05:20.480","Text":"they can be used to evaluate multiple expressions,"},{"Start":"05:20.480 ","End":"05:23.720","Text":"so long as each expression evaluates to a Boolean."},{"Start":"05:23.720 ","End":"05:27.500","Text":"Here, we store the results of a comparison operation and"},{"Start":"05:27.500 ","End":"05:33.215","Text":"the variable result1 and another 1 in result2."},{"Start":"05:33.215 ","End":"05:39.140","Text":"The final outcome we\u0027re looking to determine is stored in a variable called outcome."},{"Start":"05:39.140 ","End":"05:44.779","Text":"It joins together the previous 2 expressions using the AND operator."},{"Start":"05:44.779 ","End":"05:48.125","Text":"Another way of writing that would be this."},{"Start":"05:48.125 ","End":"05:50.315","Text":"In both these lines,"},{"Start":"05:50.315 ","End":"05:55.050","Text":"num1 would have to be bigger than num2 and"},{"Start":"05:55.050 ","End":"05:56.960","Text":"num2 would have to be"},{"Start":"05:56.960 ","End":"06:02.365","Text":"smaller than 100 in order for a result of true to be stored in outcome."},{"Start":"06:02.365 ","End":"06:05.705","Text":"That\u0027s true of this line or this 1,"},{"Start":"06:05.705 ","End":"06:12.280","Text":"which simply uses these 2 expressions here in a third line."},{"Start":"06:12.280 ","End":"06:15.400","Text":"This is slightly more compact and you could"},{"Start":"06:15.400 ","End":"06:19.000","Text":"argue that maybe this is a little bit easier to read for a beginner."},{"Start":"06:19.000 ","End":"06:23.785","Text":"The conditional and logical operations always produce a Boolean output."},{"Start":"06:23.785 ","End":"06:27.925","Text":"A different type of operator can produce results on integers."},{"Start":"06:27.925 ","End":"06:34.540","Text":"The so-called bit-wise operators operate on 1 bit at a time when applied to 2 integers."},{"Start":"06:34.540 ","End":"06:39.730","Text":"The same operators exist as we previously saw for the logical operators."},{"Start":"06:39.730 ","End":"06:42.265","Text":"With the addition of a new 1."},{"Start":"06:42.265 ","End":"06:46.360","Text":"The bitwise exclusive OR works like an OR."},{"Start":"06:46.360 ","End":"06:50.980","Text":"But once exclusivity, if both the inputs are true,"},{"Start":"06:50.980 ","End":"06:52.915","Text":"it will give a false output."},{"Start":"06:52.915 ","End":"06:58.960","Text":"Unlike the regular OR which gives a true when both inputs are true."},{"Start":"06:58.960 ","End":"07:04.550","Text":"Here\u0027s an example of a variable assignment that uses a bitwise AND expression."},{"Start":"07:04.550 ","End":"07:08.840","Text":"It looks deceptively similar to the logical AND we saw earlier though,"},{"Start":"07:08.840 ","End":"07:12.020","Text":"note there\u0027s only 1 ampersand symbol here."},{"Start":"07:12.020 ","End":"07:16.120","Text":"But the bit-wise result also has a very different effect."},{"Start":"07:16.120 ","End":"07:20.375","Text":"It\u0027s easier to see when we look at 8 bit integers"},{"Start":"07:20.375 ","End":"07:24.425","Text":"expressed in binary when a bit wise AND is performed,"},{"Start":"07:24.425 ","End":"07:31.579","Text":"each respective bit in the 2 different integers is compared with an AND operation."},{"Start":"07:31.579 ","End":"07:34.790","Text":"The AND operation is performed on it and stored in"},{"Start":"07:34.790 ","End":"07:37.640","Text":"the result at the same position as we can see"},{"Start":"07:37.640 ","End":"07:44.940","Text":"here an AND requires 2 ones and the only place where we have 2 ones is in bit 8."},{"Start":"07:44.940 ","End":"07:48.055","Text":"Therefore the result, bit 8 is 1."},{"Start":"07:48.055 ","End":"07:53.929","Text":"Everywhere else has a 0 because nowhere do both of these 2 integer variables"},{"Start":"07:53.929 ","End":"08:00.510","Text":"have a 1 present at their equivalent bits except for bit 8."},{"Start":"08:00.510 ","End":"08:06.725","Text":"With bitwise OR any 1 of the 2 input bits can be a 1 to generate a 1 in the results,"},{"Start":"08:06.725 ","End":"08:09.680","Text":"or even both inputs can be 1 to generate a 1."},{"Start":"08:09.680 ","End":"08:13.910","Text":"The only combination that won\u0027t generate a 1 is 2 zeros,"},{"Start":"08:13.910 ","End":"08:15.815","Text":"which we see here in bit 5."},{"Start":"08:15.815 ","End":"08:17.690","Text":"But everywhere else, as you can see,"},{"Start":"08:17.690 ","End":"08:25.130","Text":"there\u0027s at least 1 1 in either int1 or int2 at every single bit position,"},{"Start":"08:25.130 ","End":"08:28.385","Text":"apart from, as we\u0027ve already said in bit 5."},{"Start":"08:28.385 ","End":"08:35.135","Text":"Contrast this with an exclusive OR which has the same result as an OR apart from when,"},{"Start":"08:35.135 ","End":"08:41.465","Text":"both inputs are 1 when the output is 0 and we see that here in a bit 8."},{"Start":"08:41.465 ","End":"08:46.040","Text":"We have a 1 here and a 1 here and exclusive OR doesn\u0027t like that."},{"Start":"08:46.040 ","End":"08:51.260","Text":"It makes it 0 here will also be a 0 because neither of the bits are 1."},{"Start":"08:51.260 ","End":"08:54.230","Text":"Everywhere else is fine because it has exclusivity."},{"Start":"08:54.230 ","End":"09:00.380","Text":"Only 1 of the bits at the relevant position is a 1, not both."},{"Start":"09:00.380 ","End":"09:04.145","Text":"The only places where that\u0027s not true is here where they\u0027re both 1,"},{"Start":"09:04.145 ","End":"09:06.650","Text":"therefore for exclusive OR it\u0027s a 0,"},{"Start":"09:06.650 ","End":"09:11.920","Text":"or they\u0027re both 0, which for OR and exclusive OR is always a 0."},{"Start":"09:11.920 ","End":"09:14.750","Text":"Finally, the bitwise complement operation flips"},{"Start":"09:14.750 ","End":"09:17.585","Text":"all the bits in the input so they\u0027re complimentary value."},{"Start":"09:17.585 ","End":"09:24.110","Text":"Everywhere where there was a 1 becomes a 0 as we see here."},{"Start":"09:24.110 ","End":"09:29.540","Text":"Everywhere where there was a 0 becomes a 1 as we see in these bits."},{"Start":"09:29.540 ","End":"09:32.300","Text":"The final type of operator commonly found in"},{"Start":"09:32.300 ","End":"09:35.795","Text":"high-level languages is the compound assignment operator."},{"Start":"09:35.795 ","End":"09:40.325","Text":"In this case, it takes the contents of variable num and adds"},{"Start":"09:40.325 ","End":"09:44.945","Text":"5 to it and then stores the result back into num."},{"Start":"09:44.945 ","End":"09:50.495","Text":"It\u0027s combining a mathematical operation with an assignment operation in 1 step."},{"Start":"09:50.495 ","End":"09:54.505","Text":"This is exactly equivalent to the following line,"},{"Start":"09:54.505 ","End":"09:57.850","Text":"where we have an expression on the right-hand side"},{"Start":"09:57.850 ","End":"10:01.705","Text":"saying add 5 to the current contents of num,"},{"Start":"10:01.705 ","End":"10:04.570","Text":"which is then stored back into num."},{"Start":"10:04.570 ","End":"10:09.280","Text":"As you can see, the compound assignment style is a little bit briefer."},{"Start":"10:09.280 ","End":"10:10.870","Text":"Although you could argue that"},{"Start":"10:10.870 ","End":"10:14.650","Text":"this longer version is a little bit easier to read for a beginner."},{"Start":"10:14.650 ","End":"10:17.470","Text":"In the most popular high-level languages,"},{"Start":"10:17.470 ","End":"10:19.600","Text":"all of the basic maths operators and"},{"Start":"10:19.600 ","End":"10:23.765","Text":"bitwise operators have a compound assignment equivalent."},{"Start":"10:23.765 ","End":"10:27.250","Text":"Here we will see some examples."},{"Start":"10:27.250 ","End":"10:29.980","Text":"There are also a pair of operators that you use to add or"},{"Start":"10:29.980 ","End":"10:33.039","Text":"subtract exactly 1 from variables."},{"Start":"10:33.039 ","End":"10:37.460","Text":"These are called the increment and decrement operators respectively."},{"Start":"10:37.460 ","End":"10:42.725","Text":"Here we are seeing num and the increment operator."},{"Start":"10:42.725 ","End":"10:48.215","Text":"The variable num will have 1 added to its current contents,"},{"Start":"10:48.215 ","End":"10:51.475","Text":"and then the result will be stored back into num."},{"Start":"10:51.475 ","End":"10:54.470","Text":"Decrement operator here would do the same thing,"},{"Start":"10:54.470 ","End":"11:00.500","Text":"but it would subtract 1 from num and store the value back into num."},{"Start":"11:00.500 ","End":"11:02.555","Text":"When you use an expression,"},{"Start":"11:02.555 ","End":"11:08.135","Text":"the increment and decrement operators can be used to pre-increment or post-increment."},{"Start":"11:08.135 ","End":"11:12.530","Text":"That means the value when used in the expression is changed before"},{"Start":"11:12.530 ","End":"11:17.240","Text":"the expression is evaluated or after the expression is evaluated."},{"Start":"11:17.240 ","End":"11:23.074","Text":"Here we\u0027re going to use the compound assignment operator and the increment operator."},{"Start":"11:23.074 ","End":"11:27.560","Text":"On the right-hand side of this compound assignment operation is"},{"Start":"11:27.560 ","End":"11:32.075","Text":"an expression which is evaluated first before the assignment takes place."},{"Start":"11:32.075 ","End":"11:40.365","Text":"What happens is that num1 is added to what is in int1 and stored back into int1."},{"Start":"11:40.365 ","End":"11:44.630","Text":"Int1 will have 15 stored into it after this line runs."},{"Start":"11:44.630 ","End":"11:48.110","Text":"With post-increment, after that evaluation"},{"Start":"11:48.110 ","End":"11:51.845","Text":"of the expression has happened, the increment happens."},{"Start":"11:51.845 ","End":"11:53.990","Text":"Once the line has finished,"},{"Start":"11:53.990 ","End":"11:57.295","Text":"num1 will contain 11."},{"Start":"11:57.295 ","End":"11:59.610","Text":"Previously it contained 10."},{"Start":"11:59.610 ","End":"12:01.609","Text":"When the expression was evaluated,"},{"Start":"12:01.609 ","End":"12:06.350","Text":"it would have been 10 hence 10 was added to 5,"},{"Start":"12:06.350 ","End":"12:09.200","Text":"and int1 had 15 stored in it."},{"Start":"12:09.200 ","End":"12:13.520","Text":"However, at the end of the line after the assignment had taken place,"},{"Start":"12:13.520 ","End":"12:16.820","Text":"num1 would have been incremented because this is a post-increment."},{"Start":"12:16.820 ","End":"12:22.145","Text":"Then for num1 would store 11 once the line has finished running."},{"Start":"12:22.145 ","End":"12:27.260","Text":"Contrast that with pre-increment where the increment happens first,"},{"Start":"12:27.260 ","End":"12:29.630","Text":"then the expression is evaluated."},{"Start":"12:29.630 ","End":"12:33.215","Text":"Here, num2 will be incremented first."},{"Start":"12:33.215 ","End":"12:39.365","Text":"Then the expression will be evaluated giving 11 as that\u0027s what\u0027s now stored in num2."},{"Start":"12:39.365 ","End":"12:41.855","Text":"Then the compound assignment happens,"},{"Start":"12:41.855 ","End":"12:49.480","Text":"which increases in 2 by 11 and stores the result 16 back into int2."},{"Start":"12:49.480 ","End":"12:54.485","Text":"In this section, we learned how to distinguish between declaration and assignment."},{"Start":"12:54.485 ","End":"12:58.024","Text":"Use a mathematical and comparison operators in an expression."},{"Start":"12:58.024 ","End":"13:02.015","Text":"Differentiate between the use of bitwise and logical operators."},{"Start":"13:02.015 ","End":"13:06.800","Text":"Describe the difference between assignment and compound assignment operators."},{"Start":"13:06.800 ","End":"13:11.195","Text":"Apply your understanding of expressions and assignment in high-level languages."},{"Start":"13:11.195 ","End":"13:15.500","Text":"That\u0027s it for now, be sure to try the exercises to apply what you\u0027ve learned."},{"Start":"13:15.500 ","End":"13:18.860","Text":"I\u0027ll see you in the next section where we\u0027ll look at how to control"},{"Start":"13:18.860 ","End":"13:22.520","Text":"the order in which instructions are executed."},{"Start":"13:22.520 ","End":"13:24.810","Text":"Thanks and see you soon.2"}],"ID":26825},{"Watched":false,"Name":"Exercise 1","Duration":"4m 54s","ChapterTopicVideoID":26432,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.760","Text":"Hello. Welcome to this first video where we work through"},{"Start":"00:02.760 ","End":"00:06.045","Text":"the first exercise on assignments and expressions,"},{"Start":"00:06.045 ","End":"00:09.990","Text":"aiming to build on our initial understanding of variables and data types."},{"Start":"00:09.990 ","End":"00:15.180","Text":"We, first of all, been asked to create a new project and open the Code Pad in Bluej,"},{"Start":"00:15.180 ","End":"00:17.925","Text":"and then to do the following activities in the Code Pad."},{"Start":"00:17.925 ","End":"00:22.230","Text":"In part A, we need to create a single line of code to create a Boolean variable,"},{"Start":"00:22.230 ","End":"00:24.510","Text":"and to call that variable is valid,"},{"Start":"00:24.510 ","End":"00:27.345","Text":"and to initialize it with the value true."},{"Start":"00:27.345 ","End":"00:32.040","Text":"Part B, we\u0027re asked to use the up arrow to retrieve the line we just typed in,"},{"Start":"00:32.040 ","End":"00:36.650","Text":"and to change the last part of the line so the value is false, not true,"},{"Start":"00:36.650 ","End":"00:42.495","Text":"and then explain why we get an error message when you press \"Enter\" to compile a line."},{"Start":"00:42.495 ","End":"00:44.210","Text":"Then finally in part C,"},{"Start":"00:44.210 ","End":"00:49.730","Text":"we\u0027re asked to correct that line to successfully change the value to false."},{"Start":"00:49.730 ","End":"00:52.250","Text":"Welcome to this first video where we work through"},{"Start":"00:52.250 ","End":"00:55.670","Text":"the exercise on expressions and assignments."},{"Start":"00:55.670 ","End":"00:59.150","Text":"Exercise 1 specifically with the aim of building on"},{"Start":"00:59.150 ","End":"01:02.660","Text":"our initial understanding of variables and data types."},{"Start":"01:02.660 ","End":"01:07.505","Text":"We\u0027ve been first asked in exercise 1 to create a new project."},{"Start":"01:07.505 ","End":"01:09.740","Text":"Open the Code Pad, as we know from before,"},{"Start":"01:09.740 ","End":"01:16.010","Text":"you cannot have a Code Pad unless you have a project to contain it within."},{"Start":"01:16.010 ","End":"01:20.600","Text":"We\u0027ll just give it a name and I can open up"},{"Start":"01:20.600 ","End":"01:26.210","Text":"the window here just to give myself a bit of space to see the responses, etc."},{"Start":"01:26.210 ","End":"01:30.500","Text":"What we\u0027ve been asked to do in part 1 is with a single line of code,"},{"Start":"01:30.500 ","End":"01:36.400","Text":"create a Boolean variable called is valid and to initialize it with the value true."},{"Start":"01:36.400 ","End":"01:38.840","Text":"As we know from previously,"},{"Start":"01:38.840 ","End":"01:41.390","Text":"to declare a variable in Java,"},{"Start":"01:41.390 ","End":"01:44.345","Text":"you need to state the data type first."},{"Start":"01:44.345 ","End":"01:46.190","Text":"In this case, it\u0027s Boolean,"},{"Start":"01:46.190 ","End":"01:48.997","Text":"then the identifier or the name,"},{"Start":"01:48.997 ","End":"01:53.075","Text":"in this case, we\u0027ve been asked to call it is valid in camel case."},{"Start":"01:53.075 ","End":"01:56.000","Text":"Then we\u0027ve been asked to initialize it with the value true."},{"Start":"01:56.000 ","End":"01:57.590","Text":"Now up until now,"},{"Start":"01:57.590 ","End":"02:01.565","Text":"we would\u0027ve ended this line with a semicolon or by pressing \"Enter\","},{"Start":"02:01.565 ","End":"02:03.320","Text":"and we wouldn\u0027t have given it a value."},{"Start":"02:03.320 ","End":"02:08.520","Text":"But now we\u0027ve been asked to assign a value whilst we are declaring the variables,"},{"Start":"02:08.520 ","End":"02:09.990","Text":"so we can go ahead and do that,"},{"Start":"02:09.990 ","End":"02:12.410","Text":"and we have been asked to give it valid true,"},{"Start":"02:12.410 ","End":"02:14.780","Text":"which in Java is all lowercase."},{"Start":"02:14.780 ","End":"02:17.990","Text":"Let\u0027s do that. I\u0027m going to put semicolon on the end as well,"},{"Start":"02:17.990 ","End":"02:20.850","Text":"because that\u0027s how lines should end."},{"Start":"02:21.290 ","End":"02:28.580","Text":"No problems there, it\u0027s created my variable and I can check if I want that the value"},{"Start":"02:28.580 ","End":"02:34.880","Text":"in there is what I expect and is indeed true and is all data type Boolean,"},{"Start":"02:34.880 ","End":"02:36.710","Text":"so it\u0027s done its job and I\u0027m going to expect"},{"Start":"02:36.710 ","End":"02:39.350","Text":"anything else because it\u0027s such a simple line of code."},{"Start":"02:39.350 ","End":"02:41.480","Text":"Now we\u0027ve been asked in part B to press"},{"Start":"02:41.480 ","End":"02:44.840","Text":"the up arrow key to true treat the line we just typed to."},{"Start":"02:44.840 ","End":"02:48.020","Text":"It would be this line that we just typed to and obviously,"},{"Start":"02:48.020 ","End":"02:49.670","Text":"you\u0027ve looked at a value if is valid as well,"},{"Start":"02:49.670 ","End":"02:50.780","Text":"so I\u0027ve skipped the overlap,"},{"Start":"02:50.780 ","End":"02:53.180","Text":"but here is the initial line and we\u0027ve just been"},{"Start":"02:53.180 ","End":"02:55.865","Text":"asked to change the value to false so I\u0027ll do that."},{"Start":"02:55.865 ","End":"03:00.590","Text":"Now we get an error message saying is valid is already defined."},{"Start":"03:00.590 ","End":"03:04.640","Text":"We\u0027ve been asked to explain why we get that error message."},{"Start":"03:04.640 ","End":"03:06.920","Text":"Was actually relatively straightforward."},{"Start":"03:06.920 ","End":"03:10.310","Text":"As we said, when you declare a variable in Java,"},{"Start":"03:10.310 ","End":"03:13.940","Text":"you need to give a data type and you can also assign a value."},{"Start":"03:13.940 ","End":"03:19.235","Text":"Now what we\u0027re trying to do is presumably assign a different value to this variable."},{"Start":"03:19.235 ","End":"03:22.940","Text":"What we cannot do is redefine the variable because"},{"Start":"03:22.940 ","End":"03:26.735","Text":"that\u0027s what we appear to be doing as far as Java is concerned."},{"Start":"03:26.735 ","End":"03:28.805","Text":"It\u0027s saying is valid is already defined"},{"Start":"03:28.805 ","End":"03:32.270","Text":"because we put the data type in front of is valid,"},{"Start":"03:32.270 ","End":"03:36.875","Text":"it assumes we\u0027re declaring a new variable called is valid,"},{"Start":"03:36.875 ","End":"03:39.755","Text":"but it already has a variable called is valid,"},{"Start":"03:39.755 ","End":"03:43.790","Text":"so refuses to let us do that and hence the error message."},{"Start":"03:43.790 ","End":"03:47.600","Text":"What I need to do to correct this for part C is I simply need to"},{"Start":"03:47.600 ","End":"03:51.455","Text":"remove the data type from the beginning."},{"Start":"03:51.455 ","End":"03:56.220","Text":"Now it understands that there is an existing variable called is valid,"},{"Start":"03:56.220 ","End":"03:58.480","Text":"is not declaring a new one and it just"},{"Start":"03:58.480 ","End":"04:01.495","Text":"wants to change the value of that existing variable."},{"Start":"04:01.495 ","End":"04:04.270","Text":"I\u0027ll go ahead and do that and no error this time"},{"Start":"04:04.270 ","End":"04:06.940","Text":"and if I look at the value of is valid again,"},{"Start":"04:06.940 ","End":"04:08.755","Text":"it is indeed false now,"},{"Start":"04:08.755 ","End":"04:10.405","Text":"whereas previously it was true."},{"Start":"04:10.405 ","End":"04:12.490","Text":"A very, very simple exercise,"},{"Start":"04:12.490 ","End":"04:16.330","Text":"but really just there to illustrate the difference between"},{"Start":"04:16.330 ","End":"04:20.320","Text":"declaring a variable and assigning a value to a variable."},{"Start":"04:20.320 ","End":"04:23.560","Text":"They\u0027re different things, although we can do both things on"},{"Start":"04:23.560 ","End":"04:28.180","Text":"one line as we did here and as we attempted to do here,"},{"Start":"04:28.180 ","End":"04:31.085","Text":"but we couldn\u0027t because the variable already existed so"},{"Start":"04:31.085 ","End":"04:34.165","Text":"this is an error that a beginner will quite often get."},{"Start":"04:34.165 ","End":"04:38.440","Text":"They\u0027ll forget to take the data type off the beginning when they\u0027re merely"},{"Start":"04:38.440 ","End":"04:43.495","Text":"assigning a new value to a variable that already exists."},{"Start":"04:43.495 ","End":"04:45.700","Text":"Hopefully, that makes sense now,"},{"Start":"04:45.700 ","End":"04:49.790","Text":"and I\u0027ll see you in the next exercise where we start working with"},{"Start":"04:49.790 ","End":"04:55.350","Text":"assignments of variables to other variables. I\u0027ll see you then."}],"ID":27334},{"Watched":false,"Name":"Exercise 2","Duration":"4m 29s","ChapterTopicVideoID":26433,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.725","Text":"Hello, welcome back."},{"Start":"00:01.725 ","End":"00:05.340","Text":"In this next exercise on assignment and expressions,"},{"Start":"00:05.340 ","End":"00:08.430","Text":"we\u0027ve been asked to within the same Code Pad as before,"},{"Start":"00:08.430 ","End":"00:10.395","Text":"create 2 integer variables,"},{"Start":"00:10.395 ","End":"00:13.260","Text":"num1 and num2 with no initial value given,"},{"Start":"00:13.260 ","End":"00:18.230","Text":"and then to assign the value 10 to num1."},{"Start":"00:18.230 ","End":"00:22.775","Text":"Then in part c, to assign the contents of num1 to num2."},{"Start":"00:22.775 ","End":"00:24.020","Text":"Then finally in part d,"},{"Start":"00:24.020 ","End":"00:28.775","Text":"to confirm the contents of num2 are what you would expect."},{"Start":"00:28.775 ","End":"00:32.360","Text":"We\u0027ve been asked to create 2 integer variables num1 and"},{"Start":"00:32.360 ","End":"00:36.495","Text":"num2 with no initial value given in part a."},{"Start":"00:36.495 ","End":"00:38.430","Text":"Let\u0027s go ahead and do that."},{"Start":"00:38.430 ","End":"00:41.130","Text":"It turns out there\u0027s a little trick you can do."},{"Start":"00:41.130 ","End":"00:44.000","Text":"If there are 2 variables that you want to declare,"},{"Start":"00:44.000 ","End":"00:45.905","Text":"you can declare them in 1 line,"},{"Start":"00:45.905 ","End":"00:48.350","Text":"so long as they are the same data type,"},{"Start":"00:48.350 ","End":"00:51.245","Text":"because both of these are int,"},{"Start":"00:51.245 ","End":"00:57.430","Text":"we can do that and you just simply separate the 2 variable names with a comma."},{"Start":"00:57.430 ","End":"01:02.160","Text":"It will happily declare both of those variables in 1 line,"},{"Start":"01:02.160 ","End":"01:03.740","Text":"I could do in 2 if I wanted to,"},{"Start":"01:03.740 ","End":"01:07.925","Text":"but I\u0027m just going to show you that it will work if you do it in 1 line."},{"Start":"01:07.925 ","End":"01:10.145","Text":"Just to prove that that\u0027s worked."},{"Start":"01:10.145 ","End":"01:16.430","Text":"Well, I just get num1\u0027s value is 0 and num2\u0027s value is also 0."},{"Start":"01:16.430 ","End":"01:18.740","Text":"That\u0027s what this message here is saying."},{"Start":"01:18.740 ","End":"01:21.995","Text":"By the way, it\u0027s always actually good practice to"},{"Start":"01:21.995 ","End":"01:25.700","Text":"assign a value to a variable when you declare it,"},{"Start":"01:25.700 ","End":"01:28.700","Text":"even if it will be given a default value,"},{"Start":"01:28.700 ","End":"01:33.275","Text":"you sometimes can\u0027t guarantee that on certain systems,"},{"Start":"01:33.275 ","End":"01:36.590","Text":"so its best practice is to actually always assign"},{"Start":"01:36.590 ","End":"01:41.285","Text":"a value to a variable when you\u0027re initially declaring it."},{"Start":"01:41.285 ","End":"01:43.760","Text":"That\u0027s the first part, part a."},{"Start":"01:43.760 ","End":"01:48.070","Text":"Then in part b, we\u0027ve been asked to assign the value 10 to num1."},{"Start":"01:48.070 ","End":"01:50.780","Text":"Remembering what we learned in the previous exercise,"},{"Start":"01:50.780 ","End":"01:52.865","Text":"I don\u0027t need to put the data type again."},{"Start":"01:52.865 ","End":"01:56.105","Text":"I simply need to write the variable name out."},{"Start":"01:56.105 ","End":"02:02.195","Text":"Num1 equals 10 is what I\u0027ve been asked to do and it\u0027s quite happy doing that."},{"Start":"02:02.195 ","End":"02:05.000","Text":"But part c is something we haven\u0027t seen before,"},{"Start":"02:05.000 ","End":"02:09.710","Text":"it\u0027s asking us to assign the contents of num1 to num2."},{"Start":"02:09.710 ","End":"02:14.630","Text":"Previously, we\u0027ve only ever assigned literal values to variables."},{"Start":"02:14.630 ","End":"02:19.500","Text":"Now, we\u0027re being asked to assign the contents of a variable to another variable so,"},{"Start":"02:19.500 ","End":"02:23.640","Text":"really, all we need to do here is understand which order we put things in."},{"Start":"02:23.640 ","End":"02:29.840","Text":"You\u0027ll remember from the video that we are supposed to put on the left-hand side,"},{"Start":"02:29.840 ","End":"02:33.904","Text":"the name of the variable that we wanted to store things into."},{"Start":"02:33.904 ","End":"02:38.465","Text":"Here, we\u0027ve been asked to assign the contents of num1 to num2."},{"Start":"02:38.465 ","End":"02:42.235","Text":"Num2 should go on the left-hand side here,"},{"Start":"02:42.235 ","End":"02:44.390","Text":"then follows the assignment operator,"},{"Start":"02:44.390 ","End":"02:47.705","Text":"which in Java is a single equals,"},{"Start":"02:47.705 ","End":"02:52.915","Text":"and then num1 is the value we want to assign to num2."},{"Start":"02:52.915 ","End":"02:55.500","Text":"I\u0027ll go ahead and do that, and it\u0027s done."},{"Start":"02:55.500 ","End":"02:58.790","Text":"It reflects back to me 10 I\u0027m not sure what is 10,"},{"Start":"02:58.790 ","End":"03:00.050","Text":"is it num1 or is it num2?"},{"Start":"03:00.050 ","End":"03:01.925","Text":"Let\u0027s have a look at the value of num2."},{"Start":"03:01.925 ","End":"03:03.375","Text":"Num2 is 10,"},{"Start":"03:03.375 ","End":"03:09.480","Text":"and we already know that num1 is 10 because we set its value over here."},{"Start":"03:09.480 ","End":"03:12.885","Text":"Now, num2 and num1 are 10."},{"Start":"03:12.885 ","End":"03:15.630","Text":"That\u0027s pretty much what we expect."},{"Start":"03:15.630 ","End":"03:22.715","Text":"All we\u0027ve really learned here is when you put the contents of 1 variable into another,"},{"Start":"03:22.715 ","End":"03:27.655","Text":"you get a copy of the variable value."},{"Start":"03:27.655 ","End":"03:31.060","Text":"It does not affect the value you\u0027re copying in."},{"Start":"03:31.060 ","End":"03:35.050","Text":"In this case, we were copying num1 into num2."},{"Start":"03:35.050 ","End":"03:37.165","Text":"Num2 got num1 value,"},{"Start":"03:37.165 ","End":"03:39.430","Text":"but num1 didn\u0027t change itself."},{"Start":"03:39.430 ","End":"03:43.720","Text":"You might think that when you\u0027re assigning a value from 1 variable to another,"},{"Start":"03:43.720 ","End":"03:45.655","Text":"you\u0027re removing the value somehow,"},{"Start":"03:45.655 ","End":"03:46.840","Text":"but you\u0027re not doing that."},{"Start":"03:46.840 ","End":"03:51.280","Text":"You\u0027re just producing a copy of the value and the copy of that value goes"},{"Start":"03:51.280 ","End":"03:57.175","Text":"into the variable on the left-hand side of the assignment operator."},{"Start":"03:57.175 ","End":"04:00.700","Text":"We\u0027ll do some more complex operations later on."},{"Start":"04:00.700 ","End":"04:04.645","Text":"But that\u0027s the most basic type of assignment of 1 variable to another."},{"Start":"04:04.645 ","End":"04:08.290","Text":"Essentially, we\u0027re evaluating an expression on the right-hand side"},{"Start":"04:08.290 ","End":"04:12.530","Text":"and because the expression simply contains the name of a variable,"},{"Start":"04:12.530 ","End":"04:16.815","Text":"the evaluation is just to give us the contents of that variable."},{"Start":"04:16.815 ","End":"04:22.355","Text":"Then the assignment then happens and it\u0027s stored into the variable on the left-hand side."},{"Start":"04:22.355 ","End":"04:24.545","Text":"Nice and simple for exercise 2."},{"Start":"04:24.545 ","End":"04:30.240","Text":"I\u0027ll see you in the next one where we work with another pair of variables. See you then."}],"ID":27335},{"Watched":false,"Name":"Exercise 3","Duration":"9m 44s","ChapterTopicVideoID":26434,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.580","Text":"Hello, welcome back again."},{"Start":"00:02.580 ","End":"00:04.890","Text":"In this exercise, we\u0027ve been asked to create"},{"Start":"00:04.890 ","End":"00:07.875","Text":"another pair of variables in the Code Pad once again,"},{"Start":"00:07.875 ","End":"00:13.455","Text":"this time to create a char variable and assign it the value a,"},{"Start":"00:13.455 ","End":"00:17.775","Text":"then to create a short variable with no initial value."},{"Start":"00:17.775 ","End":"00:20.580","Text":"Then in part c, we\u0027ve been asked to assign the contents of"},{"Start":"00:20.580 ","End":"00:25.620","Text":"the char variable to the short variable and explain what happens."},{"Start":"00:25.620 ","End":"00:30.405","Text":"In part d we\u0027re asked to do part c again,"},{"Start":"00:30.405 ","End":"00:34.770","Text":"but in front of the char variable name put the following characters exactly"},{"Start":"00:34.770 ","End":"00:39.240","Text":"as they appear so (short)."},{"Start":"00:39.240 ","End":"00:41.990","Text":"In part e, we\u0027re asked to look at the contents of"},{"Start":"00:41.990 ","End":"00:47.275","Text":"the short variable and explain why it contains the particular value that it contains."},{"Start":"00:47.275 ","End":"00:49.370","Text":"Moving on into part f,"},{"Start":"00:49.370 ","End":"00:51.110","Text":"we move on to Unicode characters."},{"Start":"00:51.110 ","End":"00:55.380","Text":"We\u0027re asked to assign a Unicode character \u0027\\u9000\u0027,"},{"Start":"00:56.650 ","End":"00:59.180","Text":"to the char variable."},{"Start":"00:59.180 ","End":"01:01.430","Text":"Then in part g, once again,"},{"Start":"01:01.430 ","End":"01:04.130","Text":"to assign the value of that char variable to"},{"Start":"01:04.130 ","End":"01:09.875","Text":"the short variable with short in brackets in front of the char variable name."},{"Start":"01:09.875 ","End":"01:14.690","Text":"Then in the final part to look at the contents of the short variable again, and again,"},{"Start":"01:14.690 ","End":"01:19.805","Text":"explain why it contains the particular value it contains and what has gone wrong."},{"Start":"01:19.805 ","End":"01:26.690","Text":"We first have been asked to create a char variable and assign it with the value a."},{"Start":"01:26.690 ","End":"01:28.490","Text":"Let\u0027s go ahead and do that."},{"Start":"01:28.490 ","End":"01:31.370","Text":"We haven\u0027t been told a identifier,"},{"Start":"01:31.370 ","End":"01:33.800","Text":"so I\u0027m going to call mine my char,"},{"Start":"01:33.800 ","End":"01:38.830","Text":"not particularly descriptive, but it\u0027ll do for purposes of this exercise."},{"Start":"01:38.830 ","End":"01:41.870","Text":"Note that when you\u0027re assigning a char value,"},{"Start":"01:41.870 ","End":"01:43.714","Text":"it\u0027s a single quote,"},{"Start":"01:43.714 ","End":"01:46.730","Text":"and it\u0027s closed with a single quote as well,"},{"Start":"01:46.730 ","End":"01:49.655","Text":"not speech marks, which is double-quotes,"},{"Start":"01:49.655 ","End":"01:52.220","Text":"which would be shifted to on most keyboards."},{"Start":"01:52.220 ","End":"01:56.180","Text":"It\u0027s just a single quote that\u0027s needed for a char. There we go."},{"Start":"01:56.180 ","End":"02:01.880","Text":"I\u0027ve defined my variable and it has a value just to check that value and sure enough,"},{"Start":"02:01.880 ","End":"02:05.795","Text":"it\u0027s a data type of char and it contains the value a."},{"Start":"02:05.795 ","End":"02:07.130","Text":"Then in the second part,"},{"Start":"02:07.130 ","End":"02:10.460","Text":"we\u0027ve been asked to create a short variable with no initial value."},{"Start":"02:10.460 ","End":"02:14.130","Text":"Fair enough, call it my short,"},{"Start":"02:14.130 ","End":"02:18.290","Text":"I\u0027ll be consistent and no initial value,"},{"Start":"02:18.290 ","End":"02:22.265","Text":"so I\u0027ll just end it with a semicolon just to prove It will"},{"Start":"02:22.265 ","End":"02:31.550","Text":"have an initial value and it\u0027s initialized to 0 by default by the Java system."},{"Start":"02:31.550 ","End":"02:34.880","Text":"That\u0027s fine. Now I\u0027m asked to assign"},{"Start":"02:34.880 ","End":"02:39.410","Text":"the contents of the char variable to the short variable."},{"Start":"02:39.410 ","End":"02:44.495","Text":"Assign the contents of the my char variable to the my short variables."},{"Start":"02:44.495 ","End":"02:50.720","Text":"My short comes first because it\u0027s the thing that I want to receive the value into,"},{"Start":"02:50.720 ","End":"02:55.970","Text":"and my char is on the right-hand side of the assignment operator."},{"Start":"02:55.970 ","End":"02:58.280","Text":"Let\u0027s see what happens if I try that."},{"Start":"02:58.280 ","End":"03:00.965","Text":"Unsurprisingly hopefully to you,"},{"Start":"03:00.965 ","End":"03:04.790","Text":"I get an error message and it says, incompatible types."},{"Start":"03:04.790 ","End":"03:07.414","Text":"However, what\u0027s interesting about this error message."},{"Start":"03:07.414 ","End":"03:12.710","Text":"It doesn\u0027t seem to be a closed book and it looks very similar to"},{"Start":"03:12.710 ","End":"03:15.890","Text":"some similar messages we had before when we were dealing with"},{"Start":"03:15.890 ","End":"03:19.450","Text":"floats and different sizes of integer and so on."},{"Start":"03:19.450 ","End":"03:24.670","Text":"It almost seems that it\u0027s possible to do this but we\u0027re not quite"},{"Start":"03:24.670 ","End":"03:26.680","Text":"going about it the right way because it\u0027s saying"},{"Start":"03:26.680 ","End":"03:30.175","Text":"possible lossy conversion from char to short."},{"Start":"03:30.175 ","End":"03:33.430","Text":"We will see that in the next part,"},{"Start":"03:33.430 ","End":"03:34.840","Text":"in part d,"},{"Start":"03:34.840 ","End":"03:38.350","Text":"where I\u0027ve been asked to take exactly what I had before,"},{"Start":"03:38.350 ","End":"03:48.435","Text":"but put the following characters (short) in front of my char and see what happens."},{"Start":"03:48.435 ","End":"03:55.545","Text":"Strangely, the error message goes away and I\u0027m reflected back the value 97."},{"Start":"03:55.545 ","End":"03:59.770","Text":"What we\u0027re seeing here is something called casting or it\u0027s also called"},{"Start":"03:59.770 ","End":"04:04.370","Text":"coercion where we\u0027re saying to the system,"},{"Start":"04:04.370 ","End":"04:11.025","Text":"I know that one of these things is a short data type and one is a char data type"},{"Start":"04:11.025 ","End":"04:14.420","Text":"and normally you cannot assign a variable"},{"Start":"04:14.420 ","End":"04:17.810","Text":"of one data type to a different data type but just,"},{"Start":"04:17.810 ","End":"04:25.160","Text":"for now, I\u0027d like you to pretend essentially that my Char is not a char, it\u0027s a short."},{"Start":"04:25.160 ","End":"04:28.250","Text":"If it can do it, the system will actually go ahead and try and"},{"Start":"04:28.250 ","End":"04:31.340","Text":"do it and this will work in C and other languages as well."},{"Start":"04:31.340 ","End":"04:34.625","Text":"What we\u0027ve done here is we\u0027ve cast my char,"},{"Start":"04:34.625 ","End":"04:36.650","Text":"which is a char into a short,"},{"Start":"04:36.650 ","End":"04:40.385","Text":"and then we\u0027ve been able to assign it into my short."},{"Start":"04:40.385 ","End":"04:43.325","Text":"The value 97 we\u0027re being asked,"},{"Start":"04:43.325 ","End":"04:46.940","Text":"why does it contain this value in part e?"},{"Start":"04:46.940 ","End":"04:54.770","Text":"We might be able to guess that the letter a actually has a value in the ASCII table,"},{"Start":"04:54.770 ","End":"04:58.295","Text":"and it happens to be a is 97."},{"Start":"04:58.295 ","End":"05:01.445","Text":"What has happened here is the system has said, all right,"},{"Start":"05:01.445 ","End":"05:05.330","Text":"I know this is a char and my char is not changed,"},{"Start":"05:05.330 ","End":"05:06.830","Text":"by the way, if I look at my chart,"},{"Start":"05:06.830 ","End":"05:13.400","Text":"it still contains a character a but my short now contains not 0 but 97,"},{"Start":"05:13.400 ","End":"05:19.385","Text":"which happens to be the ASCII value of the character that\u0027s stored in my chart."},{"Start":"05:19.385 ","End":"05:23.090","Text":"This statement here has basically said, \"Yes,"},{"Start":"05:23.090 ","End":"05:26.825","Text":"I know you can assign a char to a short,"},{"Start":"05:26.825 ","End":"05:33.350","Text":"but can you just pretend the char is a short and store it into my short variable\"."},{"Start":"05:33.350 ","End":"05:35.225","Text":"It has done, and it\u0027s worked."},{"Start":"05:35.225 ","End":"05:38.195","Text":"That could be useful in some situations."},{"Start":"05:38.195 ","End":"05:40.460","Text":"It does allow you to do it,"},{"Start":"05:40.460 ","End":"05:44.810","Text":"but there could be some issues and we\u0027ll see that in the subsequent parts."},{"Start":"05:44.810 ","End":"05:47.425","Text":"If we look at Part f,"},{"Start":"05:47.425 ","End":"05:50.105","Text":"it asks us to assign a Unicode character,"},{"Start":"05:50.105 ","End":"05:53.675","Text":"\\u9000 to a char variable. Let\u0027s go ahead and do that."},{"Start":"05:53.675 ","End":"05:58.910","Text":"The variable is called my char and we put a single quote, backslash,"},{"Start":"05:58.910 ","End":"06:06.720","Text":"not a forward slash u and then 9,000 has to be 4 digits, hexadecimal digits."},{"Start":"06:06.720 ","End":"06:11.870","Text":"There we go. Assign the value and I get a symbol from"},{"Start":"06:11.870 ","End":"06:17.600","Text":"the Unicode character space that is a symbol in the Chinese alphabet."},{"Start":"06:17.600 ","End":"06:19.895","Text":"We wouldn\u0027t call it an alphabet, I guess it\u0027s a symbol."},{"Start":"06:19.895 ","End":"06:21.440","Text":"There are thousands of symbols,"},{"Start":"06:21.440 ","End":"06:26.464","Text":"which is why they\u0027re so high up in the Chinese symbols range,"},{"Start":"06:26.464 ","End":"06:28.340","Text":"and we call this symbol C, J, K by the way,"},{"Start":"06:28.340 ","End":"06:32.420","Text":"because Japanese and Korean also fall into the same range."},{"Start":"06:32.420 ","End":"06:37.125","Text":"There\u0027s a C, J, K symbol in my char now,"},{"Start":"06:37.125 ","End":"06:40.790","Text":"and correct me now I can do stuff with that, I can display it,"},{"Start":"06:40.790 ","End":"06:44.750","Text":"or I can search for it because it\u0027s in a variable now in a char variable."},{"Start":"06:44.750 ","End":"06:52.395","Text":"But let\u0027s try and do what we did before and assign this value into my short."},{"Start":"06:52.395 ","End":"06:54.830","Text":"My char now has a different value in it,"},{"Start":"06:54.830 ","End":"07:01.355","Text":"which is that character represented by the Unicode value 9,000 hex."},{"Start":"07:01.355 ","End":"07:04.640","Text":"Let\u0027s try and do what we did before and we know it worked before I got"},{"Start":"07:04.640 ","End":"07:09.710","Text":"97 into my short when I had the letter a in there."},{"Start":"07:09.710 ","End":"07:11.665","Text":"Let\u0027s see what happens now."},{"Start":"07:11.665 ","End":"07:16.265","Text":"I get a negative number, very strange."},{"Start":"07:16.265 ","End":"07:20.210","Text":"Now, why would I have got a negative number?"},{"Start":"07:20.210 ","End":"07:25.415","Text":"Why does short contain that value I\u0027m being asked in part h?"},{"Start":"07:25.415 ","End":"07:29.000","Text":"Well the reason is the size of short,"},{"Start":"07:29.000 ","End":"07:32.540","Text":"short remember is a 16-bit number,"},{"Start":"07:32.540 ","End":"07:35.705","Text":"but it\u0027s a signed 16-bit number so actually,"},{"Start":"07:35.705 ","End":"07:39.965","Text":"the maximum value you can have is a 15-bit number,"},{"Start":"07:39.965 ","End":"07:42.710","Text":"which is 3, 2, 7, 6, 7."},{"Start":"07:42.710 ","End":"07:47.390","Text":"It just so happens that 9,000 hex is a bigger number than 3,"},{"Start":"07:47.390 ","End":"07:52.025","Text":"2, 7, 6, 7, it\u0027s actually 36,864."},{"Start":"07:52.025 ","End":"07:56.225","Text":"What\u0027s happening here is I\u0027m going outside the range that can"},{"Start":"07:56.225 ","End":"08:00.740","Text":"be displayed in 15 bits or can be encoded in 15 bits."},{"Start":"08:00.740 ","End":"08:04.130","Text":"It\u0027s wrapped around through a negative value."},{"Start":"08:04.130 ","End":"08:10.760","Text":"I think really all this illustrates is although we can sometimes convert"},{"Start":"08:10.760 ","End":"08:14.420","Text":"one data type into another temporarily for the purposes"},{"Start":"08:14.420 ","End":"08:18.170","Text":"of an assignment by using this costing syntax,"},{"Start":"08:18.170 ","End":"08:22.075","Text":"which is to put a data type in brackets ahead of your variable name,"},{"Start":"08:22.075 ","End":"08:25.520","Text":"it can sometimes have unexpected effects"},{"Start":"08:25.520 ","End":"08:28.910","Text":"so you\u0027ve got to be very careful if you\u0027re doing this."},{"Start":"08:28.910 ","End":"08:30.829","Text":"If you\u0027re using, for example,"},{"Start":"08:30.829 ","End":"08:33.740","Text":"7-bit ASCII characters, no problem,"},{"Start":"08:33.740 ","End":"08:37.280","Text":"you can convert an integer that is values from 0 to"},{"Start":"08:37.280 ","End":"08:41.690","Text":"127 into an ASCII value from 0 to 127."},{"Start":"08:41.690 ","End":"08:44.900","Text":"No problem. But if it\u0027s anything else,"},{"Start":"08:44.900 ","End":"08:46.805","Text":"you\u0027ve got to be very careful."},{"Start":"08:46.805 ","End":"08:52.505","Text":"This short might, on the surface seem okay because it\u0027s 16 bits and so is Unicode,"},{"Start":"08:52.505 ","End":"08:59.810","Text":"but actually the short is 15 bits in the positive direction and negative direction,"},{"Start":"08:59.810 ","End":"09:02.075","Text":"and one bit is used for the sign so"},{"Start":"09:02.075 ","End":"09:06.210","Text":"it\u0027s potentially an area where you can have a problem."},{"Start":"09:06.210 ","End":"09:10.010","Text":"This exercise has shown you that you can\u0027t"},{"Start":"09:10.010 ","End":"09:16.145","Text":"normally put a variable of one data type into another variable of a different data type"},{"Start":"09:16.145 ","End":"09:21.560","Text":"but you can coerce one variable to temporarily pretend it\u0027s"},{"Start":"09:21.560 ","End":"09:24.560","Text":"a different type but that may or may not"},{"Start":"09:24.560 ","End":"09:27.825","Text":"cause problems and it\u0027s just something to be aware of."},{"Start":"09:27.825 ","End":"09:32.120","Text":"Generally, remember that data types are there to enforce"},{"Start":"09:32.120 ","End":"09:37.700","Text":"some constraints on the variable so they\u0027re there for a reason and it can be overwritten,"},{"Start":"09:37.700 ","End":"09:40.670","Text":"but just need to be very careful if you\u0027re going to do that."},{"Start":"09:40.670 ","End":"09:42.500","Text":"That\u0027s it for this exercise."},{"Start":"09:42.500 ","End":"09:44.970","Text":"I\u0027ll see for the next one."}],"ID":27336},{"Watched":false,"Name":"Exercise 4","Duration":"6m 39s","ChapterTopicVideoID":26427,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.415","Text":"Hello. Welcome back to the next video on the exercises on assignments and expressions."},{"Start":"00:05.415 ","End":"00:09.450","Text":"Here we\u0027ve been asked to create a 3rd integer variable in Code Pad called"},{"Start":"00:09.450 ","End":"00:14.910","Text":"num3 to complement the 2 integer variables we created in an earlier exercise."},{"Start":"00:14.910 ","End":"00:19.200","Text":"In part a, we\u0027ve been asked to assign the value 10 to num1,"},{"Start":"00:19.200 ","End":"00:21.120","Text":"20 to num2,"},{"Start":"00:21.120 ","End":"00:23.055","Text":"and 4 to num3,"},{"Start":"00:23.055 ","End":"00:26.250","Text":"and then check the contents of all 3 of those variables."},{"Start":"00:26.250 ","End":"00:31.980","Text":"In part b, we\u0027ve been asked to create a single expression involving all 3 of"},{"Start":"00:31.980 ","End":"00:38.210","Text":"those variables that adds num1 to num2 divided by num3,"},{"Start":"00:38.210 ","End":"00:41.830","Text":"and then note results of that evaluation."},{"Start":"00:41.830 ","End":"00:45.410","Text":"In part c, we\u0027ve been asked to take that same expression,"},{"Start":"00:45.410 ","End":"00:48.470","Text":"but put brackets around the addition of num1 and"},{"Start":"00:48.470 ","End":"00:52.495","Text":"num2 and then explain the resulting evaluation."},{"Start":"00:52.495 ","End":"00:54.325","Text":"Then finally, in part d,"},{"Start":"00:54.325 ","End":"00:59.270","Text":"I\u0027ve been asked to use the same expression again as part c,"},{"Start":"00:59.270 ","End":"01:02.660","Text":"but to use the modulo operation this time instead of"},{"Start":"01:02.660 ","End":"01:06.950","Text":"the divide operation and to explain the resulting evaluation."},{"Start":"01:06.950 ","End":"01:13.070","Text":"In question 4, we\u0027ve been asked to create a 3rd integer variable in co bad num3."},{"Start":"01:13.070 ","End":"01:16.250","Text":"We already created num1 and 2 in exercise 2."},{"Start":"01:16.250 ","End":"01:19.145","Text":"I\u0027ve actually got rid of mine because I\u0027ve started a new session."},{"Start":"01:19.145 ","End":"01:22.130","Text":"But you only need to put all of these in."},{"Start":"01:22.130 ","End":"01:24.800","Text":"I\u0027m going to create all 3 variables again."},{"Start":"01:24.800 ","End":"01:28.505","Text":"As I said, if you already still have num1 and num2,"},{"Start":"01:28.505 ","End":"01:30.304","Text":"you just need to create num3."},{"Start":"01:30.304 ","End":"01:36.430","Text":"Now, I have my 3 variables and part a asks me to assign the value 10 to num1,"},{"Start":"01:36.430 ","End":"01:38.980","Text":"20 to num2,"},{"Start":"01:39.170 ","End":"01:42.300","Text":"and 4 to num3."},{"Start":"01:42.300 ","End":"01:46.565","Text":"In part b, it now ask me to create a single expression involving"},{"Start":"01:46.565 ","End":"01:51.795","Text":"all 3 variables that adds num1 to num2 divided by num3."},{"Start":"01:51.795 ","End":"01:55.310","Text":"I haven\u0027t been told to store those values anywhere."},{"Start":"01:55.310 ","End":"01:59.660","Text":"I\u0027ve simply been asked to create an expression involving those 3 variables."},{"Start":"01:59.660 ","End":"02:01.580","Text":"That sounds straightforward enough."},{"Start":"02:01.580 ","End":"02:10.065","Text":"Num1 gets added to num2 divided by num3."},{"Start":"02:10.065 ","End":"02:12.825","Text":"It will evaluate to 15."},{"Start":"02:12.825 ","End":"02:14.305","Text":"Then part c,"},{"Start":"02:14.305 ","End":"02:18.260","Text":"I have been asked to put brackets around the addition of num1 and"},{"Start":"02:18.260 ","End":"02:23.240","Text":"2 and explain the evaluation that results from that."},{"Start":"02:23.240 ","End":"02:27.230","Text":"I\u0027ll just do our power to get back what I\u0027ve just typed."},{"Start":"02:27.230 ","End":"02:28.820","Text":"I\u0027ll do as I\u0027ve been asked,"},{"Start":"02:28.820 ","End":"02:36.015","Text":"which is to put brackets around num1 plus num2 and the value I get is 7."},{"Start":"02:36.015 ","End":"02:40.550","Text":"How can I explain the difference between those 2 evaluations?"},{"Start":"02:40.550 ","End":"02:42.350","Text":"Well, the first one here,"},{"Start":"02:42.350 ","End":"02:46.010","Text":"as we know the order of precedence comes in here."},{"Start":"02:46.010 ","End":"02:49.415","Text":"Normally we\u0027d evaluate from left to right, however,"},{"Start":"02:49.415 ","End":"02:55.415","Text":"some operations have a greater precedence than others and division and multiplication"},{"Start":"02:55.415 ","End":"03:02.089","Text":"would be an example of something that has a higher precedence than plus and minus."},{"Start":"03:02.089 ","End":"03:04.655","Text":"The division will happen first."},{"Start":"03:04.655 ","End":"03:11.045","Text":"Therefore, num2 will be divided by num3 and the result of that will be added to num1."},{"Start":"03:11.045 ","End":"03:12.950","Text":"That\u0027s exactly what we saw."},{"Start":"03:12.950 ","End":"03:18.485","Text":"Num2 was 20, num3 was 4."},{"Start":"03:18.485 ","End":"03:22.455","Text":"So 20 was divided by 4,"},{"Start":"03:22.455 ","End":"03:24.615","Text":"which will give us 5, of course,"},{"Start":"03:24.615 ","End":"03:28.235","Text":"and then it was added to num1 because num1 had 10 in it,"},{"Start":"03:28.235 ","End":"03:32.045","Text":"the result was 15 as we would expect."},{"Start":"03:32.045 ","End":"03:37.700","Text":"The result of putting brackets around num1 and num2,"},{"Start":"03:37.700 ","End":"03:40.750","Text":"brackets have the highest order of precedence of all."},{"Start":"03:40.750 ","End":"03:43.415","Text":"So they will be evaluated first,"},{"Start":"03:43.415 ","End":"03:44.750","Text":"and then the division,"},{"Start":"03:44.750 ","End":"03:47.015","Text":"although it has a higher precedence, now,"},{"Start":"03:47.015 ","End":"03:49.550","Text":"will be overridden by the brackets."},{"Start":"03:49.550 ","End":"03:52.010","Text":"It has a higher precedence than plus that is to say,"},{"Start":"03:52.010 ","End":"03:56.390","Text":"as it did here, the brackets now will be evaluated first."},{"Start":"03:56.390 ","End":"03:59.395","Text":"Num1 will be added to num2."},{"Start":"03:59.395 ","End":"04:05.455","Text":"Therefore, we\u0027d have 30 and then 30 is divided by num3, which is 4."},{"Start":"04:05.455 ","End":"04:07.120","Text":"Now, why do we get 7?"},{"Start":"04:07.120 ","End":"04:13.180","Text":"Because 30 divided by 4 is 28 with a remainder and"},{"Start":"04:13.180 ","End":"04:15.820","Text":"we only ask to give the integer part"},{"Start":"04:15.820 ","End":"04:19.404","Text":"because all these variables involved are integer variables."},{"Start":"04:19.404 ","End":"04:22.630","Text":"Therefore, the result of the expression would also be an integer,"},{"Start":"04:22.630 ","End":"04:26.140","Text":"and it\u0027s evaluated to the value 7."},{"Start":"04:26.140 ","End":"04:28.690","Text":"In part d, we\u0027ve been asked to use"},{"Start":"04:28.690 ","End":"04:32.095","Text":"exactly the same expression as part c, which was this one,"},{"Start":"04:32.095 ","End":"04:37.894","Text":"but to change the divide operator to the percent operator,"},{"Start":"04:37.894 ","End":"04:42.800","Text":"which means modulo and to explain the results of the evaluation."},{"Start":"04:42.800 ","End":"04:44.450","Text":"Now, we get 2."},{"Start":"04:44.450 ","End":"04:46.622","Text":"Going through those numbers again,"},{"Start":"04:46.622 ","End":"04:50.330","Text":"what we\u0027re seeing is num1 plus num2,"},{"Start":"04:50.330 ","End":"04:54.760","Text":"as we said, was 30 divided by 4."},{"Start":"04:54.760 ","End":"04:58.070","Text":"We are asked to give the remainder when we divide by 4."},{"Start":"04:58.070 ","End":"05:00.545","Text":"Not the quotient, but the remainder."},{"Start":"05:00.545 ","End":"05:03.870","Text":"The remainder when we divide 30 by 4,"},{"Start":"05:03.870 ","End":"05:08.645","Text":"we get 28 and then the remainder of 2,"},{"Start":"05:08.645 ","End":"05:11.165","Text":"so the result is 2."},{"Start":"05:11.165 ","End":"05:15.980","Text":"It\u0027s showing really the difference between the division and the modulo operators,"},{"Start":"05:15.980 ","End":"05:17.315","Text":"they\u0027re obviously related,"},{"Start":"05:17.315 ","End":"05:19.790","Text":"and how that applies to integers."},{"Start":"05:19.790 ","End":"05:25.125","Text":"We also saw how precedence is affected by brackets."},{"Start":"05:25.125 ","End":"05:28.730","Text":"This was a very straightforward expression involving"},{"Start":"05:28.730 ","End":"05:32.239","Text":"just a couple of numbers, 3 different variables."},{"Start":"05:32.239 ","End":"05:35.660","Text":"In fact, we can have a play around with this till our heart is"},{"Start":"05:35.660 ","End":"05:39.170","Text":"content by just typing in values and seeing how they\u0027re evaluated."},{"Start":"05:39.170 ","End":"05:41.660","Text":"These were variables, but if we wanted to,"},{"Start":"05:41.660 ","End":"05:46.940","Text":"we could put literals in here if we wanted to see what the effect would"},{"Start":"05:46.940 ","End":"05:53.855","Text":"be and how a set of brackets could be used to affect the order evaluation."},{"Start":"05:53.855 ","End":"05:56.750","Text":"You might be able to predict what you\u0027d get from this value."},{"Start":"05:56.750 ","End":"06:01.834","Text":"For example, what we\u0027ve got is 12 times 3 is going to happen first,"},{"Start":"06:01.834 ","End":"06:05.160","Text":"and that would give us 36."},{"Start":"06:05.160 ","End":"06:08.190","Text":"Then we minus 3 plus 4,"},{"Start":"06:08.190 ","End":"06:09.475","Text":"which is 7,"},{"Start":"06:09.475 ","End":"06:11.378","Text":"and that, obviously, gives us 29."},{"Start":"06:11.378 ","End":"06:12.950","Text":"Have a play around with this."},{"Start":"06:12.950 ","End":"06:16.730","Text":"The expressions can involve a variable or they can involve literals,"},{"Start":"06:16.730 ","End":"06:20.345","Text":"but they eventually will be evaluated and return a value."},{"Start":"06:20.345 ","End":"06:23.240","Text":"Of course that value could be stored into a variable."},{"Start":"06:23.240 ","End":"06:24.770","Text":"We haven\u0027t done that here."},{"Start":"06:24.770 ","End":"06:29.735","Text":"We weren\u0027t asked to, but it\u0027s probably going to happen in a real program."},{"Start":"06:29.735 ","End":"06:34.220","Text":"That\u0027s it for very simple expressions using some of"},{"Start":"06:34.220 ","End":"06:39.990","Text":"the mathematical operators and we\u0027re done for question 4."}],"ID":27337},{"Watched":false,"Name":"Exercise 5","Duration":"12m 57s","ChapterTopicVideoID":26428,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.220","Text":"Hello, welcome back. In this exercise,"},{"Start":"00:02.220 ","End":"00:05.280","Text":"we\u0027ve been asked to use the same variables as in the previous exercise,"},{"Start":"00:05.280 ","End":"00:08.085","Text":"integer variables from num1 to num3."},{"Start":"00:08.085 ","End":"00:10.830","Text":"In part a, we\u0027ve been asked to assign the value 7"},{"Start":"00:10.830 ","End":"00:13.980","Text":"to variable num1 and 8 to variable num2."},{"Start":"00:13.980 ","End":"00:18.000","Text":"Then in part b, which has got some sub-questions we\u0027ve been asked,"},{"Start":"00:18.000 ","End":"00:20.040","Text":"without using any other variables,"},{"Start":"00:20.040 ","End":"00:22.980","Text":"to use the comparison or relational operators."},{"Start":"00:22.980 ","End":"00:26.820","Text":"As they are also known in the Code Pad to test first of all,"},{"Start":"00:26.820 ","End":"00:29.115","Text":"if num1 and num2 are equal."},{"Start":"00:29.115 ","End":"00:30.810","Text":"Then in part 2,"},{"Start":"00:30.810 ","End":"00:34.245","Text":"if num1 and num2 are not equal,"},{"Start":"00:34.245 ","End":"00:39.000","Text":"in part b iii is num1 greater than num2,"},{"Start":"00:39.000 ","End":"00:43.589","Text":"and in part b iv is num1 less than num2."},{"Start":"00:43.589 ","End":"00:49.310","Text":"Then in part c, we\u0027ve been asked to change the value of num2 to 7 and then retest to"},{"Start":"00:49.310 ","End":"00:55.100","Text":"see if in part c1 num1 is greater than or equal to num2."},{"Start":"00:55.100 ","End":"01:00.145","Text":"In part c2, if num1 is less than or equal to num2."},{"Start":"01:00.145 ","End":"01:02.360","Text":"In the next part of the exercise,"},{"Start":"01:02.360 ","End":"01:04.325","Text":"we use the logical operators."},{"Start":"01:04.325 ","End":"01:09.360","Text":"Part d asks us to assign the value 9 to num3."},{"Start":"01:09.360 ","End":"01:14.180","Text":"Then we use the logical and operator to create a single expression that"},{"Start":"01:14.180 ","End":"01:20.305","Text":"evaluates whether num2 is greater than 5 and less than 10."},{"Start":"01:20.305 ","End":"01:23.905","Text":"In part f, we\u0027re asked to change the value of num2 to 5,"},{"Start":"01:23.905 ","End":"01:27.775","Text":"then run the expression above again, in part g,"},{"Start":"01:27.775 ","End":"01:33.530","Text":"we\u0027re asked to use the logical or operator instead to create a single expression that"},{"Start":"01:33.530 ","End":"01:40.585","Text":"evaluates whether num1 is less than num2 or num3 is equal to 11."},{"Start":"01:40.585 ","End":"01:41.870","Text":"In part h,"},{"Start":"01:41.870 ","End":"01:45.440","Text":"we\u0027re asked to change the value of num3 to 11 and run"},{"Start":"01:45.440 ","End":"01:50.125","Text":"the expression from part f again to see if the evaluation changes."},{"Start":"01:50.125 ","End":"01:55.550","Text":"Then finally, we\u0027re asked to create our own expression using a combination of"},{"Start":"01:55.550 ","End":"01:59.030","Text":"logical and comparison operators and to include"},{"Start":"01:59.030 ","End":"02:02.890","Text":"the not operator and brackets to change the order of evaluation."},{"Start":"02:02.890 ","End":"02:05.210","Text":"We\u0027re asked to change the value of at least one of"},{"Start":"02:05.210 ","End":"02:09.635","Text":"our variables and to see the effect on the evaluation."},{"Start":"02:09.635 ","End":"02:12.440","Text":"In this exercise number 5,"},{"Start":"02:12.440 ","End":"02:16.340","Text":"we\u0027ve been asked to use the same variables as in Exercise 4."},{"Start":"02:16.340 ","End":"02:20.075","Text":"We add num1 to num3 or integer variables,"},{"Start":"02:20.075 ","End":"02:24.455","Text":"and to perform various steps in the code patterns before."},{"Start":"02:24.455 ","End":"02:28.820","Text":"The first step in part a is to assign num1,"},{"Start":"02:28.820 ","End":"02:30.495","Text":"the value 7,"},{"Start":"02:30.495 ","End":"02:34.080","Text":"and num2, the value 8."},{"Start":"02:34.080 ","End":"02:35.835","Text":"Let\u0027s go ahead and do that."},{"Start":"02:35.835 ","End":"02:37.960","Text":"Then in part b,"},{"Start":"02:37.960 ","End":"02:42.230","Text":"we\u0027re being asked to not use any other variables but to use the comparison,"},{"Start":"02:42.230 ","End":"02:46.220","Text":"also known as relational operators in Code Pad to test"},{"Start":"02:46.220 ","End":"02:52.340","Text":"various logical tests using comparison operators."},{"Start":"02:52.340 ","End":"02:54.980","Text":"The first one b part 1,"},{"Start":"02:54.980 ","End":"02:59.830","Text":"is asking to see if num1 and num2 are equal."},{"Start":"02:59.830 ","End":"03:05.000","Text":"First trap you could follow in here is to use a single equal sign."},{"Start":"03:05.000 ","End":"03:09.230","Text":"Remember the single equal sign means, assign a value."},{"Start":"03:09.230 ","End":"03:14.465","Text":"Double equals sign is the comparison operator in Java."},{"Start":"03:14.465 ","End":"03:17.465","Text":"We\u0027re comparing one value to another."},{"Start":"03:17.465 ","End":"03:19.465","Text":"In this expression we\u0027re saying,"},{"Start":"03:19.465 ","End":"03:21.905","Text":"is num1 equal to num2?"},{"Start":"03:21.905 ","End":"03:27.200","Text":"Does it contain the same value as num2? Let\u0027s see if it does."},{"Start":"03:27.200 ","End":"03:31.220","Text":"I get a response which is a Boolean response."},{"Start":"03:31.220 ","End":"03:35.330","Text":"These operators all return a Boolean response."},{"Start":"03:35.330 ","End":"03:37.160","Text":"In this case, it\u0027s false."},{"Start":"03:37.160 ","End":"03:39.635","Text":"Because num1 contains 7,"},{"Start":"03:39.635 ","End":"03:41.355","Text":"as you\u0027ve seen here,"},{"Start":"03:41.355 ","End":"03:42.990","Text":"and num2 contains 8."},{"Start":"03:42.990 ","End":"03:44.625","Text":"Clearly, they\u0027re not the same."},{"Start":"03:44.625 ","End":"03:49.145","Text":"We would expect therefore the evaluation to return false."},{"Start":"03:49.145 ","End":"03:53.540","Text":"In b2, we\u0027re asked to see if num1 and num2 are not"},{"Start":"03:53.540 ","End":"03:58.175","Text":"equal and just to test that we remember what the operator is."},{"Start":"03:58.175 ","End":"04:01.670","Text":"It is the not sign,"},{"Start":"04:01.670 ","End":"04:05.899","Text":"which is an exclamation mark followed by equals, no spaces."},{"Start":"04:05.899 ","End":"04:10.160","Text":"We\u0027re saying it\u0027s not equal to num2."},{"Start":"04:10.160 ","End":"04:13.985","Text":"As we know, 7 and 8 are not equal."},{"Start":"04:13.985 ","End":"04:18.590","Text":"The expression here generates a result of true,"},{"Start":"04:18.590 ","End":"04:25.670","Text":"num1 not equal to num2 returns the evaluation of true."},{"Start":"04:25.670 ","End":"04:32.224","Text":"In b3, we\u0027re asked to see if num1 is greater than num2."},{"Start":"04:32.224 ","End":"04:36.890","Text":"This is simple case of remembering your greater than and less than symbols."},{"Start":"04:36.890 ","End":"04:40.085","Text":"Num1 is greater than num2."},{"Start":"04:40.085 ","End":"04:41.870","Text":"We know that that\u0027s not true,"},{"Start":"04:41.870 ","End":"04:46.040","Text":"so we expect a false because 7 is not greater than 8."},{"Start":"04:46.040 ","End":"04:48.185","Text":"Let\u0027s try it the other way round then,"},{"Start":"04:48.185 ","End":"04:50.600","Text":"which is b4,"},{"Start":"04:50.600 ","End":"04:53.630","Text":"num1 is less than num2."},{"Start":"04:53.630 ","End":"04:56.030","Text":"Here\u0027s the less than operator."},{"Start":"04:56.030 ","End":"05:00.770","Text":"We would expect that to be true because 7 is less than 8."},{"Start":"05:00.770 ","End":"05:03.080","Text":"We are given a value true,"},{"Start":"05:03.080 ","End":"05:05.075","Text":"which is just what we\u0027d expect."},{"Start":"05:05.075 ","End":"05:12.180","Text":"We\u0027ve used the basic operators now in terms of comparison or relational operators."},{"Start":"05:12.180 ","End":"05:15.000","Text":"They will operate, as you would expect."},{"Start":"05:15.000 ","End":"05:18.695","Text":"Something\u0027s either equal to something else or it\u0027s not equal to something else."},{"Start":"05:18.695 ","End":"05:22.475","Text":"It\u0027s greater than something else or it\u0027s less than something else."},{"Start":"05:22.475 ","End":"05:27.365","Text":"We\u0027re now in part c. We\u0027ve asked to change the value of num2 to 7."},{"Start":"05:27.365 ","End":"05:28.850","Text":"Let\u0027s go ahead and do that."},{"Start":"05:28.850 ","End":"05:32.970","Text":"Remember, num1 is also 7 and then in"},{"Start":"05:32.970 ","End":"05:37.655","Text":"c1 we\u0027ve been asked to test if num1 is greater than or equal to num2."},{"Start":"05:37.655 ","End":"05:43.160","Text":"This is really just so that we get the idea of the greater than or equal to operator,"},{"Start":"05:43.160 ","End":"05:44.780","Text":"which is 2 symbols."},{"Start":"05:44.780 ","End":"05:49.129","Text":"The greater than comes first and the equals comes second."},{"Start":"05:49.129 ","End":"05:55.040","Text":"We\u0027re saying is num1 either greater than or exactly equal to num2."},{"Start":"05:55.040 ","End":"06:00.275","Text":"Of course, it is exactly equal to num2."},{"Start":"06:00.275 ","End":"06:04.785","Text":"Remember before, num1 greater than num2 return to false."},{"Start":"06:04.785 ","End":"06:07.730","Text":"This time because we\u0027ve changed it to greater than or"},{"Start":"06:07.730 ","End":"06:10.955","Text":"equal to and we\u0027ve changed the value of num2 to 7."},{"Start":"06:10.955 ","End":"06:16.009","Text":"We\u0027re getting a true instead of false."},{"Start":"06:16.009 ","End":"06:19.190","Text":"Let\u0027s try it the other way round or not the other way around."},{"Start":"06:19.190 ","End":"06:22.520","Text":"But let\u0027s try the less than or equal to operator,"},{"Start":"06:22.520 ","End":"06:25.055","Text":"which is part c2."},{"Start":"06:25.055 ","End":"06:34.610","Text":"We would expect that also to return true and it does because num1 is not less than num2."},{"Start":"06:34.610 ","End":"06:38.180","Text":"But it is exactly equal to num2 for the same reasons as we said above."},{"Start":"06:38.180 ","End":"06:44.150","Text":"Great. We\u0027ve used all of the basic operators for comparison and relationships."},{"Start":"06:44.150 ","End":"06:51.485","Text":"That\u0027s all straightforward and we\u0027ll see there\u0027s an awful lot in the next topic."},{"Start":"06:51.485 ","End":"06:55.190","Text":"It\u0027s really important that you\u0027ve understood this and by all means,"},{"Start":"06:55.190 ","End":"06:57.710","Text":"spend a little bit of extra time working"},{"Start":"06:57.710 ","End":"07:02.225","Text":"through some of your own examples to just drum that home."},{"Start":"07:02.225 ","End":"07:07.370","Text":"Now, part d, we\u0027ve been asked to assign the value 9 to num3."},{"Start":"07:07.370 ","End":"07:09.430","Text":"Let\u0027s go ahead and do that."},{"Start":"07:09.430 ","End":"07:14.450","Text":"Then use the logical and operator to create a single expression that"},{"Start":"07:14.450 ","End":"07:19.730","Text":"evaluates whether num2 is greater than 5 and less than 10."},{"Start":"07:19.730 ","End":"07:23.720","Text":"You\u0027ll remember that and requires two things to"},{"Start":"07:23.720 ","End":"07:27.920","Text":"be true in order to generate a true result."},{"Start":"07:27.920 ","End":"07:33.290","Text":"What we\u0027ve been asked to do here is num2 greater than 5 and less than 10?"},{"Start":"07:33.290 ","End":"07:34.760","Text":"We\u0027re going to ask two questions."},{"Start":"07:34.760 ","End":"07:38.010","Text":"We\u0027re going to say num2 greater than 5,"},{"Start":"07:38.010 ","End":"07:39.890","Text":"and we\u0027re going to ask another question,"},{"Start":"07:39.890 ","End":"07:44.905","Text":"num2 less than 10."},{"Start":"07:44.905 ","End":"07:48.605","Text":"But what we\u0027re going to do is we have to join those with an and,"},{"Start":"07:48.605 ","End":"07:50.330","Text":"and the keyword is not and."},{"Start":"07:50.330 ","End":"07:53.345","Text":"It would be in Python and Java and C,"},{"Start":"07:53.345 ","End":"07:55.070","Text":"it\u0027s a double ampersand,"},{"Start":"07:55.070 ","End":"07:59.150","Text":"2 ampersands would be a logical and."},{"Start":"07:59.150 ","End":"08:07.110","Text":"As we know, num2 contains 7."},{"Start":"08:07.110 ","End":"08:14.075","Text":"We would expect therefore because num2 is greater than 5 and num2 is less than 10."},{"Start":"08:14.075 ","End":"08:17.150","Text":"Both of those things are true either side of the logical and."},{"Start":"08:17.150 ","End":"08:19.970","Text":"We would expect the result to be true as well."},{"Start":"08:19.970 ","End":"08:24.310","Text":"We do indeed get a value of true."},{"Start":"08:24.310 ","End":"08:26.560","Text":"Now in part f,"},{"Start":"08:26.560 ","End":"08:32.135","Text":"we\u0027ve been asked to change the value of num2 to 5 and run that expression again."},{"Start":"08:32.135 ","End":"08:34.220","Text":"Let\u0027s do that."},{"Start":"08:34.220 ","End":"08:38.300","Text":"num2 equals 5. Let\u0027s run the expression again."},{"Start":"08:38.300 ","End":"08:40.490","Text":"Now this time we get a false."},{"Start":"08:40.490 ","End":"08:42.780","Text":"Exactly the same expression, but we get a false."},{"Start":"08:42.780 ","End":"08:44.750","Text":"I hope you\u0027ll realize why."},{"Start":"08:44.750 ","End":"08:49.340","Text":"It\u0027s because it\u0027s exactly equal to 5 but not greater than 5."},{"Start":"08:49.340 ","End":"08:54.395","Text":"Now num2, this part of the expression would evaluate to false."},{"Start":"08:54.395 ","End":"08:59.105","Text":"This one will be true because 5 is less than 10 still."},{"Start":"08:59.105 ","End":"09:01.670","Text":"But both parts have to be true for"},{"Start":"09:01.670 ","End":"09:05.975","Text":"the overall evaluation to come out true because that\u0027s what and expects."},{"Start":"09:05.975 ","End":"09:10.330","Text":"Hence we\u0027ve got this result of false."},{"Start":"09:10.330 ","End":"09:12.525","Text":"In part g,"},{"Start":"09:12.525 ","End":"09:15.395","Text":"we\u0027ve been asked to use the logical or operator"},{"Start":"09:15.395 ","End":"09:17.870","Text":"to create a single expression that evaluates"},{"Start":"09:17.870 ","End":"09:24.375","Text":"whether num1 is less than num2 or number 3 is equal to 11."},{"Start":"09:24.375 ","End":"09:32.255","Text":"What we want to do here then is say num1 is less than num2."},{"Start":"09:32.255 ","End":"09:37.710","Text":"Then we want the or and we say num3 equals 11."},{"Start":"09:37.710 ","End":"09:42.425","Text":"Now, or in Python is just or but in Java,"},{"Start":"09:42.425 ","End":"09:45.125","Text":"it\u0027s what we call the pipe character and it\u0027s two of them."},{"Start":"09:45.125 ","End":"09:46.850","Text":"It\u0027s like a vertical bar,"},{"Start":"09:46.850 ","End":"09:50.825","Text":"but we need two of those to do a logical or."},{"Start":"09:50.825 ","End":"09:54.680","Text":"What this is doing is it\u0027s joining two expressions together"},{"Start":"09:54.680 ","End":"09:58.730","Text":"and either of them can be true to generate a result of true."},{"Start":"09:58.730 ","End":"10:05.270","Text":"Either num1 is less than num2 or num3 is exactly equal to,"},{"Start":"10:05.270 ","End":"10:08.225","Text":"not 1, I\u0027ve been asked to do 11."},{"Start":"10:08.225 ","End":"10:12.875","Text":"Num3 is exactly equal to 11. Let\u0027s run that."},{"Start":"10:12.875 ","End":"10:20.120","Text":"I get a false because num1 is not less than num2."},{"Start":"10:20.120 ","End":"10:23.585","Text":"If we just remind ourselves what num1 has is 7."},{"Start":"10:23.585 ","End":"10:26.760","Text":"Num2 is 5."},{"Start":"10:26.760 ","End":"10:30.005","Text":"Num1 is actually greater than num2."},{"Start":"10:30.005 ","End":"10:32.374","Text":"Hence this part, it\u0027s going to be false."},{"Start":"10:32.374 ","End":"10:35.410","Text":"Num3 is not 11."},{"Start":"10:35.410 ","End":"10:39.005","Text":"Remind ourselves what num3 contains. It\u0027s got 9."},{"Start":"10:39.005 ","End":"10:41.720","Text":"Neither parts of this expression are true."},{"Start":"10:41.720 ","End":"10:43.550","Text":"That\u0027s false and that\u0027s false."},{"Start":"10:43.550 ","End":"10:47.555","Text":"Therefore, it cannot generate a true value, it generates false."},{"Start":"10:47.555 ","End":"10:50.300","Text":"However, now, if I change the values,"},{"Start":"10:50.300 ","End":"10:56.765","Text":"I\u0027ve been asked in part h of num3 to 11 and run that expression again,"},{"Start":"10:56.765 ","End":"10:59.255","Text":"what I see is true."},{"Start":"10:59.255 ","End":"11:02.330","Text":"Because even though num1 is not"},{"Start":"11:02.330 ","End":"11:05.679","Text":"less than num2 still because we didn\u0027t change their values,"},{"Start":"11:05.679 ","End":"11:08.195","Text":"7 is still not less than 5."},{"Start":"11:08.195 ","End":"11:13.790","Text":"This next part of the expression is num3 equal to 11 is now true."},{"Start":"11:13.790 ","End":"11:17.300","Text":"Only one part of this expression needs to be true with"},{"Start":"11:17.300 ","End":"11:22.175","Text":"all to generate a true as the output."},{"Start":"11:22.175 ","End":"11:26.085","Text":"That\u0027s great, that\u0027s part h done."},{"Start":"11:26.085 ","End":"11:29.510","Text":"In part i, we\u0027ve just been asked to use any combination of"},{"Start":"11:29.510 ","End":"11:32.360","Text":"logical and comparison operators and maybe use"},{"Start":"11:32.360 ","End":"11:36.950","Text":"the not operator as well and brackets to change the order of evaluation."},{"Start":"11:36.950 ","End":"11:38.435","Text":"Do have a play around with that."},{"Start":"11:38.435 ","End":"11:41.030","Text":"I\u0027ll show you an example of what I mean."},{"Start":"11:41.030 ","End":"11:45.825","Text":"For example, I could put a not around the whole thing."},{"Start":"11:45.825 ","End":"11:47.595","Text":"Brackets, first of all,"},{"Start":"11:47.595 ","End":"11:49.680","Text":"all of this will be evaluated."},{"Start":"11:49.680 ","End":"11:51.485","Text":"Whatever the result is."},{"Start":"11:51.485 ","End":"11:54.800","Text":"I will flip the results to the opposite."},{"Start":"11:54.800 ","End":"11:57.065","Text":"You see I was getting true before."},{"Start":"11:57.065 ","End":"11:59.735","Text":"It should flip back to false and it has."},{"Start":"11:59.735 ","End":"12:02.615","Text":"By taking the not out again,"},{"Start":"12:02.615 ","End":"12:04.760","Text":"you\u0027ll see it goes back to true."},{"Start":"12:04.760 ","End":"12:12.045","Text":"Note, the logical not operation just flips the output to the opposite Boolean value."},{"Start":"12:12.045 ","End":"12:13.670","Text":"The brackets, as you see,"},{"Start":"12:13.670 ","End":"12:15.545","Text":"it\u0027s evaluating this whole thing."},{"Start":"12:15.545 ","End":"12:18.335","Text":"Here is one. You can use that in any way you want."},{"Start":"12:18.335 ","End":"12:21.200","Text":"I can have another set of brackets inside the brackets if I wanted to,"},{"Start":"12:21.200 ","End":"12:23.690","Text":"it wouldn\u0027t make any difference in this particular example."},{"Start":"12:23.690 ","End":"12:28.205","Text":"But do have a play around with that and see the effect of brackets"},{"Start":"12:28.205 ","End":"12:33.350","Text":"on the way that things will be evaluated in a logical comparison."},{"Start":"12:33.350 ","End":"12:35.270","Text":"That\u0027s great. In these questions,"},{"Start":"12:35.270 ","End":"12:37.850","Text":"we\u0027ve looked at the logical operators,"},{"Start":"12:37.850 ","End":"12:40.350","Text":"the basic ones were and and or,"},{"Start":"12:40.350 ","End":"12:42.860","Text":"and then we also have not and we also looked at"},{"Start":"12:42.860 ","End":"12:46.475","Text":"the comparison and relational operators of equal to,"},{"Start":"12:46.475 ","End":"12:49.340","Text":"not equal to, greater than, less than,"},{"Start":"12:49.340 ","End":"12:53.690","Text":"and then greater than or equals to and less than or equal to."},{"Start":"12:53.690 ","End":"12:57.600","Text":"I\u0027ll see you in the next exercise."}],"ID":27338},{"Watched":false,"Name":"Exercise 6","Duration":"10m 22s","ChapterTopicVideoID":26429,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.770","Text":"Welcome. In this exercise we\u0027re going to explore the bitwise operators."},{"Start":"00:04.770 ","End":"00:06.540","Text":"In the code pad, as usual,"},{"Start":"00:06.540 ","End":"00:12.465","Text":"we\u0027re going to create a variable using the byte datatype and assign it the value 65."},{"Start":"00:12.465 ","End":"00:13.890","Text":"Then n part b,"},{"Start":"00:13.890 ","End":"00:17.895","Text":"we\u0027re going to perform a bitwise and operation on the variable."},{"Start":"00:17.895 ","End":"00:21.675","Text":"We\u0027re going to use this binary value to do that bitwise."},{"Start":"00:21.675 ","End":"00:26.690","Text":"In part c, we\u0027re asked to explain why you get the resulting value."},{"Start":"00:26.690 ","End":"00:32.525","Text":"In part d, we\u0027re asked to perform a bitwise or operation on the variable,"},{"Start":"00:32.525 ","End":"00:35.990","Text":"but this time using the decimal value 32."},{"Start":"00:35.990 ","End":"00:39.590","Text":"Then again to explain why we get this new value."},{"Start":"00:39.590 ","End":"00:43.970","Text":"In part f, we assign the value 17 to the byte variable,"},{"Start":"00:43.970 ","End":"00:47.450","Text":"then perform a bitwise exclusive or"},{"Start":"00:47.450 ","End":"00:51.920","Text":"operation on the variable using this binary value here."},{"Start":"00:51.920 ","End":"00:55.490","Text":"Once again, we\u0027re asked to explain the resulting evaluation."},{"Start":"00:55.490 ","End":"01:00.065","Text":"Then finally, we assign the value 1 to the byte variable,"},{"Start":"01:00.065 ","End":"01:03.950","Text":"and then perform a complement operation on the variable,"},{"Start":"01:03.950 ","End":"01:08.840","Text":"and we\u0027re asked to explain the value that we get and we\u0027re given a little hint."},{"Start":"01:08.840 ","End":"01:16.730","Text":"We\u0027ll start by creating the variable as he\u0027s asked us in part a. Typing the datatype,"},{"Start":"01:16.730 ","End":"01:18.500","Text":"give it a name,"},{"Start":"01:18.500 ","End":"01:24.340","Text":"and then assign the value 65 as it\u0027s asks us to complete that with a semicolon."},{"Start":"01:24.340 ","End":"01:28.070","Text":"Now in part b, we\u0027ve been asked to perform a bitwise and"},{"Start":"01:28.070 ","End":"01:32.225","Text":"operation on the variable using the given value."},{"Start":"01:32.225 ","End":"01:39.710","Text":"A variable name comes first the bitwise and operation is a single ampersand symbol."},{"Start":"01:39.710 ","End":"01:44.430","Text":"The value we\u0027ve been asked to and width is 0b01000000."},{"Start":"01:46.850 ","End":"01:49.715","Text":"Lets go and see what that does."},{"Start":"01:49.715 ","End":"01:53.135","Text":"The value we get back is 64."},{"Start":"01:53.135 ","End":"01:56.510","Text":"As we know with an and we have to have a"},{"Start":"01:56.510 ","End":"02:01.909","Text":"1 in both bytes in order to get a 1 at the output."},{"Start":"02:01.909 ","End":"02:04.640","Text":"Maybe it\u0027s easier to see this if we have two literals."},{"Start":"02:04.640 ","End":"02:10.745","Text":"If I put 0b01000000 as we\u0027ve started with,"},{"Start":"02:10.745 ","End":"02:15.770","Text":"and the value that we\u0027re ending with is 65,"},{"Start":"02:15.770 ","End":"02:19.255","Text":"which is actually a same bit pattern,"},{"Start":"02:19.255 ","End":"02:21.500","Text":"but with a 1 at the end."},{"Start":"02:21.500 ","End":"02:23.150","Text":"If we add those together,"},{"Start":"02:23.150 ","End":"02:26.570","Text":"we should get the same results, and we do."},{"Start":"02:26.570 ","End":"02:31.250","Text":"It\u0027s much easier to see obviously with the binary representation because"},{"Start":"02:31.250 ","End":"02:36.730","Text":"65 here has a 1 and 64 only has a 1."},{"Start":"02:36.730 ","End":"02:39.470","Text":"Therefore, the output is also going to be"},{"Start":"02:39.470 ","End":"02:42.730","Text":"64 because the only places where there are 2 1s,"},{"Start":"02:42.730 ","End":"02:45.465","Text":"are these 2 bit positions here."},{"Start":"02:45.465 ","End":"02:49.550","Text":"That explains and the value we get from parts a and b,"},{"Start":"02:49.550 ","End":"02:51.545","Text":"so part c is done."},{"Start":"02:51.545 ","End":"02:54.260","Text":"Now we are asked to perform a bitwise or"},{"Start":"02:54.260 ","End":"02:57.470","Text":"operation on the same variable with the same content Susan,"},{"Start":"02:57.470 ","End":"02:59.455","Text":"the decimal value 32."},{"Start":"02:59.455 ","End":"03:03.280","Text":"This just involves us using again a variable name,"},{"Start":"03:03.280 ","End":"03:09.395","Text":"and this time the bitwise or operation is the vertical bar or pipe character,"},{"Start":"03:09.395 ","End":"03:11.120","Text":"and only one of those is needed."},{"Start":"03:11.120 ","End":"03:13.385","Text":"A logical order would have two of them"},{"Start":"03:13.385 ","End":"03:16.930","Text":"because this is a bit wise or we only need one of them."},{"Start":"03:16.930 ","End":"03:19.850","Text":"Then we\u0027ve been asked to use the value 32."},{"Start":"03:19.850 ","End":"03:22.475","Text":"What\u0027s the value we get back?"},{"Start":"03:22.475 ","End":"03:25.760","Text":"We get 97 this time."},{"Start":"03:25.760 ","End":"03:31.940","Text":"Let\u0027s try and explain that value is it\u0027s asked us to in part e. Well,"},{"Start":"03:31.940 ","End":"03:34.700","Text":"if we do the same thing again and go from"},{"Start":"03:34.700 ","End":"03:38.345","Text":"the binary versions and the binary representations."},{"Start":"03:38.345 ","End":"03:43.460","Text":"We know already that 65 is 0b01000001"},{"Start":"03:43.460 ","End":"03:50.590","Text":", so that\u0027s 65."},{"Start":"03:50.590 ","End":"03:56.090","Text":"If we do a bit wise or with 32 is represented"},{"Start":"03:56.090 ","End":"04:01.545","Text":"by 0b00100000,or the first bit there will be 1 to 8,"},{"Start":"04:01.545 ","End":"04:04.995","Text":"then 64, then 32 there."},{"Start":"04:04.995 ","End":"04:08.685","Text":"Then all the other 4 bits will be 0s."},{"Start":"04:08.685 ","End":"04:12.570","Text":"Let\u0027s see what we get there and we do indeed get 97."},{"Start":"04:12.570 ","End":"04:16.865","Text":"We can see again more clearly when we do it with binary values"},{"Start":"04:16.865 ","End":"04:22.025","Text":"that the bitwise or will take each individual bit and,"},{"Start":"04:22.025 ","End":"04:26.010","Text":"or a bit in the respective position."},{"Start":"04:26.110 ","End":"04:31.715","Text":"Here, because we\u0027ve got an extra bit being set here,"},{"Start":"04:31.715 ","End":"04:35.410","Text":"the result will also have an extra bit set."},{"Start":"04:35.410 ","End":"04:37.115","Text":"It will be set here,"},{"Start":"04:37.115 ","End":"04:43.730","Text":"and the result. We\u0027ll have 01100001."},{"Start":"04:43.730 ","End":"04:49.805","Text":"If we want to prove that to send a look at the value of 97 in binary"},{"Start":"04:49.805 ","End":"04:58.590","Text":"should be 01100001 if we\u0027ve assumed,"},{"Start":"04:58.590 ","End":"04:59.910","Text":"right and it is."},{"Start":"04:59.910 ","End":"05:01.800","Text":"You can see that very clearly,"},{"Start":"05:01.800 ","End":"05:03.260","Text":"got a 1 set there,"},{"Start":"05:03.260 ","End":"05:05.540","Text":"but we\u0027ve also got at 1 set there,"},{"Start":"05:05.540 ","End":"05:08.195","Text":"which is what we see appearing here."},{"Start":"05:08.195 ","End":"05:13.520","Text":"The rest of it is all 0s apart from this bit here, which has a1."},{"Start":"05:13.520 ","End":"05:20.224","Text":"That explains part e. Moving on to part f,"},{"Start":"05:20.224 ","End":"05:23.675","Text":"we assign the value 17 to the variables."},{"Start":"05:23.675 ","End":"05:25.580","Text":"Let\u0027s go ahead and do that."},{"Start":"05:25.580 ","End":"05:28.280","Text":"Now we\u0027ve got 17 decimal in there."},{"Start":"05:28.280 ","End":"05:32.375","Text":"Now we\u0027ve been asked to perform a bitwise exclusive or"},{"Start":"05:32.375 ","End":"05:37.040","Text":"operation on that variable using a given binary value."},{"Start":"05:37.040 ","End":"05:42.425","Text":"Bitwise exclusive or we don\u0027t see a logical equivalent,"},{"Start":"05:42.425 ","End":"05:46.745","Text":"but that\u0027s the symbol for the operator to do a bitwise exclusive"},{"Start":"05:46.745 ","End":"05:51.230","Text":"or remember exclusive or means, not both bits."},{"Start":"05:51.230 ","End":"05:58.190","Text":"If 2 bits are set to operate in the 2 data items that were exclusive oriented together,"},{"Start":"05:58.190 ","End":"06:04.655","Text":"we ignore that bit once only one of them to have a 1 at the output."},{"Start":"06:04.655 ","End":"06:09.450","Text":"The value had been asked to put in 0b00010001."},{"Start":"06:12.670 ","End":"06:16.860","Text":"Let us see what result we get,"},{"Start":"06:16.860 ","End":"06:19.730","Text":"and 0 shortly, There we go."},{"Start":"06:19.730 ","End":"06:22.805","Text":"The result I get is 0."},{"Start":"06:22.805 ","End":"06:25.550","Text":"Now why do I get 0?"},{"Start":"06:25.550 ","End":"06:27.710","Text":"Well, the reason is,"},{"Start":"06:27.710 ","End":"06:31.025","Text":"if we were to put this again in binary,"},{"Start":"06:31.025 ","End":"06:35.435","Text":"actually what we\u0027ll find is the binary value that we were"},{"Start":"06:35.435 ","End":"06:40.655","Text":"oring with exclusive or in width is actually 17."},{"Start":"06:40.655 ","End":"06:46.010","Text":"We were doing 17 and exclusive oring with 17."},{"Start":"06:46.010 ","End":"06:54.229","Text":"Because both of these patterns have 1s in exactly the same place and nowhere else,"},{"Start":"06:54.229 ","End":"06:59.440","Text":"the result is going to be 0 and hopefully you can see that."},{"Start":"06:59.440 ","End":"07:04.700","Text":"Let\u0027s just prove that we\u0027ve got a 1 in this position and in"},{"Start":"07:04.700 ","End":"07:06.830","Text":"this position and we\u0027ve got a 1 in this position and"},{"Start":"07:06.830 ","End":"07:09.290","Text":"that position of course we have because they have the same number,"},{"Start":"07:09.290 ","End":"07:13.055","Text":"although we didn\u0027t make that obvious by putting it in decimal initially."},{"Start":"07:13.055 ","End":"07:18.440","Text":"The reason the output is 0 is because there is nowhere in either of these"},{"Start":"07:18.440 ","End":"07:23.810","Text":"2 where there is a 1 and it isn\u0027t already present in the other side."},{"Start":"07:23.810 ","End":"07:29.915","Text":"Hence, we get the result of 0 and that\u0027s why exclusive or is doing its job."},{"Start":"07:29.915 ","End":"07:32.359","Text":"It\u0027s only putting a 1 at the output."},{"Start":"07:32.359 ","End":"07:37.050","Text":"If the relative position doesn\u0027t have 2 1s."},{"Start":"07:37.050 ","End":"07:38.445","Text":"If there\u0027s a single 1,"},{"Start":"07:38.445 ","End":"07:40.245","Text":"then the output will have a 1."},{"Start":"07:40.245 ","End":"07:41.600","Text":"There\u0027s 2 0s,"},{"Start":"07:41.600 ","End":"07:43.535","Text":"then obviously it will have a 0 there."},{"Start":"07:43.535 ","End":"07:45.875","Text":"Let\u0027s do the last part,"},{"Start":"07:45.875 ","End":"07:53.535","Text":"which is part h. We\u0027ve been told to assign the value 1 to the variable,"},{"Start":"07:53.535 ","End":"07:56.075","Text":"and then to perform a complement."},{"Start":"07:56.075 ","End":"07:58.880","Text":"A complement operator is different than the one\u0027s we\u0027ve"},{"Start":"07:58.880 ","End":"08:01.805","Text":"just been using because it\u0027s what\u0027s called a unitary operator,"},{"Start":"08:01.805 ","End":"08:05.435","Text":"only needs 1 thing to operate on."},{"Start":"08:05.435 ","End":"08:09.650","Text":"The symbol itself is a tilde character."},{"Start":"08:09.650 ","End":"08:12.320","Text":"It\u0027s quite tricky to find on keyboards often,"},{"Start":"08:12.320 ","End":"08:16.250","Text":"minds next to the Enter key above the hash."},{"Start":"08:16.250 ","End":"08:18.035","Text":"It could be anywhere on your keyboard,"},{"Start":"08:18.035 ","End":"08:22.445","Text":"but it\u0027s usually in a fairly hard to find positions is not typed very often."},{"Start":"08:22.445 ","End":"08:26.540","Text":"That\u0027s the tilde character and that\u0027s what does the complement."},{"Start":"08:26.540 ","End":"08:29.300","Text":"We simply put the name of our variable and we\u0027ll"},{"Start":"08:29.300 ","End":"08:32.510","Text":"get a compliment of the value that\u0027s in the variable."},{"Start":"08:32.510 ","End":"08:34.265","Text":"I get -2,"},{"Start":"08:34.265 ","End":"08:36.575","Text":"now note I get int back."},{"Start":"08:36.575 ","End":"08:39.965","Text":"I really should be looking to get a bite back."},{"Start":"08:39.965 ","End":"08:42.920","Text":"I could do cast on this to see the result."},{"Start":"08:42.920 ","End":"08:46.880","Text":"But let\u0027s have a look at why it\u0027s -2. first of all,"},{"Start":"08:46.880 ","End":"08:49.940","Text":"because it\u0027s a signed number."},{"Start":"08:49.940 ","End":"08:53.930","Text":"If I were to do this as a byte literal,"},{"Start":"08:53.930 ","End":"08:59.610","Text":"I\u0027d get 1 is obviously all 0s in the upper level and"},{"Start":"08:59.610 ","End":"09:06.005","Text":"then 0001 that is 1 in binary."},{"Start":"09:06.005 ","End":"09:08.345","Text":"Now if I was to do a complement,"},{"Start":"09:08.345 ","End":"09:14.270","Text":"remember the complement turns every single bit to the opposite of what it currently is."},{"Start":"09:14.270 ","End":"09:21.895","Text":"All of these would be a 1 and this would be a 0."},{"Start":"09:21.895 ","End":"09:24.620","Text":"That\u0027s what the complement operation is doing."},{"Start":"09:24.620 ","End":"09:27.155","Text":"If you look at that again,"},{"Start":"09:27.155 ","End":"09:35.700","Text":"and if I actually type this out and flip it manually, 11111110."},{"Start":"09:35.810 ","End":"09:40.280","Text":"This is what the complemented version of that would look like."},{"Start":"09:40.280 ","End":"09:41.890","Text":"What\u0027s the value I get?"},{"Start":"09:41.890 ","End":"09:48.095","Text":"It\u0027s -2,and the only reason I\u0027m having to bite in front of it is when I put literals in,"},{"Start":"09:48.095 ","End":"09:51.020","Text":"in blue jay, it will assume they\u0027re integers always."},{"Start":"09:51.020 ","End":"09:53.990","Text":"A sign bit will be way over here"},{"Start":"09:53.990 ","End":"09:57.800","Text":"somewhere because it\u0027s a 32-bit number, obviously an integer."},{"Start":"09:57.800 ","End":"10:05.105","Text":"That\u0027s the explanation for part h. We get -2 because we\u0027ve complemented this pattern"},{"Start":"10:05.105 ","End":"10:08.750","Text":"when we\u0027re complimenting a bite that contains 1"},{"Start":"10:08.750 ","End":"10:12.455","Text":"and the complement will return this value here,"},{"Start":"10:12.455 ","End":"10:15.250","Text":"which I\u0027ve typed out as binary search easier for you to see,"},{"Start":"10:15.250 ","End":"10:16.880","Text":"and that binary value,"},{"Start":"10:16.880 ","End":"10:19.925","Text":"if it\u0027s a byte, is worth -2."},{"Start":"10:19.925 ","End":"10:23.580","Text":"That\u0027s it for this one. I\u0027ll see you in the next one."}],"ID":27339},{"Watched":false,"Name":"Exercise 7","Duration":"9m 3s","ChapterTopicVideoID":26430,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.910","Text":"Hi, again. In this video we\u0027re going to look at"},{"Start":"00:02.910 ","End":"00:05.550","Text":"the exercise in which we explore the increment,"},{"Start":"00:05.550 ","End":"00:08.880","Text":"decrement, and compound assignment operators."},{"Start":"00:08.880 ","End":"00:12.630","Text":"We have first been asked to create a variable of int datatype,"},{"Start":"00:12.630 ","End":"00:15.810","Text":"and to assign to it the initial value 10 decimal."},{"Start":"00:15.810 ","End":"00:20.070","Text":"In part a then, we\u0027re asked to use the post increment operator"},{"Start":"00:20.070 ","End":"00:23.910","Text":"on the variable and to not put a semicolon on the end of the line."},{"Start":"00:23.910 ","End":"00:26.160","Text":"In part b, we\u0027re asked the question,"},{"Start":"00:26.160 ","End":"00:31.290","Text":"why does that value reflected back by Bluej not appear to change?"},{"Start":"00:31.290 ","End":"00:33.450","Text":"Then we use in Part C,"},{"Start":"00:33.450 ","End":"00:36.615","Text":"the pre increment operator on the same variable."},{"Start":"00:36.615 ","End":"00:40.770","Text":"Once again, not to put a semicolon on the end of the line."},{"Start":"00:40.770 ","End":"00:42.500","Text":"In Part d,"},{"Start":"00:42.500 ","End":"00:47.990","Text":"we\u0027re asked what difference we observe between post and pre increment."},{"Start":"00:47.990 ","End":"00:50.330","Text":"Moving on to part e,"},{"Start":"00:50.330 ","End":"00:55.575","Text":"we are using now the pre decrement operator on the variable."},{"Start":"00:55.575 ","End":"01:00.110","Text":"In part f, we use the post decrement operator on the variable."},{"Start":"01:00.110 ","End":"01:03.980","Text":"Then, we use a compound assignment to multiply the variable"},{"Start":"01:03.980 ","End":"01:08.355","Text":"by 10 and store the result back into the variable."},{"Start":"01:08.355 ","End":"01:11.630","Text":"In part h, we use another compound assignment to"},{"Start":"01:11.630 ","End":"01:15.175","Text":"add 28 to the variable and store the result back in."},{"Start":"01:15.175 ","End":"01:17.260","Text":"Finally in part i,"},{"Start":"01:17.260 ","End":"01:25.150","Text":"we\u0027re asked to use a compound assignment to do a bitwise exclusive or with a value 129."},{"Start":"01:25.150 ","End":"01:30.875","Text":"We\u0027ve been first starts to create a variable of int datatype."},{"Start":"01:30.875 ","End":"01:33.870","Text":"Let\u0027s go ahead and do that."},{"Start":"01:34.460 ","End":"01:41.405","Text":"We are asked to give it the initial value of 10 in decimal."},{"Start":"01:41.405 ","End":"01:44.060","Text":"Then in part a, we\u0027re asked to use"},{"Start":"01:44.060 ","End":"01:46.320","Text":"the post increment operator on"},{"Start":"01:46.320 ","End":"01:49.505","Text":"the variable and to not put a semicolon on the end of the line."},{"Start":"01:49.505 ","End":"01:52.195","Text":"We get a value straight back."},{"Start":"01:52.195 ","End":"01:56.390","Text":"The increment and decrement operators are unitary."},{"Start":"01:56.390 ","End":"01:58.895","Text":"Once again, they only need one thing to operate on."},{"Start":"01:58.895 ","End":"02:01.160","Text":"If it\u0027s a post increment operator,"},{"Start":"02:01.160 ","End":"02:03.365","Text":"it follows the name of the variable."},{"Start":"02:03.365 ","End":"02:08.835","Text":"We\u0027ll put myVar, and then two pluses that will increment myVar by one."},{"Start":"02:08.835 ","End":"02:10.980","Text":"Let\u0027s see the value."},{"Start":"02:10.980 ","End":"02:14.205","Text":"Now, I had 10 in there originally."},{"Start":"02:14.205 ","End":"02:19.580","Text":"It does not seem to have changed as part b seems to suggest."},{"Start":"02:19.580 ","End":"02:23.400","Text":"It\u0027s asking, why it doesn\u0027t appear to change?"},{"Start":"02:23.400 ","End":"02:24.890","Text":"There is a clue there,"},{"Start":"02:24.890 ","End":"02:26.540","Text":"and it says appear to change."},{"Start":"02:26.540 ","End":"02:30.405","Text":"The value reflected back was 10."},{"Start":"02:30.405 ","End":"02:32.764","Text":"But what does myVar actually contain?"},{"Start":"02:32.764 ","End":"02:35.660","Text":"It actually contains 11."},{"Start":"02:35.660 ","End":"02:38.750","Text":"What we\u0027re seeing here is the difference between the post increment"},{"Start":"02:38.750 ","End":"02:42.215","Text":"and a pre increment when it\u0027s used in an expression."},{"Start":"02:42.215 ","End":"02:43.910","Text":"Although it doesn\u0027t look like it,"},{"Start":"02:43.910 ","End":"02:49.010","Text":"this is an expression and could be used in an expression if we wanted it to"},{"Start":"02:49.010 ","End":"02:54.950","Text":"but what it\u0027s doing is it\u0027s giving us the value back before it increments it."},{"Start":"02:54.950 ","End":"03:00.015","Text":"Hence, the name post increment because it will return a value."},{"Start":"03:00.015 ","End":"03:04.490","Text":"Then after post the return of the value, equal increment it."},{"Start":"03:04.490 ","End":"03:06.260","Text":"That\u0027s exactly what\u0027s happened here."},{"Start":"03:06.260 ","End":"03:07.595","Text":"We started with 10,"},{"Start":"03:07.595 ","End":"03:09.170","Text":"myVar had 10 in it,"},{"Start":"03:09.170 ","End":"03:11.975","Text":"and when we executed myVar plus, plus."},{"Start":"03:11.975 ","End":"03:16.325","Text":"It gave us back the value before the increment,"},{"Start":"03:16.325 ","End":"03:19.715","Text":"which we see here, but when we display the value,"},{"Start":"03:19.715 ","End":"03:23.820","Text":"we\u0027ve seen them, it\u0027s actually got 11 and then now."},{"Start":"03:23.820 ","End":"03:27.320","Text":"Let\u0027s see it should be fairly obvious what happens in part"},{"Start":"03:27.320 ","End":"03:32.030","Text":"c. Use the pre increment operator on the variable,"},{"Start":"03:32.030 ","End":"03:35.010","Text":"and don\u0027t put a semicolon on the end."},{"Start":"03:35.010 ","End":"03:36.829","Text":"We see the value back straightaway."},{"Start":"03:36.829 ","End":"03:39.170","Text":"If I do plus plus MyVar,"},{"Start":"03:39.170 ","End":"03:41.525","Text":"that\u0027s the pre increment."},{"Start":"03:41.525 ","End":"03:44.150","Text":"Increment because it\u0027s plus, double plus,"},{"Start":"03:44.150 ","End":"03:48.095","Text":"and pre because it comes before the variable name."},{"Start":"03:48.095 ","End":"03:52.850","Text":"It reflects back the value straight away in the expression."},{"Start":"03:52.850 ","End":"03:56.000","Text":"Obviously, there\u0027s no other parts to this expression here."},{"Start":"03:56.000 ","End":"04:00.250","Text":"But it\u0027s giving me the value back straightaway of the incremented value."},{"Start":"04:00.250 ","End":"04:03.845","Text":"It was 11, and it immediately gives me 12 back."},{"Start":"04:03.845 ","End":"04:07.340","Text":"It shows me the value 12,"},{"Start":"04:07.340 ","End":"04:11.495","Text":"and it\u0027s also got stored in it 12, you\u0027ll find there."},{"Start":"04:11.495 ","End":"04:17.145","Text":"You see the contrast now between the post increment and the pre increment."},{"Start":"04:17.145 ","End":"04:20.325","Text":"Basically, they both add 1 but 1,"},{"Start":"04:20.325 ","End":"04:25.130","Text":"if it\u0027s involved in expression will return the value before it\u0027s incremented."},{"Start":"04:25.130 ","End":"04:28.805","Text":"The other one will show you the increments straight away,"},{"Start":"04:28.805 ","End":"04:32.225","Text":"as we see in these examples here."},{"Start":"04:32.225 ","End":"04:40.010","Text":"That\u0027s us done from parts a to d. Now we\u0027ve been asked to use the pre decrement operator."},{"Start":"04:40.010 ","End":"04:43.560","Text":"Presumably, that is going to be straightforward,"},{"Start":"04:43.560 ","End":"04:45.165","Text":"and follow the same pattern."},{"Start":"04:45.165 ","End":"04:50.625","Text":"Pre decrement, decrement is minus minus."},{"Start":"04:50.625 ","End":"04:53.140","Text":"This is pre decrement."},{"Start":"04:53.140 ","End":"04:56.630","Text":"It\u0027s going to give me the value back straight away when I get it"},{"Start":"04:56.630 ","End":"05:00.285","Text":"reflected back because it\u0027s used in an expression here and it\u0027s 11."},{"Start":"05:00.285 ","End":"05:01.430","Text":"Which is what I expect,"},{"Start":"05:01.430 ","End":"05:04.605","Text":"and it will contain 11, which it does."},{"Start":"05:04.605 ","End":"05:08.840","Text":"Now I\u0027m asked to use the post decrement operator."},{"Start":"05:08.840 ","End":"05:14.360","Text":"With F^F, that\u0027ll be myVar minus, minus."},{"Start":"05:14.360 ","End":"05:16.760","Text":"What do you expect to happen here?"},{"Start":"05:16.760 ","End":"05:18.800","Text":"Because it\u0027s a post decrement,"},{"Start":"05:18.800 ","End":"05:22.310","Text":"we should see 11 reflected back because that\u0027s"},{"Start":"05:22.310 ","End":"05:26.600","Text":"the value that we expect before we take away 1."},{"Start":"05:26.600 ","End":"05:29.520","Text":"But it then should subsequently contain 10."},{"Start":"05:29.520 ","End":"05:32.790","Text":"We do indeed see 11 reflected back."},{"Start":"05:32.790 ","End":"05:35.040","Text":"If we look at myVar,"},{"Start":"05:35.040 ","End":"05:38.070","Text":"it does indeed contain 10."},{"Start":"05:38.070 ","End":"05:41.990","Text":"That\u0027s us done from parts a to f. Now"},{"Start":"05:41.990 ","End":"05:47.330","Text":"the last couple of parts to this exercise asks us to do some compound assignments."},{"Start":"05:47.330 ","End":"05:52.340","Text":"In part g says user compound assignment to multiply the variable by 10,"},{"Start":"05:52.340 ","End":"05:54.955","Text":"and store the result back into the variable."},{"Start":"05:54.955 ","End":"06:00.065","Text":"Well at compound assignment is a very lean syntax."},{"Start":"06:00.065 ","End":"06:03.200","Text":"What it will do is do some operation,"},{"Start":"06:03.200 ","End":"06:08.300","Text":"and store immediately back the value into the variable."},{"Start":"06:08.300 ","End":"06:14.215","Text":"What we want to do is say, myVar times equals 10."},{"Start":"06:14.215 ","End":"06:17.910","Text":"What we\u0027re saying, is multiplied by 10,"},{"Start":"06:17.910 ","End":"06:21.220","Text":"and store it back into myVar."},{"Start":"06:21.220 ","End":"06:29.470","Text":"We should see a 100 stored back into myVar if we\u0027ve got the syntax right, and we do."},{"Start":"06:29.470 ","End":"06:32.960","Text":"It\u0027s not just reflecting back the current value of myVar,"},{"Start":"06:32.960 ","End":"06:35.330","Text":"it\u0027s actually stored that in MyVar as well."},{"Start":"06:35.330 ","End":"06:37.055","Text":"Just to prove it, I\u0027ll do that."},{"Start":"06:37.055 ","End":"06:43.660","Text":"The expression results in 10 being multiplied by 10 because that\u0027s what myVar had in it,"},{"Start":"06:43.660 ","End":"06:45.590","Text":"and that\u0027s what we see reflected back here."},{"Start":"06:45.590 ","End":"06:51.650","Text":"But it also results in the assignment of a new value to myVar."},{"Start":"06:51.650 ","End":"06:54.320","Text":"We\u0027re doing two things that we\u0027re doing a multiplication,"},{"Start":"06:54.320 ","End":"06:57.635","Text":"and then we\u0027re storing it back into the original variables."},{"Start":"06:57.635 ","End":"07:01.880","Text":"The equivalent way of doing this in slightly longer syntax would"},{"Start":"07:01.880 ","End":"07:05.900","Text":"have been this myVar equals myVar times 10 would have"},{"Start":"07:05.900 ","End":"07:07.880","Text":"had exactly the same result but it\u0027s"},{"Start":"07:07.880 ","End":"07:13.985","Text":"a slightly more compact form to do it with the compound assignment."},{"Start":"07:13.985 ","End":"07:16.820","Text":"That\u0027s part g. Now it\u0027s saying use"},{"Start":"07:16.820 ","End":"07:21.035","Text":"a compound assignment to add 28 to the variable and store the results."},{"Start":"07:21.035 ","End":"07:22.760","Text":"That\u0027s exactly the same."},{"Start":"07:22.760 ","End":"07:25.655","Text":"We just obviously going to use a different symbol."},{"Start":"07:25.655 ","End":"07:27.950","Text":"A plus comes first,"},{"Start":"07:27.950 ","End":"07:31.520","Text":"then the equals, and then whatever the value is,"},{"Start":"07:31.520 ","End":"07:33.365","Text":"what we want to work with."},{"Start":"07:33.365 ","End":"07:39.080","Text":"It\u0027s added 28 to what was already in there and stored it back into myVar."},{"Start":"07:39.080 ","End":"07:43.815","Text":"Myvar contains 128, nice and easy."},{"Start":"07:43.815 ","End":"07:46.940","Text":"Then the last one is to use a compound assignment to do"},{"Start":"07:46.940 ","End":"07:50.315","Text":"a bitwise exclusive or with your variable,"},{"Start":"07:50.315 ","End":"07:51.668","Text":"and the value 1, 2,"},{"Start":"07:51.668 ","End":"07:53.880","Text":"9, install them only back."},{"Start":"07:53.880 ","End":"08:02.340","Text":"That is going to be myVar bitwise exclusive or is the current symbols,"},{"Start":"08:02.340 ","End":"08:05.734","Text":"is usually shift, and, followed by equals."},{"Start":"08:05.734 ","End":"08:06.980","Text":"We just did that on its own."},{"Start":"08:06.980 ","End":"08:11.015","Text":"It would do the bitwise exclusive or but it wouldn\u0027t store it back into myVar."},{"Start":"08:11.015 ","End":"08:15.485","Text":"We put the equals to store it back into myVar."},{"Start":"08:15.485 ","End":"08:18.432","Text":"Then we will use the value 1,"},{"Start":"08:18.432 ","End":"08:20.520","Text":"2, 9, and see what we get back."},{"Start":"08:20.520 ","End":"08:22.095","Text":"We get 1 back."},{"Start":"08:22.095 ","End":"08:25.725","Text":"Because remember the bitwise exclusive or,"},{"Start":"08:25.725 ","End":"08:29.415","Text":"doesn\u0027t want to see two 1s\u0027 in any bit position,"},{"Start":"08:29.415 ","End":"08:30.942","Text":"1, 2, 8, and 1, 2,"},{"Start":"08:30.942 ","End":"08:36.500","Text":"9 are exactly the same number with the least significant bit set in 1, 2, 9."},{"Start":"08:36.500 ","End":"08:39.845","Text":"It\u0027s the same as doing this, for example."},{"Start":"08:39.845 ","End":"08:42.105","Text":"This will be 1, 2, 8."},{"Start":"08:42.105 ","End":"08:46.220","Text":"If we do a bitwise exclusive or,"},{"Start":"08:46.220 ","End":"08:47.720","Text":"with 1, 2, 9,"},{"Start":"08:47.720 ","End":"08:50.705","Text":"it\u0027ll learn this. Hence, we get 1."},{"Start":"08:50.705 ","End":"08:54.749","Text":"Because we did an compound assignment,"},{"Start":"08:54.749 ","End":"08:56.940","Text":"that value in myVar will now be stored away."},{"Start":"08:56.940 ","End":"08:58.695","Text":"MyVar will contain 1."},{"Start":"08:58.695 ","End":"09:01.305","Text":"That\u0027s it for Exercise 7."},{"Start":"09:01.305 ","End":"09:03.940","Text":"I\u0027ll see you in the next one."}],"ID":27340},{"Watched":false,"Name":"Exercise 8","Duration":"9m 11s","ChapterTopicVideoID":26431,"CourseChapterTopicPlaylistID":246357,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.940","Text":"Hey, welcome back. In this final exercise,"},{"Start":"00:02.940 ","End":"00:05.340","Text":"we\u0027re going to move away from the code pad and"},{"Start":"00:05.340 ","End":"00:08.520","Text":"instead create a program in the BlueJ editor."},{"Start":"00:08.520 ","End":"00:12.090","Text":"We\u0027ve eventually been asked to create a class in this project that we\u0027ve already"},{"Start":"00:12.090 ","End":"00:15.480","Text":"been working in code MyTempConverterApp."},{"Start":"00:15.480 ","End":"00:19.740","Text":"Then in Part A to declare a variable of an appropriate type to hold"},{"Start":"00:19.740 ","End":"00:27.600","Text":"an input temperature and to give it an initial value of 37.77778."},{"Start":"00:27.600 ","End":"00:30.750","Text":"Then in Part B, to declare a variable of an appropriate type,"},{"Start":"00:30.750 ","End":"00:33.615","Text":"again, to hold an output temperature."},{"Start":"00:33.615 ","End":"00:38.770","Text":"Then in Part C, we\u0027re asked to create a method inside the class called Convert."},{"Start":"00:38.770 ","End":"00:41.660","Text":"Then in Part D, within the Convert method,"},{"Start":"00:41.660 ","End":"00:44.540","Text":"we are asked to add a line that uses whatever operators are"},{"Start":"00:44.540 ","End":"00:47.720","Text":"needed to convert the input temperature from"},{"Start":"00:47.720 ","End":"00:51.050","Text":"Celsius to Fahrenheit and to assign"},{"Start":"00:51.050 ","End":"00:54.855","Text":"the evaluated value to the output temperature variable."},{"Start":"00:54.855 ","End":"00:56.335","Text":"Then in Part E,"},{"Start":"00:56.335 ","End":"00:59.390","Text":"we\u0027re asked to add a second line in that method which will print"},{"Start":"00:59.390 ","End":"01:03.700","Text":"the output temperature to the screen using system out print line."},{"Start":"01:03.700 ","End":"01:06.830","Text":"Then in Part F, we are asked to compile the program and test"},{"Start":"01:06.830 ","End":"01:10.324","Text":"it correct any errors that have been signaled by the compiler."},{"Start":"01:10.324 ","End":"01:16.010","Text":"In Part G, create an object from the class to finally test the code and"},{"Start":"01:16.010 ","End":"01:22.375","Text":"run the Convert method in Part H and check that the result is a 100."},{"Start":"01:22.375 ","End":"01:28.265","Text":"The first thing we need to do is to create a class within our project."},{"Start":"01:28.265 ","End":"01:30.530","Text":"Up until now, we\u0027ve been using the codePad for everything."},{"Start":"01:30.530 ","End":"01:33.410","Text":"Generally, you would have a project which will contain"},{"Start":"01:33.410 ","End":"01:36.470","Text":"all your code and that will be made up of multiple classes,"},{"Start":"01:36.470 ","End":"01:38.720","Text":"which will appear here in this exercise."},{"Start":"01:38.720 ","End":"01:42.980","Text":"We only need 1 class and we\u0027ll do for many of the initial exercises."},{"Start":"01:42.980 ","End":"01:46.190","Text":"Let\u0027s go ahead and create the new class by clicking on the button"},{"Start":"01:46.190 ","End":"01:50.630","Text":"here and giving it the name we\u0027ve been asked to give,"},{"Start":"01:50.630 ","End":"01:58.235","Text":"which is MyTempConverterApp that we are given"},{"Start":"01:58.235 ","End":"02:02.750","Text":"the class and we will have code in which BlueJ just helpfully"},{"Start":"02:02.750 ","End":"02:07.545","Text":"puts in for you while I wanted to take it out just to make it clear what we\u0027re adding."},{"Start":"02:07.545 ","End":"02:11.405","Text":"We\u0027ll just keep the opening line and the braces."},{"Start":"02:11.405 ","End":"02:14.720","Text":"In Part A, we\u0027ve been asked to declare a variable of"},{"Start":"02:14.720 ","End":"02:19.100","Text":"an appropriate type to hold an input temperature and to give it an initial value."},{"Start":"02:19.100 ","End":"02:22.370","Text":"37 point several 7, and an 8."},{"Start":"02:22.370 ","End":"02:26.740","Text":"What would be an appropriate data type for this data?"},{"Start":"02:26.740 ","End":"02:29.255","Text":"Well, it\u0027s a real number,"},{"Start":"02:29.255 ","End":"02:31.625","Text":"so our choice is a float or a double."},{"Start":"02:31.625 ","End":"02:35.270","Text":"Double would probably be overkill for this number."},{"Start":"02:35.270 ","End":"02:37.940","Text":"There\u0027s not many digits in the decimal places,"},{"Start":"02:37.940 ","End":"02:40.560","Text":"so float will suffice."},{"Start":"02:40.560 ","End":"02:42.560","Text":"If we put the data type float,"},{"Start":"02:42.560 ","End":"02:47.225","Text":"give it a name I\u0027m going to call mine input t rather than writing out temperature."},{"Start":"02:47.225 ","End":"02:51.005","Text":"But I could write temperature or even temp perhaps would be a little bit better."},{"Start":"02:51.005 ","End":"02:52.910","Text":"Input temp for temperature."},{"Start":"02:52.910 ","End":"03:02.400","Text":"I\u0027ll give it an initial value 37.77778 and a semicolon."},{"Start":"03:02.400 ","End":"03:05.090","Text":"Then I\u0027ve been asked to declare in Part B"},{"Start":"03:05.090 ","End":"03:09.395","Text":"another variable to hold an output temperature again, of an appropriate type."},{"Start":"03:09.395 ","End":"03:11.180","Text":"Well, if the input was a float,"},{"Start":"03:11.180 ","End":"03:15.900","Text":"it would make sense for the output to be a float as well."},{"Start":"03:15.900 ","End":"03:19.415","Text":"I don\u0027t need to give it an initial value, haven\u0027t been asked to."},{"Start":"03:19.415 ","End":"03:22.280","Text":"I\u0027ll just end the line with a semicolon."},{"Start":"03:22.280 ","End":"03:23.510","Text":"We\u0027re on Part C now,"},{"Start":"03:23.510 ","End":"03:28.460","Text":"so we\u0027re asked to create a method inside the class called converts."},{"Start":"03:28.460 ","End":"03:31.085","Text":"Our method is where the code belongs."},{"Start":"03:31.085 ","End":"03:33.320","Text":"We saw when we did an initial exercise what"},{"Start":"03:33.320 ","End":"03:36.350","Text":"this looks like the structure of a Java program."},{"Start":"03:36.350 ","End":"03:39.065","Text":"Without going into too much detail,"},{"Start":"03:39.065 ","End":"03:43.625","Text":"you\u0027ll need to put in front of the name of the method a keyword void,"},{"Start":"03:43.625 ","End":"03:45.590","Text":"basically saying to the compiler,"},{"Start":"03:45.590 ","End":"03:48.350","Text":"don\u0027t expect anything to come back from this program."},{"Start":"03:48.350 ","End":"03:53.210","Text":"Then we put the name of the method and you put a pair of empty brackets for the moment."},{"Start":"03:53.210 ","End":"03:54.350","Text":"Later on in the course,"},{"Start":"03:54.350 ","End":"03:56.525","Text":"we\u0027ll find out what goes in those brackets."},{"Start":"03:56.525 ","End":"04:01.250","Text":"I\u0027ll close off my method with a closing brace here."},{"Start":"04:01.250 ","End":"04:06.380","Text":"It seems to be happy and you\u0027ll see in BlueJ highlights in yellow here,"},{"Start":"04:06.380 ","End":"04:11.275","Text":"to say that it\u0027s a method and the block is complete essentially."},{"Start":"04:11.275 ","End":"04:14.930","Text":"Code inside it should be indented it\u0027s good practice."},{"Start":"04:14.930 ","End":"04:17.120","Text":"It will still work if it doesn\u0027t but should"},{"Start":"04:17.120 ","End":"04:19.745","Text":"indent it just to make your code look a bit more readable."},{"Start":"04:19.745 ","End":"04:22.490","Text":"Now when I\u0027ve been asked to do in"},{"Start":"04:22.490 ","End":"04:27.020","Text":"Part D is to add a line that uses whatever operators are needed to"},{"Start":"04:27.020 ","End":"04:29.810","Text":"convert the imprint temperature from Celsius to"},{"Start":"04:29.810 ","End":"04:34.610","Text":"Fahrenheit and to assign the evaluated value to the output temperature value."},{"Start":"04:34.610 ","End":"04:41.300","Text":"Here I need to come up with a formula for this and we do a Google search for this."},{"Start":"04:41.300 ","End":"04:47.240","Text":"But what I\u0027m doing is I\u0027m trying to put a value into the output temp variable."},{"Start":"04:47.240 ","End":"04:50.675","Text":"That\u0027s where my expression will start output temp."},{"Start":"04:50.675 ","End":"04:52.805","Text":"Then the assignment operator,"},{"Start":"04:52.805 ","End":"04:55.700","Text":"because I want a value to go into output temp."},{"Start":"04:55.700 ","End":"04:59.960","Text":"Then the rest of the expression we\u0027ll do the calculation which calculates"},{"Start":"04:59.960 ","End":"05:07.130","Text":"a temperature in Fahrenheit when given a value in centigrade or degrees Celsius."},{"Start":"05:07.130 ","End":"05:09.050","Text":"If we have it,"},{"Start":"05:09.050 ","End":"05:12.515","Text":"the value that we want an input temp,"},{"Start":"05:12.515 ","End":"05:15.245","Text":"then that\u0027s how our expression is going to start off."},{"Start":"05:15.245 ","End":"05:19.355","Text":"If you were to look up what the conversion is,"},{"Start":"05:19.355 ","End":"05:21.710","Text":"do a web search for that."},{"Start":"05:21.710 ","End":"05:26.090","Text":"You\u0027ll find that the formula is the input temperature multiplied"},{"Start":"05:26.090 ","End":"05:31.775","Text":"by 9/5 and added to that should be 32,"},{"Start":"05:31.775 ","End":"05:33.935","Text":"and that should give you the results."},{"Start":"05:33.935 ","End":"05:37.550","Text":"Now, we won\u0027t get the correct result if we do"},{"Start":"05:37.550 ","End":"05:41.615","Text":"this and you might scratch your head and think of why wouldn\u0027t get the correct result."},{"Start":"05:41.615 ","End":"05:45.035","Text":"But actually, it comes down to this little bit here,"},{"Start":"05:45.035 ","End":"05:48.570","Text":"because this is a literal fraction"},{"Start":"05:48.570 ","End":"05:53.135","Text":"and by default what will happen is this will do an integer division."},{"Start":"05:53.135 ","End":"05:57.980","Text":"What you want to do is to force the compiler to consider this as a"},{"Start":"05:57.980 ","End":"06:03.110","Text":"fractional literal and it will work nicely."},{"Start":"06:03.110 ","End":"06:06.020","Text":"You could also work out what 9/5 is actually"},{"Start":"06:06.020 ","End":"06:10.895","Text":"1.8 and put 1.8 in there instead and that would do the job as well."},{"Start":"06:10.895 ","End":"06:12.110","Text":"If you don\u0027t do that,"},{"Start":"06:12.110 ","End":"06:16.385","Text":"you\u0027ll get an incorrect result and that will be the first little hurdle for you."},{"Start":"06:16.385 ","End":"06:21.890","Text":"Let\u0027s try and do the final part which says system out,"},{"Start":"06:21.890 ","End":"06:25.590","Text":"print line, and print the results basically."},{"Start":"06:25.590 ","End":"06:27.140","Text":"What is the result going to be?"},{"Start":"06:27.140 ","End":"06:29.975","Text":"Well, it\u0027s been stored into output temp."},{"Start":"06:29.975 ","End":"06:34.585","Text":"That is what we\u0027re looking to see."},{"Start":"06:34.585 ","End":"06:42.140","Text":"We\u0027ve done all the steps now from A to E. We probably written a few too many lines here."},{"Start":"06:42.140 ","End":"06:44.555","Text":"You should really, when you\u0027re writing a couple of lines,"},{"Start":"06:44.555 ","End":"06:47.555","Text":"test by compiling them as you\u0027re going along."},{"Start":"06:47.555 ","End":"06:49.130","Text":"If we click on compile here,"},{"Start":"06:49.130 ","End":"06:51.695","Text":"you\u0027ll see already it\u0027s found an error."},{"Start":"06:51.695 ","End":"06:55.930","Text":"Highlights in the margin here where the error is."},{"Start":"06:55.930 ","End":"06:57.350","Text":"If I click on the line,"},{"Start":"06:57.350 ","End":"07:02.539","Text":"it tells me incompatible types possible lossy conversion from double to float."},{"Start":"07:02.539 ","End":"07:04.160","Text":"What it\u0027s saying here is,"},{"Start":"07:04.160 ","End":"07:07.505","Text":"it\u0027s always assuming that if you put a fractional number,"},{"Start":"07:07.505 ","End":"07:10.820","Text":"that it\u0027s a double and it\u0027s trying to convert it from a"},{"Start":"07:10.820 ","End":"07:15.425","Text":"double to a float because it knows that that\u0027s what we want to put it into."},{"Start":"07:15.425 ","End":"07:18.020","Text":"We already saw this once before."},{"Start":"07:18.020 ","End":"07:22.820","Text":"We know that the trick here is just to put an f on the end to tell it that this"},{"Start":"07:22.820 ","End":"07:28.160","Text":"is a floating-point number and it should make the error go away."},{"Start":"07:28.160 ","End":"07:31.760","Text":"Let\u0027s compile and indeed the error does go away."},{"Start":"07:31.760 ","End":"07:35.675","Text":"We\u0027ve got a literal here which is assuming is a double."},{"Start":"07:35.675 ","End":"07:37.070","Text":"I\u0027m telling it no,"},{"Start":"07:37.070 ","End":"07:38.915","Text":"it\u0027s not double, it\u0027s a float."},{"Start":"07:38.915 ","End":"07:44.630","Text":"Therefore, I can assign it to a float without getting that warning error message."},{"Start":"07:44.630 ","End":"07:48.470","Text":"That now compiles with no syntax errors."},{"Start":"07:48.470 ","End":"07:52.715","Text":"What I\u0027m able to do now is I can close the editor."},{"Start":"07:52.715 ","End":"07:55.580","Text":"As it is asked me to do in"},{"Start":"07:55.580 ","End":"08:00.380","Text":"Part F while I\u0027ve actually compiled it and done Part F. Now I need to do Part G,"},{"Start":"08:00.380 ","End":"08:03.305","Text":"test it by creating an object from the class which you remember,"},{"Start":"08:03.305 ","End":"08:07.010","Text":"you right-click say new temperature converter app."},{"Start":"08:07.010 ","End":"08:10.340","Text":"It gives me a default name, I\u0027ll just accept."},{"Start":"08:10.340 ","End":"08:12.739","Text":"Then down here on the object workbench,"},{"Start":"08:12.739 ","End":"08:16.625","Text":"I\u0027ve got the object which I can run code on."},{"Start":"08:16.625 ","End":"08:22.940","Text":"I right-click now I select the name of the method that I wanted to run."},{"Start":"08:22.940 ","End":"08:25.130","Text":"I only have 1 method and it\u0027s called convert."},{"Start":"08:25.130 ","End":"08:31.305","Text":"I run it and it should print on the terminal the results and up pops my Terminal Window."},{"Start":"08:31.305 ","End":"08:34.385","Text":"The result is indeed what I was expecting,"},{"Start":"08:34.385 ","End":"08:36.410","Text":"which is a 100."},{"Start":"08:36.410 ","End":"08:39.290","Text":"Nice and simple program,"},{"Start":"08:39.290 ","End":"08:45.860","Text":"first useful program that we\u0027ve written really that converts a temperature from degrees"},{"Start":"08:45.860 ","End":"08:49.190","Text":"Celsius into Fahrenheit and displays the result on"},{"Start":"08:49.190 ","End":"08:53.540","Text":"the screen and only took a few lines of code to do that."},{"Start":"08:53.540 ","End":"08:56.675","Text":"But the key to it was this expression here,"},{"Start":"08:56.675 ","End":"09:04.415","Text":"which evaluated what this calculation is and then store the result into output temp,"},{"Start":"09:04.415 ","End":"09:07.400","Text":"which we then displayed on the screen."},{"Start":"09:07.400 ","End":"09:11.940","Text":"Thanks very much, and I\u0027ll see you in the next video."}],"ID":27341}],"Thumbnail":null,"ID":246357},{"Name":"Conditional Control Structures","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"If Structure","Duration":"6m 59s","ChapterTopicVideoID":26021,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.064","Text":"Hello everybody. By the end of this section on control structures,"},{"Start":"00:04.064 ","End":"00:06.690","Text":"you\u0027ll be able to explain the significance of"},{"Start":"00:06.690 ","End":"00:10.350","Text":"instructions being running sequence in imperative languages,"},{"Start":"00:10.350 ","End":"00:14.205","Text":"describe how high-level constructs allow code to be skipped,"},{"Start":"00:14.205 ","End":"00:17.925","Text":"and evaluate which control structures suit a particular problem."},{"Start":"00:17.925 ","End":"00:22.065","Text":"So far as simple programs we\u0027ve built stored values in variables,"},{"Start":"00:22.065 ","End":"00:27.255","Text":"perform mathematical operations, and output the contents of variables to the screen."},{"Start":"00:27.255 ","End":"00:30.480","Text":"In these programs, every instruction is executed by"},{"Start":"00:30.480 ","End":"00:33.750","Text":"the CPU 1 after the other in sequence."},{"Start":"00:33.750 ","End":"00:37.995","Text":"Instructions are fetched from memory and carried out one at a time."},{"Start":"00:37.995 ","End":"00:41.985","Text":"The program ends when there are no more instructions to execute."},{"Start":"00:41.985 ","End":"00:45.890","Text":"This idea of instructions running in sequence 1 after the other is"},{"Start":"00:45.890 ","End":"00:49.610","Text":"one of the fundamental building blocks of imperative programming languages."},{"Start":"00:49.610 ","End":"00:54.605","Text":"As a programmer, we write out instructions in the order we want them to be executed."},{"Start":"00:54.605 ","End":"00:58.295","Text":"Sometimes the order of 2 particular lines may not be important."},{"Start":"00:58.295 ","End":"01:00.740","Text":"At other times, a completely different outcome would"},{"Start":"01:00.740 ","End":"01:03.800","Text":"occur if 2 lines are in a different sequence."},{"Start":"01:03.800 ","End":"01:09.350","Text":"In this example, the program will output a message saying that the total is 16."},{"Start":"01:09.350 ","End":"01:11.210","Text":"If we did it another way,"},{"Start":"01:11.210 ","End":"01:14.330","Text":"swapping the order in which we add numbers to the total,"},{"Start":"01:14.330 ","End":"01:16.500","Text":"we\u0027d get exactly the same outcome,"},{"Start":"01:16.500 ","End":"01:19.595","Text":"a message saying the total is 16."},{"Start":"01:19.595 ","End":"01:24.005","Text":"In this example, we\u0027d see 21 output to the screen,"},{"Start":"01:24.005 ","End":"01:29.285","Text":"because 11 is in total by the time we get to line 3,"},{"Start":"01:29.285 ","End":"01:34.279","Text":"and then we add on 10 and the message would say the total is 21."},{"Start":"01:34.279 ","End":"01:38.675","Text":"But swapping the second and third lines over it gives us a different result."},{"Start":"01:38.675 ","End":"01:46.235","Text":"Total plus 10 will give us 10 and then we replace the contents of total with 6 plus 5."},{"Start":"01:46.235 ","End":"01:48.530","Text":"The message output will be different,"},{"Start":"01:48.530 ","End":"01:50.710","Text":"the total is 11."},{"Start":"01:50.710 ","End":"01:54.080","Text":"Even though lines 2 and 3 are identical"},{"Start":"01:54.080 ","End":"01:57.515","Text":"to the example above and all we did was swap the order,"},{"Start":"01:57.515 ","End":"01:59.600","Text":"the output is different."},{"Start":"01:59.600 ","End":"02:02.420","Text":"This trivial example illustrates the fact that sequence is"},{"Start":"02:02.420 ","End":"02:06.725","Text":"a fundamentally important idea in writing programs in imperative languages."},{"Start":"02:06.725 ","End":"02:09.140","Text":"It\u0027s up to the programmer to take account of the order"},{"Start":"02:09.140 ","End":"02:11.645","Text":"in which instructions are going to be executed."},{"Start":"02:11.645 ","End":"02:13.550","Text":"Well, what if you wanted to skip a line or"},{"Start":"02:13.550 ","End":"02:16.610","Text":"multiple lines of code depending on the circumstances?"},{"Start":"02:16.610 ","End":"02:20.375","Text":"This is exactly what conditional control structures are intended for."},{"Start":"02:20.375 ","End":"02:25.330","Text":"A conditional structure is a high-level programming language feature where execution"},{"Start":"02:25.330 ","End":"02:30.575","Text":"takes 1 of 2 possible paths depending on the value returned from a Boolean expression."},{"Start":"02:30.575 ","End":"02:34.310","Text":"Conditional structures allow us to choose whether a particular line or block of"},{"Start":"02:34.310 ","End":"02:38.705","Text":"code runs or not and use Boolean expressions to make the decision."},{"Start":"02:38.705 ","End":"02:42.665","Text":"You may have seen flowcharts used outside the context of programming,"},{"Start":"02:42.665 ","End":"02:45.920","Text":"where they used to show the steps that a process follows."},{"Start":"02:45.920 ","End":"02:51.245","Text":"Conditional statements are represented in flowcharts by a diamond symbol."},{"Start":"02:51.245 ","End":"02:55.040","Text":"Here we can see a Boolean expression where the value is stored in"},{"Start":"02:55.040 ","End":"02:59.575","Text":"variable A is being compared to the literal value 10."},{"Start":"02:59.575 ","End":"03:01.765","Text":"If A contains 10,"},{"Start":"03:01.765 ","End":"03:06.560","Text":"the expression evaluates to true and we follow the true path."},{"Start":"03:06.560 ","End":"03:08.525","Text":"If it doesn\u0027t contain 10,"},{"Start":"03:08.525 ","End":"03:14.420","Text":"the expression will evaluate to false and we follow the false path."},{"Start":"03:14.420 ","End":"03:17.150","Text":"Remember, a Boolean expression is one that results in"},{"Start":"03:17.150 ","End":"03:19.865","Text":"a value which is either true or false."},{"Start":"03:19.865 ","End":"03:24.810","Text":"Other examples would be tries is less than 6,"},{"Start":"03:24.810 ","End":"03:28.598","Text":"any value of tries less than 6 will evaluate to true,"},{"Start":"03:28.598 ","End":"03:30.994","Text":"any other values will give false."},{"Start":"03:30.994 ","End":"03:33.655","Text":"This expression uses and,"},{"Start":"03:33.655 ","End":"03:39.185","Text":"so will only give true for values above 7 and below 13,"},{"Start":"03:39.185 ","End":"03:41.480","Text":"so 8, 9, 10, 11,"},{"Start":"03:41.480 ","End":"03:43.243","Text":"12 give true,"},{"Start":"03:43.243 ","End":"03:45.640","Text":"anything else gives false."},{"Start":"03:45.640 ","End":"03:51.425","Text":"3 variables are being used in this expression with all joining 2 comparisons."},{"Start":"03:51.425 ","End":"03:56.960","Text":"This will evaluate to true if i is less than length or choice contains Q."},{"Start":"03:56.960 ","End":"04:02.179","Text":"Any other values for i and choice will result in an evaluation of false."},{"Start":"04:02.179 ","End":"04:04.385","Text":"There\u0027s lots going on in this example."},{"Start":"04:04.385 ","End":"04:09.380","Text":"We\u0027ve got 2 expressions joined by an and inside the brackets,"},{"Start":"04:09.380 ","End":"04:12.390","Text":"but as a not outside the brackets as well,"},{"Start":"04:12.390 ","End":"04:14.600","Text":"so that result will be flipped."},{"Start":"04:14.600 ","End":"04:21.769","Text":"You\u0027ll only get false here if tries is not 5 and password correct is not false."},{"Start":"04:21.769 ","End":"04:28.195","Text":"Any other values for tries and password correct in any combination will evaluate to true."},{"Start":"04:28.195 ","End":"04:32.900","Text":"Boolean variables can only be compared to the value true or false, like this example."},{"Start":"04:32.900 ","End":"04:38.945","Text":"However, you rarely see programs comparing a Boolean variable to true."},{"Start":"04:38.945 ","End":"04:43.025","Text":"Because just giving the name of the variable in an expression will give you a Boolean."},{"Start":"04:43.025 ","End":"04:45.140","Text":"If the variable contains true,"},{"Start":"04:45.140 ","End":"04:46.790","Text":"it evaluates to true."},{"Start":"04:46.790 ","End":"04:48.275","Text":"If it contains false,"},{"Start":"04:48.275 ","End":"04:50.000","Text":"it will evaluate to false."},{"Start":"04:50.000 ","End":"04:54.425","Text":"These last 3 lines are actually identical."},{"Start":"04:54.425 ","End":"04:57.800","Text":"The syntax for a conditional control structure starts with"},{"Start":"04:57.800 ","End":"05:01.570","Text":"the keyword if in most high-level languages."},{"Start":"05:01.570 ","End":"05:04.640","Text":"The keywords then followed with a Boolean expression,"},{"Start":"05:04.640 ","End":"05:07.775","Text":"which is to be evaluated and compared to true."},{"Start":"05:07.775 ","End":"05:10.220","Text":"If the evaluated value is true,"},{"Start":"05:10.220 ","End":"05:14.635","Text":"then the line or lines of code that follow will be executed."},{"Start":"05:14.635 ","End":"05:16.515","Text":"In C and Java,"},{"Start":"05:16.515 ","End":"05:20.090","Text":"the open brace more commonly called a curly bracket symbol,"},{"Start":"05:20.090 ","End":"05:24.470","Text":"starts the block and the closing one ends it."},{"Start":"05:24.470 ","End":"05:27.890","Text":"Everything within that block will be executed or"},{"Start":"05:27.890 ","End":"05:32.150","Text":"skipped depending on what the Boolean expression evaluated to."},{"Start":"05:32.150 ","End":"05:34.055","Text":"If it evaluated to true,"},{"Start":"05:34.055 ","End":"05:36.245","Text":"the lines in the block will be executed."},{"Start":"05:36.245 ","End":"05:39.140","Text":"If it evaluated to false, they\u0027ll be skipped."},{"Start":"05:39.140 ","End":"05:42.440","Text":"In Python, curly brackets aren\u0027t needed and the block is defined"},{"Start":"05:42.440 ","End":"05:46.000","Text":"mainly by indenting the statements inside the block."},{"Start":"05:46.000 ","End":"05:47.930","Text":"Here the green lines are indented,"},{"Start":"05:47.930 ","End":"05:50.345","Text":"which indicates they are part of the if block."},{"Start":"05:50.345 ","End":"05:53.240","Text":"It\u0027s not necessary to indent in C and Java,"},{"Start":"05:53.240 ","End":"05:54.560","Text":"the program will work,"},{"Start":"05:54.560 ","End":"05:58.355","Text":"but it\u0027s good practice to indent to make your code more readable."},{"Start":"05:58.355 ","End":"06:01.535","Text":"In Python, the indent is part of the syntax,"},{"Start":"06:01.535 ","End":"06:03.305","Text":"so it\u0027s not optional."},{"Start":"06:03.305 ","End":"06:05.839","Text":"Once the Boolean expression has been evaluated"},{"Start":"06:05.839 ","End":"06:08.525","Text":"and the block of code is executed or skipped,"},{"Start":"06:08.525 ","End":"06:13.430","Text":"execution then continues on from the end of the block."},{"Start":"06:13.430 ","End":"06:15.170","Text":"In this example in Java,"},{"Start":"06:15.170 ","End":"06:18.185","Text":"which will be almost identical in C and C Plus Plus,"},{"Start":"06:18.185 ","End":"06:21.680","Text":"a variable called tries might be used to keep"},{"Start":"06:21.680 ","End":"06:26.245","Text":"track of how many times a user has entered their password incorrectly."},{"Start":"06:26.245 ","End":"06:28.280","Text":"If we want to warn the user when they\u0027ve had"},{"Start":"06:28.280 ","End":"06:31.340","Text":"4 tries and therefore on their fifth and last try,"},{"Start":"06:31.340 ","End":"06:34.460","Text":"we could use this code which prints a message,"},{"Start":"06:34.460 ","End":"06:37.535","Text":"but only when you\u0027ve had your fourth try."},{"Start":"06:37.535 ","End":"06:45.030","Text":"The tries variable will always be incremented because that line\u0027s outside the if block."},{"Start":"06:45.030 ","End":"06:47.420","Text":"Whether tries contains 4 or not,"},{"Start":"06:47.420 ","End":"06:49.085","Text":"it will always run."},{"Start":"06:49.085 ","End":"06:51.080","Text":"We\u0027ll pause there for a moment."},{"Start":"06:51.080 ","End":"06:56.525","Text":"In the next video, we\u0027ll look at an extension of this if structure called an if-else."},{"Start":"06:56.525 ","End":"06:59.550","Text":"See you for that one in a moment."}],"ID":26827},{"Watched":false,"Name":"If Else Structure","Duration":"6m 38s","ChapterTopicVideoID":26019,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.905","Text":"Hello, welcome back."},{"Start":"00:01.905 ","End":"00:06.330","Text":"In the previous video, we saw how lines of code in a program can be run or skipped"},{"Start":"00:06.330 ","End":"00:11.880","Text":"depending on a Boolean expression using some encoder conditional control structure."},{"Start":"00:11.880 ","End":"00:15.465","Text":"We looked at an example using the keyword if."},{"Start":"00:15.465 ","End":"00:20.385","Text":"A slightly more powerful control structure is the so-called if else structure."},{"Start":"00:20.385 ","End":"00:23.910","Text":"Here we are again presented with a Boolean evaluation."},{"Start":"00:23.910 ","End":"00:27.810","Text":"But this time, rather than executing a block or skipping it,"},{"Start":"00:27.810 ","End":"00:31.230","Text":"we\u0027re able to choose between two alternative blocks."},{"Start":"00:31.230 ","End":"00:34.850","Text":"One or the other will be executed, but never both."},{"Start":"00:34.850 ","End":"00:36.980","Text":"Whichever one is executed,"},{"Start":"00:36.980 ","End":"00:40.049","Text":"execution continues on after the end of the whole if"},{"Start":"00:40.049 ","End":"00:43.535","Text":"else structure from the blue lines onward here."},{"Start":"00:43.535 ","End":"00:47.090","Text":"In this example, the Boolean expression being"},{"Start":"00:47.090 ","End":"00:50.840","Text":"evaluated will give true only when passwordLen"},{"Start":"00:50.840 ","End":"00:54.260","Text":"contains a value between 8 and 12 because it"},{"Start":"00:54.260 ","End":"00:58.879","Text":"must be greater than 7 and it must be less than 13."},{"Start":"00:58.879 ","End":"01:01.820","Text":"Anything else will give the value false."},{"Start":"01:01.820 ","End":"01:07.990","Text":"The first block following the if runs only if passwordLen contains values 8,"},{"Start":"01:07.990 ","End":"01:10.100","Text":"9, 10, 11, or 12."},{"Start":"01:10.100 ","End":"01:13.190","Text":"Otherwise, the else block will run."},{"Start":"01:13.190 ","End":"01:18.251","Text":"In either case, execution continues on from the end of the else block."},{"Start":"01:18.251 ","End":"01:22.099","Text":"In this case, outputting the message checks complete."},{"Start":"01:22.099 ","End":"01:25.340","Text":"A really important point to make here is that the else block"},{"Start":"01:25.340 ","End":"01:28.715","Text":"doesn\u0027t involve another Boolean evaluation."},{"Start":"01:28.715 ","End":"01:33.020","Text":"It\u0027s tied to the evaluation in the if statement."},{"Start":"01:33.020 ","End":"01:36.950","Text":"However, it is possible to have one if block tied to another if"},{"Start":"01:36.950 ","End":"01:40.655","Text":"block with both of them then tied to a final else."},{"Start":"01:40.655 ","End":"01:43.180","Text":"The first part here is just as before."},{"Start":"01:43.180 ","End":"01:47.945","Text":"But the last line doesn\u0027t say if on its own or else on its own."},{"Start":"01:47.945 ","End":"01:51.158","Text":"The two are combined together into an else"},{"Start":"01:51.158 ","End":"01:55.475","Text":"if and another Boolean expression is evaluated."},{"Start":"01:55.475 ","End":"02:00.320","Text":"This else if block then has its own statements inside the block,"},{"Start":"02:00.320 ","End":"02:05.705","Text":"and at the end of the block there follows an else with its own instructions."},{"Start":"02:05.705 ","End":"02:10.445","Text":"Notice that for else there\u0027s no Boolean expression to evaluate."},{"Start":"02:10.445 ","End":"02:14.660","Text":"Unlike above with the else if and the if,"},{"Start":"02:14.660 ","End":"02:17.795","Text":"both of which do have a Boolean expression."},{"Start":"02:17.795 ","End":"02:21.110","Text":"Here, if the first expression evaluates to true,"},{"Start":"02:21.110 ","End":"02:24.080","Text":"the green lines will run and everything else will be skipped,"},{"Start":"02:24.080 ","End":"02:26.360","Text":"and we continue on from the blue lines."},{"Start":"02:26.360 ","End":"02:29.630","Text":"If the first expression evaluated to false,"},{"Start":"02:29.630 ","End":"02:32.360","Text":"then expression 2 is evaluated."},{"Start":"02:32.360 ","End":"02:33.530","Text":"If that is true,"},{"Start":"02:33.530 ","End":"02:37.295","Text":"the red lines run and we continue on from the blue lines."},{"Start":"02:37.295 ","End":"02:42.365","Text":"If neither expression 1 was true or expression 2 was true,"},{"Start":"02:42.365 ","End":"02:46.460","Text":"then this else block comes into play and it would run"},{"Start":"02:46.460 ","End":"02:51.185","Text":"these lines in orange followed again by the lines in blue."},{"Start":"02:51.185 ","End":"02:54.024","Text":"Let\u0027s have a look at another example."},{"Start":"02:54.024 ","End":"02:57.935","Text":"Here the evaluations involve a variable called age,"},{"Start":"02:57.935 ","End":"03:02.060","Text":"which contains the age of someone trying to sign up for some service."},{"Start":"03:02.060 ","End":"03:05.180","Text":"If age contains a number less than 13,"},{"Start":"03:05.180 ","End":"03:07.650","Text":"the green lines will run."},{"Start":"03:07.650 ","End":"03:10.160","Text":"Then the message initial age checks"},{"Start":"03:10.160 ","End":"03:14.270","Text":"completed will be displayed as all the other blocks will be skipped."},{"Start":"03:14.270 ","End":"03:17.210","Text":"If the age is not less than 13,"},{"Start":"03:17.210 ","End":"03:24.140","Text":"then a second evaluation takes place to see if the age is less than 18."},{"Start":"03:24.140 ","End":"03:28.265","Text":"If it is, the red lines will run and again,"},{"Start":"03:28.265 ","End":"03:33.245","Text":"the message initial age checks will be completed at the end."},{"Start":"03:33.245 ","End":"03:38.870","Text":"If the age is not less than 13 and not less than 18,"},{"Start":"03:38.870 ","End":"03:43.025","Text":"then the else block comes into play and the lines in"},{"Start":"03:43.025 ","End":"03:47.180","Text":"orange will run before again the blue lines run."},{"Start":"03:47.180 ","End":"03:50.330","Text":"Note that no matter what value age contains,"},{"Start":"03:50.330 ","End":"03:54.320","Text":"only one of these 3 blocks is going to run,"},{"Start":"03:54.320 ","End":"03:56.605","Text":"and the other 2 will be skipped."},{"Start":"03:56.605 ","End":"04:00.575","Text":"We\u0027ll only have 1 else if in this example,"},{"Start":"04:00.575 ","End":"04:02.750","Text":"but you could have as many as you want."},{"Start":"04:02.750 ","End":"04:08.725","Text":"They must always follow the initial if and come before the final else block."},{"Start":"04:08.725 ","End":"04:11.475","Text":"Here\u0027s the same code in Python."},{"Start":"04:11.475 ","End":"04:13.625","Text":"There\u0027s no curly brackets here,"},{"Start":"04:13.625 ","End":"04:18.275","Text":"but you do see a colon which starts a block,"},{"Start":"04:18.275 ","End":"04:23.105","Text":"and the indents then determine what belongs inside a block."},{"Start":"04:23.105 ","End":"04:31.085","Text":"Also notice the keywords else and if are contracted into one word here, elif."},{"Start":"04:31.085 ","End":"04:35.770","Text":"Apart from that, it\u0027s very similar to the Java and C version."},{"Start":"04:35.770 ","End":"04:39.980","Text":"An alternative to else if is the use of a technique called nesting,"},{"Start":"04:39.980 ","End":"04:44.390","Text":"where one if else block is nestled inside another."},{"Start":"04:44.390 ","End":"04:48.890","Text":"Here we can see that a whole if else structure in green and blue"},{"Start":"04:48.890 ","End":"04:53.435","Text":"is inside the if block of another if else structure."},{"Start":"04:53.435 ","End":"05:00.995","Text":"We refer to these as an inner if else block and an outer if else block."},{"Start":"05:00.995 ","End":"05:03.140","Text":"The crucial visual cue here is"},{"Start":"05:03.140 ","End":"05:07.415","Text":"the further indentation of the blue and green statements here,"},{"Start":"05:07.415 ","End":"05:11.825","Text":"further in from the side of the screen within this inner if else block."},{"Start":"05:11.825 ","End":"05:15.895","Text":"What happens here is that Boolean expression 1 is evaluated,"},{"Start":"05:15.895 ","End":"05:18.000","Text":"and if it evaluates to true,"},{"Start":"05:18.000 ","End":"05:21.689","Text":"then the second expression is evaluated."},{"Start":"05:21.689 ","End":"05:27.890","Text":"The second expression will decide here whether the green block or the blue block runs."},{"Start":"05:27.890 ","End":"05:31.065","Text":"If expression 1 evaluated to false,"},{"Start":"05:31.065 ","End":"05:33.555","Text":"the if block of course will be skipped,"},{"Start":"05:33.555 ","End":"05:36.740","Text":"and so the outer else block will run."},{"Start":"05:36.740 ","End":"05:40.040","Text":"Hence, these orange lines are executed."},{"Start":"05:40.040 ","End":"05:42.710","Text":"Let\u0027s have a look at another example in Java."},{"Start":"05:42.710 ","End":"05:47.900","Text":"Here the variable month is check to see if it contains the value 2."},{"Start":"05:47.900 ","End":"05:51.460","Text":"If it is, then the inner if else structure runs,"},{"Start":"05:51.460 ","End":"05:57.140","Text":"otherwise the else structure and the overall outer else block runs."},{"Start":"05:57.140 ","End":"06:04.370","Text":"The nested if is checking a variable called leap year to see if it contains true."},{"Start":"06:04.370 ","End":"06:09.105","Text":"If it does, it will output the month has 29 days."},{"Start":"06:09.105 ","End":"06:10.425","Text":"If it\u0027s not true,"},{"Start":"06:10.425 ","End":"06:14.220","Text":"the else of the inner if else structure will run,"},{"Start":"06:14.220 ","End":"06:19.325","Text":"and then the month has 28 days will be output."},{"Start":"06:19.325 ","End":"06:22.310","Text":"It\u0027s possible to have multiple levels of nesting."},{"Start":"06:22.310 ","End":"06:24.785","Text":"We can have another one inside here if we wanted,"},{"Start":"06:24.785 ","End":"06:27.965","Text":"but the code then becomes quite hard to follow."},{"Start":"06:27.965 ","End":"06:29.960","Text":"In this final video in this section,"},{"Start":"06:29.960 ","End":"06:32.630","Text":"we\u0027ll look at an alternative called switch,"},{"Start":"06:32.630 ","End":"06:38.800","Text":"which may be more suited for some situations. I\u0027ll see you then."}],"ID":26828},{"Watched":false,"Name":"Switch Structure","Duration":"9m 9s","ChapterTopicVideoID":26020,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.475","Text":"Hello, everyone. Welcome back."},{"Start":"00:02.475 ","End":"00:06.510","Text":"We saw in the previous videos that conditional structures allow us to skip blocks"},{"Start":"00:06.510 ","End":"00:10.350","Text":"of code or run 1 block out of 2 alternatives,"},{"Start":"00:10.350 ","End":"00:12.405","Text":"the if block and the else block."},{"Start":"00:12.405 ","End":"00:17.145","Text":"We can also chain multiple if and else statements together using else-if."},{"Start":"00:17.145 ","End":"00:22.065","Text":"Nesting was the idea that 1 conditional structure can be embedded inside another one."},{"Start":"00:22.065 ","End":"00:28.020","Text":"Here we can see the if-else structure in blue is nested inside the outer if block."},{"Start":"00:28.020 ","End":"00:32.070","Text":"Whilst nesting allows us to have more complex and flexible code,"},{"Start":"00:32.070 ","End":"00:34.880","Text":"it\u0027s possible to have even more levels of nesting"},{"Start":"00:34.880 ","End":"00:37.700","Text":"than the one shown here in the example and if that\u0027s the case,"},{"Start":"00:37.700 ","End":"00:39.785","Text":"the code can be quite hard to follow."},{"Start":"00:39.785 ","End":"00:41.180","Text":"For this and other reasons,"},{"Start":"00:41.180 ","End":"00:46.130","Text":"some high-level languages provide an alternative mechanism called a switch structure."},{"Start":"00:46.130 ","End":"00:47.810","Text":"In a switch structure,"},{"Start":"00:47.810 ","End":"00:53.015","Text":"a value determines where the program should jump to an a list of possible statements."},{"Start":"00:53.015 ","End":"00:55.385","Text":"These are called cases."},{"Start":"00:55.385 ","End":"00:58.330","Text":"Another difference is that unlike if statements,"},{"Start":"00:58.330 ","End":"01:00.530","Text":"this is not a Boolean comparison."},{"Start":"01:00.530 ","End":"01:04.775","Text":"Remember true means an if block runs and false means it doesn\u0027t."},{"Start":"01:04.775 ","End":"01:06.380","Text":"With a switch statement,"},{"Start":"01:06.380 ","End":"01:07.850","Text":"it\u0027s an integer, char,"},{"Start":"01:07.850 ","End":"01:08.960","Text":"or in the case of Java,"},{"Start":"01:08.960 ","End":"01:14.530","Text":"a string that\u0027s being compared to a series of different values in each case block."},{"Start":"01:14.530 ","End":"01:17.530","Text":"If value contain the integer 1 in this example,"},{"Start":"01:17.530 ","End":"01:18.995","Text":"there would be a match,"},{"Start":"01:18.995 ","End":"01:22.060","Text":"an execution will continue from the first block."},{"Start":"01:22.060 ","End":"01:23.790","Text":"If it contain 2,"},{"Start":"01:23.790 ","End":"01:27.405","Text":"the second block and 3, the final block."},{"Start":"01:27.405 ","End":"01:33.335","Text":"In this example, a character contained inside the variable price code,"},{"Start":"01:33.335 ","End":"01:37.550","Text":"is being compared with 3 specific values, a, b,"},{"Start":"01:37.550 ","End":"01:42.470","Text":"and c. The relevant case block is executed for each particular value."},{"Start":"01:42.470 ","End":"01:46.055","Text":"For example, if price code contain b,"},{"Start":"01:46.055 ","End":"01:49.100","Text":"headphones would be output to the screen."},{"Start":"01:49.100 ","End":"01:51.455","Text":"If price code contained a,"},{"Start":"01:51.455 ","End":"01:55.100","Text":"cuddly toy would be output and if it contained c,"},{"Start":"01:55.100 ","End":"01:57.010","Text":"game would be output."},{"Start":"01:57.010 ","End":"02:00.330","Text":"For any other value than a, b, or c,"},{"Start":"02:00.330 ","End":"02:07.810","Text":"the default block will be executed in a similar way to else in the if-else construct."},{"Start":"02:07.810 ","End":"02:12.610","Text":"There\u0027s a keyword we\u0027ve not come across before here, break."},{"Start":"02:12.610 ","End":"02:17.980","Text":"What it does is break out of the surrounding overall control structure."},{"Start":"02:17.980 ","End":"02:21.205","Text":"An x it\u0027s the end of this overall block."},{"Start":"02:21.205 ","End":"02:24.880","Text":"With a switch statement is used to break out of the switch block once"},{"Start":"02:24.880 ","End":"02:30.760","Text":"a particular case has been found and the code inside that block has been executed."},{"Start":"02:30.760 ","End":"02:34.615","Text":"In this example, once it\u0027s printed, say cuddly toy,"},{"Start":"02:34.615 ","End":"02:40.605","Text":"we don\u0027t want it to print headphones and game as well hence the break."},{"Start":"02:40.605 ","End":"02:44.080","Text":"Note how there\u0027s no braces or curly brackets"},{"Start":"02:44.080 ","End":"02:47.365","Text":"around each case as they would be with an if and else."},{"Start":"02:47.365 ","End":"02:52.510","Text":"In a way the break is like a closing brace in an if or an else statement."},{"Start":"02:52.510 ","End":"02:56.665","Text":"But unlike a closing brace with if and else, which is compulsory,"},{"Start":"02:56.665 ","End":"02:58.990","Text":"the break statement is actually optional and"},{"Start":"02:58.990 ","End":"03:02.169","Text":"this can be seen better with another example."},{"Start":"03:02.169 ","End":"03:04.720","Text":"In this program, we\u0027re going to use an integer to"},{"Start":"03:04.720 ","End":"03:07.645","Text":"decide what to output when a game has ended."},{"Start":"03:07.645 ","End":"03:10.240","Text":"We want to print different messages depending on"},{"Start":"03:10.240 ","End":"03:13.015","Text":"what level of the game has been completed."},{"Start":"03:13.015 ","End":"03:14.740","Text":"Looking at the code,"},{"Start":"03:14.740 ","End":"03:17.274","Text":"you\u0027ll notice a couple of things have changed."},{"Start":"03:17.274 ","End":"03:23.180","Text":"Firstly, there are no break statements apart from the first case here."},{"Start":"03:23.180 ","End":"03:26.525","Text":"Secondly, there is no defaults option."},{"Start":"03:26.525 ","End":"03:28.910","Text":"This code, if we ran it,"},{"Start":"03:28.910 ","End":"03:31.790","Text":"would actually print several messages to the screen."},{"Start":"03:31.790 ","End":"03:37.535","Text":"Your experience is showing basic level completed and training level completed."},{"Start":"03:37.535 ","End":"03:41.870","Text":"The absence of a break statement means that the instructions keep on being"},{"Start":"03:41.870 ","End":"03:46.430","Text":"executed in sequence until the last line is reached."},{"Start":"03:46.430 ","End":"03:48.140","Text":"Although the variable level,"},{"Start":"03:48.140 ","End":"03:52.175","Text":"which is being used to select which case is executed,"},{"Start":"03:52.175 ","End":"03:56.120","Text":"contains 4 on entry to the switch statement,"},{"Start":"03:56.120 ","End":"04:00.133","Text":"there\u0027s no statement following case 4."},{"Start":"04:00.133 ","End":"04:04.610","Text":"So it continues on for the case statement for 3."},{"Start":"04:04.610 ","End":"04:07.820","Text":"Whether you\u0027ve reached level 4 or level 3 in this game,"},{"Start":"04:07.820 ","End":"04:10.145","Text":"the same messages will be displayed."},{"Start":"04:10.145 ","End":"04:14.750","Text":"The code then falls through into the cases for 2 and 1."},{"Start":"04:14.750 ","End":"04:18.260","Text":"Those lines will be executed and display those messages,"},{"Start":"04:18.260 ","End":"04:21.590","Text":"basic level completed and training level completed."},{"Start":"04:21.590 ","End":"04:23.825","Text":"Because there\u0027s no default case,"},{"Start":"04:23.825 ","End":"04:28.925","Text":"if a value less than 1 or greater than 5 is in the variable level,"},{"Start":"04:28.925 ","End":"04:35.480","Text":"nothing inside the block is executed so only game over will be printed."},{"Start":"04:35.480 ","End":"04:38.330","Text":"Not all languages support switch,"},{"Start":"04:38.330 ","End":"04:41.345","Text":"with Python being a notable example of one that doesn\u0027t."},{"Start":"04:41.345 ","End":"04:43.020","Text":"But if it is available to you,"},{"Start":"04:43.020 ","End":"04:47.075","Text":"you may be wondering when to use switch and when to use if-else."},{"Start":"04:47.075 ","End":"04:49.715","Text":"Here\u0027s a quick summary of the differences."},{"Start":"04:49.715 ","End":"04:53.030","Text":"Remember the way an if statement works is different to a switch"},{"Start":"04:53.030 ","End":"04:56.765","Text":"because if statements are based on Boolean evaluation,"},{"Start":"04:56.765 ","End":"05:01.685","Text":"for example, is the contents of 1 variable greater than the contents of another."},{"Start":"05:01.685 ","End":"05:05.270","Text":"With switch, execution jumps to a particular place in"},{"Start":"05:05.270 ","End":"05:09.845","Text":"the program depending on what value is in this specified variable."},{"Start":"05:09.845 ","End":"05:15.080","Text":"If statements organize the alternative blocks of code within else or"},{"Start":"05:15.080 ","End":"05:20.930","Text":"else-if where a switch uses case in an if-else structure,"},{"Start":"05:20.930 ","End":"05:24.950","Text":"only 1 block can be executed and the other one is skipped."},{"Start":"05:24.950 ","End":"05:29.135","Text":"This is also true of an if-else if chain of blocks."},{"Start":"05:29.135 ","End":"05:34.335","Text":"Only 1 block will run no matter how many else-if blocks exist."},{"Start":"05:34.335 ","End":"05:40.040","Text":"Switch is different because the case statement marks a starting point of execution and"},{"Start":"05:40.040 ","End":"05:42.380","Text":"code could continue on executing through"},{"Start":"05:42.380 ","End":"05:46.310","Text":"other cases until it encounters a break statement."},{"Start":"05:46.310 ","End":"05:52.310","Text":"In this way, the switch and case syntax is a little more flexible than the if-else."},{"Start":"05:52.310 ","End":"05:54.800","Text":"Because of the 1st point we made,"},{"Start":"05:54.800 ","End":"05:58.550","Text":"the if statement is a little bit more flexible in terms of choosing when"},{"Start":"05:58.550 ","End":"06:00.530","Text":"a particular block runs whereas"},{"Start":"06:00.530 ","End":"06:03.755","Text":"a switch statement is a little bit more limited than an if-else,"},{"Start":"06:03.755 ","End":"06:06.230","Text":"as the case is just a list of constants that"},{"Start":"06:06.230 ","End":"06:09.695","Text":"compared to the value being evaluated in the switch."},{"Start":"06:09.695 ","End":"06:13.340","Text":"This means more complex conditions like a range of values being"},{"Start":"06:13.340 ","End":"06:16.978","Text":"evaluated is possible within if combined with an and,"},{"Start":"06:16.978 ","End":"06:20.165","Text":"and that has no simple equivalent with a switch."},{"Start":"06:20.165 ","End":"06:25.970","Text":"The downside of the if statement\u0027s flexibility is that code can be harder to follow,"},{"Start":"06:25.970 ","End":"06:27.890","Text":"especially with nested ifs,"},{"Start":"06:27.890 ","End":"06:31.910","Text":"and there\u0027s a higher chance of introducing errors into our code as we develop it."},{"Start":"06:31.910 ","End":"06:33.680","Text":"In contrast, switch statements,"},{"Start":"06:33.680 ","End":"06:35.720","Text":"given they\u0027re slightly easier to read,"},{"Start":"06:35.720 ","End":"06:38.885","Text":"can be more straightforward to change and develop."},{"Start":"06:38.885 ","End":"06:44.885","Text":"Finally, there could be a slight speed penalty in using multiple if statements."},{"Start":"06:44.885 ","End":"06:46.760","Text":"Each time an if is encountered,"},{"Start":"06:46.760 ","End":"06:51.305","Text":"there needs to be a comparison made that results in a Boolean evaluation."},{"Start":"06:51.305 ","End":"06:53.870","Text":"With a long chain of if-else-if"},{"Start":"06:53.870 ","End":"06:57.890","Text":"statements or when there are multiple nested comparisons,"},{"Start":"06:57.890 ","End":"07:00.965","Text":"many comparisons may have to be made,"},{"Start":"07:00.965 ","End":"07:04.655","Text":"even if the code inside the block is going to be skipped."},{"Start":"07:04.655 ","End":"07:09.770","Text":"A switch statement doesn\u0027t have that disadvantage because a single comparison is made at"},{"Start":"07:09.770 ","End":"07:12.680","Text":"the beginning and the execution then continues"},{"Start":"07:12.680 ","End":"07:16.280","Text":"on from the relevant case until a break is encountered."},{"Start":"07:16.280 ","End":"07:20.240","Text":"Although it\u0027s dependent on how well the compiler or interpreter does its job,"},{"Start":"07:20.240 ","End":"07:23.045","Text":"you\u0027d expect a switch to be more efficient"},{"Start":"07:23.045 ","End":"07:26.690","Text":"than a series of if statements trying to do the same task."},{"Start":"07:26.690 ","End":"07:30.230","Text":"You can see here that the if structure is a little more"},{"Start":"07:30.230 ","End":"07:33.650","Text":"elegant than the equivalent switch because of the power of"},{"Start":"07:33.650 ","End":"07:36.140","Text":"Boolean expressions and the fact that"},{"Start":"07:36.140 ","End":"07:40.600","Text":"multiple conditions can be joined together with a logical and."},{"Start":"07:40.600 ","End":"07:44.900","Text":"In this example, if the range was wider than from 16-21,"},{"Start":"07:44.900 ","End":"07:49.760","Text":"say 16-41, the number of cases will become unmanageable."},{"Start":"07:49.760 ","End":"07:51.530","Text":"The if statement, by contrast,"},{"Start":"07:51.530 ","End":"07:54.335","Text":"just needs a single number to change."},{"Start":"07:54.335 ","End":"07:58.880","Text":"In general situations where there\u0027s a finite list of discrete values to be matched,"},{"Start":"07:58.880 ","End":"08:01.550","Text":"suggest a switch statement will be more useful."},{"Start":"08:01.550 ","End":"08:04.970","Text":"Anything that involves more complexity suggests an if statement"},{"Start":"08:04.970 ","End":"08:08.570","Text":"with a logical and comparison operators."},{"Start":"08:08.570 ","End":"08:12.800","Text":"There is, of course, nothing to stop you using both control structures together."},{"Start":"08:12.800 ","End":"08:17.375","Text":"The previous example could have used a default with an if-else inside it."},{"Start":"08:17.375 ","End":"08:22.340","Text":"The code will print a message if age contains a value less than 16 and"},{"Start":"08:22.340 ","End":"08:28.840","Text":"a different one if the age is over 21 because none of the cases above have been matched."},{"Start":"08:28.840 ","End":"08:34.895","Text":"There\u0027s also nothing to stop you putting a switch structure inside an if or else."},{"Start":"08:34.895 ","End":"08:38.270","Text":"In this way, we can have the best of both worlds allowing"},{"Start":"08:38.270 ","End":"08:41.870","Text":"code that\u0027s more readable, maintainable, and efficient."},{"Start":"08:41.870 ","End":"08:45.140","Text":"That\u0027s it on control structures."},{"Start":"08:45.140 ","End":"08:48.380","Text":"In this section, we learned how to explain the significance of"},{"Start":"08:48.380 ","End":"08:51.620","Text":"instructions being run in sequence in imperative languages,"},{"Start":"08:51.620 ","End":"08:55.685","Text":"to describe how high-level constructs allow code to be skipped,"},{"Start":"08:55.685 ","End":"09:01.070","Text":"and to evaluate which control structures suit a particular problem."},{"Start":"09:01.070 ","End":"09:04.100","Text":"I\u0027ll see you in the next topic which builds on this one to see"},{"Start":"09:04.100 ","End":"09:10.170","Text":"the high-level constructs available that allow us to repeat blocks of code. See you then."}],"ID":26829},{"Watched":false,"Name":"Exercise 1","Duration":"6m 50s","ChapterTopicVideoID":26447,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.760","Text":"Hello. Welcome to this first video where we work through"},{"Start":"00:02.760 ","End":"00:06.045","Text":"the first exercise on assignments and expressions,"},{"Start":"00:06.045 ","End":"00:09.990","Text":"aiming to build on our initial understanding of variables and data types."},{"Start":"00:09.990 ","End":"00:15.180","Text":"We, first of all, been asked to create a new project and open the Code Pad in Bluej,"},{"Start":"00:15.180 ","End":"00:17.925","Text":"and then to do the following activities in the Code Pad."},{"Start":"00:17.925 ","End":"00:22.230","Text":"In part A, we need to create a single line of code to create a Boolean variable,"},{"Start":"00:22.230 ","End":"00:24.510","Text":"and to call that variable is valid,"},{"Start":"00:24.510 ","End":"00:27.345","Text":"and to initialize it with the value true."},{"Start":"00:27.345 ","End":"00:32.040","Text":"Part B, we\u0027re asked to use the up arrow to retrieve the line we just typed in,"},{"Start":"00:32.040 ","End":"00:36.650","Text":"and to change the last part of the line so the value is false, not true,"},{"Start":"00:36.650 ","End":"00:42.495","Text":"and then explain why we get an error message when you press \"Enter\" to compile a line."},{"Start":"00:42.495 ","End":"00:44.210","Text":"Then finally in part C,"},{"Start":"00:44.210 ","End":"00:49.730","Text":"we\u0027re asked to correct that line to successfully change the value to false."},{"Start":"00:49.730 ","End":"00:52.250","Text":"Welcome to this first video where we work through"},{"Start":"00:52.250 ","End":"00:55.670","Text":"the exercise on expressions and assignments."},{"Start":"00:55.670 ","End":"00:59.150","Text":"Exercise 1 specifically with the aim of building on"},{"Start":"00:59.150 ","End":"01:02.660","Text":"our initial understanding of variables and data types."},{"Start":"01:02.660 ","End":"01:07.505","Text":"We\u0027ve been first asked in exercise 1 to create a new project."},{"Start":"01:07.505 ","End":"01:09.740","Text":"Open the Code Pad, as we know from before,"},{"Start":"01:09.740 ","End":"01:16.010","Text":"you cannot have a Code Pad unless you have a project to contain it within."},{"Start":"01:16.010 ","End":"01:20.600","Text":"We\u0027ll just give it a name and I can open up"},{"Start":"01:20.600 ","End":"01:26.210","Text":"the window here just to give myself a bit of space to see the responses, etc."},{"Start":"01:26.210 ","End":"01:30.500","Text":"What we\u0027ve been asked to do in part 1 is with a single line of code,"},{"Start":"01:30.500 ","End":"01:36.400","Text":"create a Boolean variable called is valid and to initialize it with the value true."},{"Start":"01:36.400 ","End":"01:38.840","Text":"As we know from previously,"},{"Start":"01:38.840 ","End":"01:41.390","Text":"to declare a variable in Java,"},{"Start":"01:41.390 ","End":"01:44.345","Text":"you need to state the data type first."},{"Start":"01:44.345 ","End":"01:46.190","Text":"In this case, it\u0027s Boolean,"},{"Start":"01:46.190 ","End":"01:48.997","Text":"then the identifier or the name,"},{"Start":"01:48.997 ","End":"01:53.075","Text":"in this case, we\u0027ve been asked to call it is valid in camel case."},{"Start":"01:53.075 ","End":"01:56.000","Text":"Then we\u0027ve been asked to initialize it with the value true."},{"Start":"01:56.000 ","End":"01:57.590","Text":"Now up until now,"},{"Start":"01:57.590 ","End":"02:01.565","Text":"we would\u0027ve ended this line with a semicolon or by pressing \"Enter\","},{"Start":"02:01.565 ","End":"02:03.320","Text":"and we wouldn\u0027t have given it a value."},{"Start":"02:03.320 ","End":"02:08.520","Text":"But now we\u0027ve been asked to assign a value whilst we are declaring the variables,"},{"Start":"02:08.520 ","End":"02:09.990","Text":"so we can go ahead and do that,"},{"Start":"02:09.990 ","End":"02:12.410","Text":"and we have been asked to give it valid true,"},{"Start":"02:12.410 ","End":"02:14.780","Text":"which in Java is all lowercase."},{"Start":"02:14.780 ","End":"02:17.990","Text":"Let\u0027s do that. I\u0027m going to put semicolon on the end as well,"},{"Start":"02:17.990 ","End":"02:20.850","Text":"because that\u0027s how lines should end."},{"Start":"02:21.290 ","End":"02:28.580","Text":"No problems there, it\u0027s created my variable and I can check if I want that the value"},{"Start":"02:28.580 ","End":"02:34.880","Text":"in there is what I expect and is indeed true and is all data type Boolean,"},{"Start":"02:34.880 ","End":"02:36.710","Text":"so it\u0027s done its job and I\u0027m going to expect"},{"Start":"02:36.710 ","End":"02:39.350","Text":"anything else because it\u0027s such a simple line of code."},{"Start":"02:39.350 ","End":"02:41.480","Text":"Now we\u0027ve been asked in part B to press"},{"Start":"02:41.480 ","End":"02:44.840","Text":"the up arrow key to true treat the line we just typed to."},{"Start":"02:44.840 ","End":"02:48.020","Text":"It would be this line that we just typed to and obviously,"},{"Start":"02:48.020 ","End":"02:49.670","Text":"you\u0027ve looked at a value if is valid as well,"},{"Start":"02:49.670 ","End":"02:50.780","Text":"so I\u0027ve skipped the overlap,"},{"Start":"02:50.780 ","End":"02:53.180","Text":"but here is the initial line and we\u0027ve just been"},{"Start":"02:53.180 ","End":"02:55.865","Text":"asked to change the value to false so I\u0027ll do that."},{"Start":"02:55.865 ","End":"03:00.590","Text":"Now we get an error message saying is valid is already defined."},{"Start":"03:00.590 ","End":"03:04.640","Text":"We\u0027ve been asked to explain why we get that error message."},{"Start":"03:04.640 ","End":"03:06.920","Text":"Was actually relatively straightforward."},{"Start":"03:06.920 ","End":"03:10.310","Text":"As we said, when you declare a variable in Java,"},{"Start":"03:10.310 ","End":"03:13.940","Text":"you need to give a data type and you can also assign a value."},{"Start":"03:13.940 ","End":"03:19.235","Text":"Now what we\u0027re trying to do is presumably assign a different value to this variable."},{"Start":"03:19.235 ","End":"03:22.940","Text":"What we cannot do is redefine the variable because"},{"Start":"03:22.940 ","End":"03:26.735","Text":"that\u0027s what we appear to be doing as far as Java is concerned."},{"Start":"03:26.735 ","End":"03:28.805","Text":"It\u0027s saying is valid is already defined"},{"Start":"03:28.805 ","End":"03:32.270","Text":"because we put the data type in front of is valid,"},{"Start":"03:32.270 ","End":"03:36.875","Text":"it assumes we\u0027re declaring a new variable called is valid,"},{"Start":"03:36.875 ","End":"03:39.755","Text":"but it already has a variable called is valid,"},{"Start":"03:39.755 ","End":"03:43.790","Text":"so refuses to let us do that and hence the error message."},{"Start":"03:43.790 ","End":"03:47.600","Text":"What I need to do to correct this for part C is I simply need to"},{"Start":"03:47.600 ","End":"03:51.455","Text":"remove the data type from the beginning."},{"Start":"03:51.455 ","End":"03:56.220","Text":"Now it understands that there is an existing variable called is valid,"},{"Start":"03:56.220 ","End":"03:58.480","Text":"is not declaring a new one and it just"},{"Start":"03:58.480 ","End":"04:01.495","Text":"wants to change the value of that existing variable."},{"Start":"04:01.495 ","End":"04:04.270","Text":"I\u0027ll go ahead and do that and no error this time"},{"Start":"04:04.270 ","End":"04:06.940","Text":"and if I look at the value of is valid again,"},{"Start":"04:06.940 ","End":"04:08.755","Text":"it is indeed false now,"},{"Start":"04:08.755 ","End":"04:10.405","Text":"whereas previously it was true."},{"Start":"04:10.405 ","End":"04:12.490","Text":"A very, very simple exercise,"},{"Start":"04:12.490 ","End":"04:16.330","Text":"but really just there to illustrate the difference between"},{"Start":"04:16.330 ","End":"04:20.320","Text":"declaring a variable and assigning a value to a variable."},{"Start":"04:20.320 ","End":"04:23.560","Text":"They\u0027re different things, although we can do both things on"},{"Start":"04:23.560 ","End":"04:28.180","Text":"one line as we did here and as we attempted to do here,"},{"Start":"04:28.180 ","End":"04:31.085","Text":"but we couldn\u0027t because the variable already existed so"},{"Start":"04:31.085 ","End":"04:34.165","Text":"this is an error that a beginner will quite often get."},{"Start":"04:34.165 ","End":"04:38.440","Text":"They\u0027ll forget to take the data type off the beginning when they\u0027re merely"},{"Start":"04:38.440 ","End":"04:43.495","Text":"assigning a new value to a variable that already exists."},{"Start":"04:43.495 ","End":"04:45.700","Text":"Hopefully, that makes sense now,"},{"Start":"04:45.700 ","End":"04:49.790","Text":"and I\u0027ll see you in the next exercise where we start working with"},{"Start":"04:49.790 ","End":"04:55.350","Text":"assignments of variables to other variables. I\u0027ll see you then."}],"ID":27350},{"Watched":false,"Name":"Exercise 2","Duration":"8m 2s","ChapterTopicVideoID":26448,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.725","Text":"Hello, welcome back."},{"Start":"00:01.725 ","End":"00:05.340","Text":"In this next exercise on assignment and expressions,"},{"Start":"00:05.340 ","End":"00:08.430","Text":"we\u0027ve been asked to within the same Code Pad as before,"},{"Start":"00:08.430 ","End":"00:10.395","Text":"create 2 integer variables,"},{"Start":"00:10.395 ","End":"00:13.260","Text":"num1 and num2 with no initial value given,"},{"Start":"00:13.260 ","End":"00:18.230","Text":"and then to assign the value 10 to num1."},{"Start":"00:18.230 ","End":"00:22.775","Text":"Then in part c, to assign the contents of num1 to num2."},{"Start":"00:22.775 ","End":"00:24.020","Text":"Then finally in part d,"},{"Start":"00:24.020 ","End":"00:28.775","Text":"to confirm the contents of num2 are what you would expect."},{"Start":"00:28.775 ","End":"00:32.360","Text":"We\u0027ve been asked to create 2 integer variables num1 and"},{"Start":"00:32.360 ","End":"00:36.495","Text":"num2 with no initial value given in part a."},{"Start":"00:36.495 ","End":"00:38.430","Text":"Let\u0027s go ahead and do that."},{"Start":"00:38.430 ","End":"00:41.130","Text":"It turns out there\u0027s a little trick you can do."},{"Start":"00:41.130 ","End":"00:44.000","Text":"If there are 2 variables that you want to declare,"},{"Start":"00:44.000 ","End":"00:45.905","Text":"you can declare them in 1 line,"},{"Start":"00:45.905 ","End":"00:48.350","Text":"so long as they are the same data type,"},{"Start":"00:48.350 ","End":"00:51.245","Text":"because both of these are int,"},{"Start":"00:51.245 ","End":"00:57.430","Text":"we can do that and you just simply separate the 2 variable names with a comma."},{"Start":"00:57.430 ","End":"01:02.160","Text":"It will happily declare both of those variables in 1 line,"},{"Start":"01:02.160 ","End":"01:03.740","Text":"I could do in 2 if I wanted to,"},{"Start":"01:03.740 ","End":"01:07.925","Text":"but I\u0027m just going to show you that it will work if you do it in 1 line."},{"Start":"01:07.925 ","End":"01:10.145","Text":"Just to prove that that\u0027s worked."},{"Start":"01:10.145 ","End":"01:16.430","Text":"Well, I just get num1\u0027s value is 0 and num2\u0027s value is also 0."},{"Start":"01:16.430 ","End":"01:18.740","Text":"That\u0027s what this message here is saying."},{"Start":"01:18.740 ","End":"01:21.995","Text":"By the way, it\u0027s always actually good practice to"},{"Start":"01:21.995 ","End":"01:25.700","Text":"assign a value to a variable when you declare it,"},{"Start":"01:25.700 ","End":"01:28.700","Text":"even if it will be given a default value,"},{"Start":"01:28.700 ","End":"01:33.275","Text":"you sometimes can\u0027t guarantee that on certain systems,"},{"Start":"01:33.275 ","End":"01:36.590","Text":"so its best practice is to actually always assign"},{"Start":"01:36.590 ","End":"01:41.285","Text":"a value to a variable when you\u0027re initially declaring it."},{"Start":"01:41.285 ","End":"01:43.760","Text":"That\u0027s the first part, part a."},{"Start":"01:43.760 ","End":"01:48.070","Text":"Then in part b, we\u0027ve been asked to assign the value 10 to num1."},{"Start":"01:48.070 ","End":"01:50.780","Text":"Remembering what we learned in the previous exercise,"},{"Start":"01:50.780 ","End":"01:52.865","Text":"I don\u0027t need to put the data type again."},{"Start":"01:52.865 ","End":"01:56.105","Text":"I simply need to write the variable name out."},{"Start":"01:56.105 ","End":"02:02.195","Text":"Num1 equals 10 is what I\u0027ve been asked to do and it\u0027s quite happy doing that."},{"Start":"02:02.195 ","End":"02:05.000","Text":"But part c is something we haven\u0027t seen before,"},{"Start":"02:05.000 ","End":"02:09.710","Text":"it\u0027s asking us to assign the contents of num1 to num2."},{"Start":"02:09.710 ","End":"02:14.630","Text":"Previously, we\u0027ve only ever assigned literal values to variables."},{"Start":"02:14.630 ","End":"02:19.500","Text":"Now, we\u0027re being asked to assign the contents of a variable to another variable so,"},{"Start":"02:19.500 ","End":"02:23.640","Text":"really, all we need to do here is understand which order we put things in."},{"Start":"02:23.640 ","End":"02:29.840","Text":"You\u0027ll remember from the video that we are supposed to put on the left-hand side,"},{"Start":"02:29.840 ","End":"02:33.904","Text":"the name of the variable that we wanted to store things into."},{"Start":"02:33.904 ","End":"02:38.465","Text":"Here, we\u0027ve been asked to assign the contents of num1 to num2."},{"Start":"02:38.465 ","End":"02:42.235","Text":"Num2 should go on the left-hand side here,"},{"Start":"02:42.235 ","End":"02:44.390","Text":"then follows the assignment operator,"},{"Start":"02:44.390 ","End":"02:47.705","Text":"which in Java is a single equals,"},{"Start":"02:47.705 ","End":"02:52.915","Text":"and then num1 is the value we want to assign to num2."},{"Start":"02:52.915 ","End":"02:55.500","Text":"I\u0027ll go ahead and do that, and it\u0027s done."},{"Start":"02:55.500 ","End":"02:58.790","Text":"It reflects back to me 10 I\u0027m not sure what is 10,"},{"Start":"02:58.790 ","End":"03:00.050","Text":"is it num1 or is it num2?"},{"Start":"03:00.050 ","End":"03:01.925","Text":"Let\u0027s have a look at the value of num2."},{"Start":"03:01.925 ","End":"03:03.375","Text":"Num2 is 10,"},{"Start":"03:03.375 ","End":"03:09.480","Text":"and we already know that num1 is 10 because we set its value over here."},{"Start":"03:09.480 ","End":"03:12.885","Text":"Now, num2 and num1 are 10."},{"Start":"03:12.885 ","End":"03:15.630","Text":"That\u0027s pretty much what we expect."},{"Start":"03:15.630 ","End":"03:22.715","Text":"All we\u0027ve really learned here is when you put the contents of 1 variable into another,"},{"Start":"03:22.715 ","End":"03:27.655","Text":"you get a copy of the variable value."},{"Start":"03:27.655 ","End":"03:31.060","Text":"It does not affect the value you\u0027re copying in."},{"Start":"03:31.060 ","End":"03:35.050","Text":"In this case, we were copying num1 into num2."},{"Start":"03:35.050 ","End":"03:37.165","Text":"Num2 got num1 value,"},{"Start":"03:37.165 ","End":"03:39.430","Text":"but num1 didn\u0027t change itself."},{"Start":"03:39.430 ","End":"03:43.720","Text":"You might think that when you\u0027re assigning a value from 1 variable to another,"},{"Start":"03:43.720 ","End":"03:45.655","Text":"you\u0027re removing the value somehow,"},{"Start":"03:45.655 ","End":"03:46.840","Text":"but you\u0027re not doing that."},{"Start":"03:46.840 ","End":"03:51.280","Text":"You\u0027re just producing a copy of the value and the copy of that value goes"},{"Start":"03:51.280 ","End":"03:57.175","Text":"into the variable on the left-hand side of the assignment operator."},{"Start":"03:57.175 ","End":"04:00.700","Text":"We\u0027ll do some more complex operations later on."},{"Start":"04:00.700 ","End":"04:04.645","Text":"But that\u0027s the most basic type of assignment of 1 variable to another."},{"Start":"04:04.645 ","End":"04:08.290","Text":"Essentially, we\u0027re evaluating an expression on the right-hand side"},{"Start":"04:08.290 ","End":"04:12.530","Text":"and because the expression simply contains the name of a variable,"},{"Start":"04:12.530 ","End":"04:16.815","Text":"the evaluation is just to give us the contents of that variable."},{"Start":"04:16.815 ","End":"04:22.355","Text":"Then the assignment then happens and it\u0027s stored into the variable on the left-hand side."},{"Start":"04:22.355 ","End":"04:24.545","Text":"Nice and simple for exercise 2."},{"Start":"04:24.545 ","End":"04:30.240","Text":"I\u0027ll see you in the next one where we work with another pair of variables. See you then."}],"ID":27351},{"Watched":false,"Name":"Exercise 3","Duration":"8m 12s","ChapterTopicVideoID":26449,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.580","Text":"Hello, welcome back again."},{"Start":"00:02.580 ","End":"00:04.890","Text":"In this exercise, we\u0027ve been asked to create"},{"Start":"00:04.890 ","End":"00:07.875","Text":"another pair of variables in the Code Pad once again,"},{"Start":"00:07.875 ","End":"00:13.455","Text":"this time to create a char variable and assign it the value a,"},{"Start":"00:13.455 ","End":"00:17.775","Text":"then to create a short variable with no initial value."},{"Start":"00:17.775 ","End":"00:20.580","Text":"Then in part c, we\u0027ve been asked to assign the contents of"},{"Start":"00:20.580 ","End":"00:25.620","Text":"the char variable to the short variable and explain what happens."},{"Start":"00:25.620 ","End":"00:30.405","Text":"In part d we\u0027re asked to do part c again,"},{"Start":"00:30.405 ","End":"00:34.770","Text":"but in front of the char variable name put the following characters exactly"},{"Start":"00:34.770 ","End":"00:39.240","Text":"as they appear so (short)."},{"Start":"00:39.240 ","End":"00:41.990","Text":"In part e, we\u0027re asked to look at the contents of"},{"Start":"00:41.990 ","End":"00:47.275","Text":"the short variable and explain why it contains the particular value that it contains."},{"Start":"00:47.275 ","End":"00:49.370","Text":"Moving on into part f,"},{"Start":"00:49.370 ","End":"00:51.110","Text":"we move on to Unicode characters."},{"Start":"00:51.110 ","End":"00:55.380","Text":"We\u0027re asked to assign a Unicode character \u0027\\u9000\u0027,"},{"Start":"00:56.650 ","End":"00:59.180","Text":"to the char variable."},{"Start":"00:59.180 ","End":"01:01.430","Text":"Then in part g, once again,"},{"Start":"01:01.430 ","End":"01:04.130","Text":"to assign the value of that char variable to"},{"Start":"01:04.130 ","End":"01:09.875","Text":"the short variable with short in brackets in front of the char variable name."},{"Start":"01:09.875 ","End":"01:14.690","Text":"Then in the final part to look at the contents of the short variable again, and again,"},{"Start":"01:14.690 ","End":"01:19.805","Text":"explain why it contains the particular value it contains and what has gone wrong."},{"Start":"01:19.805 ","End":"01:26.690","Text":"We first have been asked to create a char variable and assign it with the value a."},{"Start":"01:26.690 ","End":"01:28.490","Text":"Let\u0027s go ahead and do that."},{"Start":"01:28.490 ","End":"01:31.370","Text":"We haven\u0027t been told a identifier,"},{"Start":"01:31.370 ","End":"01:33.800","Text":"so I\u0027m going to call mine my char,"},{"Start":"01:33.800 ","End":"01:38.830","Text":"not particularly descriptive, but it\u0027ll do for purposes of this exercise."},{"Start":"01:38.830 ","End":"01:41.870","Text":"Note that when you\u0027re assigning a char value,"},{"Start":"01:41.870 ","End":"01:43.714","Text":"it\u0027s a single quote,"},{"Start":"01:43.714 ","End":"01:46.730","Text":"and it\u0027s closed with a single quote as well,"},{"Start":"01:46.730 ","End":"01:49.655","Text":"not speech marks, which is double-quotes,"},{"Start":"01:49.655 ","End":"01:52.220","Text":"which would be shifted to on most keyboards."},{"Start":"01:52.220 ","End":"01:56.180","Text":"It\u0027s just a single quote that\u0027s needed for a char. There we go."},{"Start":"01:56.180 ","End":"02:01.880","Text":"I\u0027ve defined my variable and it has a value just to check that value and sure enough,"},{"Start":"02:01.880 ","End":"02:05.795","Text":"it\u0027s a data type of char and it contains the value a."},{"Start":"02:05.795 ","End":"02:07.130","Text":"Then in the second part,"},{"Start":"02:07.130 ","End":"02:10.460","Text":"we\u0027ve been asked to create a short variable with no initial value."},{"Start":"02:10.460 ","End":"02:14.130","Text":"Fair enough, call it my short,"},{"Start":"02:14.130 ","End":"02:18.290","Text":"I\u0027ll be consistent and no initial value,"},{"Start":"02:18.290 ","End":"02:22.265","Text":"so I\u0027ll just end it with a semicolon just to prove It will"},{"Start":"02:22.265 ","End":"02:31.550","Text":"have an initial value and it\u0027s initialized to 0 by default by the Java system."},{"Start":"02:31.550 ","End":"02:34.880","Text":"That\u0027s fine. Now I\u0027m asked to assign"},{"Start":"02:34.880 ","End":"02:39.410","Text":"the contents of the char variable to the short variable."},{"Start":"02:39.410 ","End":"02:44.495","Text":"Assign the contents of the my char variable to the my short variables."},{"Start":"02:44.495 ","End":"02:50.720","Text":"My short comes first because it\u0027s the thing that I want to receive the value into,"},{"Start":"02:50.720 ","End":"02:55.970","Text":"and my char is on the right-hand side of the assignment operator."},{"Start":"02:55.970 ","End":"02:58.280","Text":"Let\u0027s see what happens if I try that."},{"Start":"02:58.280 ","End":"03:00.965","Text":"Unsurprisingly hopefully to you,"},{"Start":"03:00.965 ","End":"03:04.790","Text":"I get an error message and it says, incompatible types."},{"Start":"03:04.790 ","End":"03:07.414","Text":"However, what\u0027s interesting about this error message."},{"Start":"03:07.414 ","End":"03:12.710","Text":"It doesn\u0027t seem to be a closed book and it looks very similar to"},{"Start":"03:12.710 ","End":"03:15.890","Text":"some similar messages we had before when we were dealing with"},{"Start":"03:15.890 ","End":"03:19.450","Text":"floats and different sizes of integer and so on."},{"Start":"03:19.450 ","End":"03:24.670","Text":"It almost seems that it\u0027s possible to do this but we\u0027re not quite"},{"Start":"03:24.670 ","End":"03:26.680","Text":"going about it the right way because it\u0027s saying"},{"Start":"03:26.680 ","End":"03:30.175","Text":"possible lossy conversion from char to short."},{"Start":"03:30.175 ","End":"03:33.430","Text":"We will see that in the next part,"},{"Start":"03:33.430 ","End":"03:34.840","Text":"in part d,"},{"Start":"03:34.840 ","End":"03:38.350","Text":"where I\u0027ve been asked to take exactly what I had before,"},{"Start":"03:38.350 ","End":"03:48.435","Text":"but put the following characters (short) in front of my char and see what happens."},{"Start":"03:48.435 ","End":"03:55.545","Text":"Strangely, the error message goes away and I\u0027m reflected back the value 97."},{"Start":"03:55.545 ","End":"03:59.770","Text":"What we\u0027re seeing here is something called casting or it\u0027s also called"},{"Start":"03:59.770 ","End":"04:04.370","Text":"coercion where we\u0027re saying to the system,"},{"Start":"04:04.370 ","End":"04:11.025","Text":"I know that one of these things is a short data type and one is a char data type"},{"Start":"04:11.025 ","End":"04:14.420","Text":"and normally you cannot assign a variable"},{"Start":"04:14.420 ","End":"04:17.810","Text":"of one data type to a different data type but just,"},{"Start":"04:17.810 ","End":"04:25.160","Text":"for now, I\u0027d like you to pretend essentially that my Char is not a char, it\u0027s a short."},{"Start":"04:25.160 ","End":"04:28.250","Text":"If it can do it, the system will actually go ahead and try and"},{"Start":"04:28.250 ","End":"04:31.340","Text":"do it and this will work in C and other languages as well."},{"Start":"04:31.340 ","End":"04:34.625","Text":"What we\u0027ve done here is we\u0027ve cast my char,"},{"Start":"04:34.625 ","End":"04:36.650","Text":"which is a char into a short,"},{"Start":"04:36.650 ","End":"04:40.385","Text":"and then we\u0027ve been able to assign it into my short."},{"Start":"04:40.385 ","End":"04:43.325","Text":"The value 97 we\u0027re being asked,"},{"Start":"04:43.325 ","End":"04:46.940","Text":"why does it contain this value in part e?"},{"Start":"04:46.940 ","End":"04:54.770","Text":"We might be able to guess that the letter a actually has a value in the ASCII table,"},{"Start":"04:54.770 ","End":"04:58.295","Text":"and it happens to be a is 97."},{"Start":"04:58.295 ","End":"05:01.445","Text":"What has happened here is the system has said, all right,"},{"Start":"05:01.445 ","End":"05:05.330","Text":"I know this is a char and my char is not changed,"},{"Start":"05:05.330 ","End":"05:06.830","Text":"by the way, if I look at my chart,"},{"Start":"05:06.830 ","End":"05:13.400","Text":"it still contains a character a but my short now contains not 0 but 97,"},{"Start":"05:13.400 ","End":"05:19.385","Text":"which happens to be the ASCII value of the character that\u0027s stored in my chart."},{"Start":"05:19.385 ","End":"05:23.090","Text":"This statement here has basically said, \"Yes,"},{"Start":"05:23.090 ","End":"05:26.825","Text":"I know you can assign a char to a short,"},{"Start":"05:26.825 ","End":"05:33.350","Text":"but can you just pretend the char is a short and store it into my short variable\"."},{"Start":"05:33.350 ","End":"05:35.225","Text":"It has done, and it\u0027s worked."},{"Start":"05:35.225 ","End":"05:38.195","Text":"That could be useful in some situations."},{"Start":"05:38.195 ","End":"05:40.460","Text":"It does allow you to do it,"},{"Start":"05:40.460 ","End":"05:44.810","Text":"but there could be some issues and we\u0027ll see that in the subsequent parts."},{"Start":"05:44.810 ","End":"05:47.425","Text":"If we look at Part f,"},{"Start":"05:47.425 ","End":"05:50.105","Text":"it asks us to assign a Unicode character,"},{"Start":"05:50.105 ","End":"05:53.675","Text":"\\u9000 to a char variable. Let\u0027s go ahead and do that."},{"Start":"05:53.675 ","End":"05:58.910","Text":"The variable is called my char and we put a single quote, backslash,"},{"Start":"05:58.910 ","End":"06:06.720","Text":"not a forward slash u and then 9,000 has to be 4 digits, hexadecimal digits."},{"Start":"06:06.720 ","End":"06:11.870","Text":"There we go. Assign the value and I get a symbol from"},{"Start":"06:11.870 ","End":"06:17.600","Text":"the Unicode character space that is a symbol in the Chinese alphabet."},{"Start":"06:17.600 ","End":"06:19.895","Text":"We wouldn\u0027t call it an alphabet, I guess it\u0027s a symbol."},{"Start":"06:19.895 ","End":"06:21.440","Text":"There are thousands of symbols,"},{"Start":"06:21.440 ","End":"06:26.464","Text":"which is why they\u0027re so high up in the Chinese symbols range,"},{"Start":"06:26.464 ","End":"06:28.340","Text":"and we call this symbol C, J, K by the way,"},{"Start":"06:28.340 ","End":"06:32.420","Text":"because Japanese and Korean also fall into the same range."},{"Start":"06:32.420 ","End":"06:37.125","Text":"There\u0027s a C, J, K symbol in my char now,"},{"Start":"06:37.125 ","End":"06:40.790","Text":"and correct me now I can do stuff with that, I can display it,"},{"Start":"06:40.790 ","End":"06:44.750","Text":"or I can search for it because it\u0027s in a variable now in a char variable."},{"Start":"06:44.750 ","End":"06:52.395","Text":"But let\u0027s try and do what we did before and assign this value into my short."},{"Start":"06:52.395 ","End":"06:54.830","Text":"My char now has a different value in it,"},{"Start":"06:54.830 ","End":"07:01.355","Text":"which is that character represented by the Unicode value 9,000 hex."},{"Start":"07:01.355 ","End":"07:04.640","Text":"Let\u0027s try and do what we did before and we know it worked before I got"},{"Start":"07:04.640 ","End":"07:09.710","Text":"97 into my short when I had the letter a in there."},{"Start":"07:09.710 ","End":"07:11.665","Text":"Let\u0027s see what happens now."},{"Start":"07:11.665 ","End":"07:16.265","Text":"I get a negative number, very strange."},{"Start":"07:16.265 ","End":"07:20.210","Text":"Now, why would I have got a negative number?"},{"Start":"07:20.210 ","End":"07:25.415","Text":"Why does short contain that value I\u0027m being asked in part h?"},{"Start":"07:25.415 ","End":"07:29.000","Text":"Well the reason is the size of short,"},{"Start":"07:29.000 ","End":"07:32.540","Text":"short remember is a 16-bit number,"},{"Start":"07:32.540 ","End":"07:35.705","Text":"but it\u0027s a signed 16-bit number so actually,"},{"Start":"07:35.705 ","End":"07:39.965","Text":"the maximum value you can have is a 15-bit number,"},{"Start":"07:39.965 ","End":"07:42.710","Text":"which is 3, 2, 7, 6, 7."},{"Start":"07:42.710 ","End":"07:47.390","Text":"It just so happens that 9,000 hex is a bigger number than 3,"},{"Start":"07:47.390 ","End":"07:52.025","Text":"2, 7, 6, 7, it\u0027s actually 36,864."},{"Start":"07:52.025 ","End":"07:56.225","Text":"What\u0027s happening here is I\u0027m going outside the range that can"},{"Start":"07:56.225 ","End":"08:00.740","Text":"be displayed in 15 bits or can be encoded in 15 bits."},{"Start":"08:00.740 ","End":"08:04.130","Text":"It\u0027s wrapped around through a negative value."},{"Start":"08:04.130 ","End":"08:10.760","Text":"I think really all this illustrates is although we can sometimes convert"},{"Start":"08:10.760 ","End":"08:14.420","Text":"one data type into another temporarily for the purposes"},{"Start":"08:14.420 ","End":"08:18.170","Text":"of an assignment by using this costing syntax,"},{"Start":"08:18.170 ","End":"08:22.075","Text":"which is to put a data type in brackets ahead of your variable name,"},{"Start":"08:22.075 ","End":"08:25.520","Text":"it can sometimes have unexpected effects"},{"Start":"08:25.520 ","End":"08:28.910","Text":"so you\u0027ve got to be very careful if you\u0027re doing this."},{"Start":"08:28.910 ","End":"08:30.829","Text":"If you\u0027re using, for example,"},{"Start":"08:30.829 ","End":"08:33.740","Text":"7-bit ASCII characters, no problem,"},{"Start":"08:33.740 ","End":"08:37.280","Text":"you can convert an integer that is values from 0 to"},{"Start":"08:37.280 ","End":"08:41.690","Text":"127 into an ASCII value from 0 to 127."},{"Start":"08:41.690 ","End":"08:44.900","Text":"No problem. But if it\u0027s anything else,"},{"Start":"08:44.900 ","End":"08:46.805","Text":"you\u0027ve got to be very careful."},{"Start":"08:46.805 ","End":"08:52.505","Text":"This short might, on the surface seem okay because it\u0027s 16 bits and so is Unicode,"},{"Start":"08:52.505 ","End":"08:59.810","Text":"but actually the short is 15 bits in the positive direction and negative direction,"},{"Start":"08:59.810 ","End":"09:02.075","Text":"and one bit is used for the sign so"},{"Start":"09:02.075 ","End":"09:06.210","Text":"it\u0027s potentially an area where you can have a problem."},{"Start":"09:06.210 ","End":"09:10.010","Text":"This exercise has shown you that you can\u0027t"},{"Start":"09:10.010 ","End":"09:16.145","Text":"normally put a variable of one data type into another variable of a different data type"},{"Start":"09:16.145 ","End":"09:21.560","Text":"but you can coerce one variable to temporarily pretend it\u0027s"},{"Start":"09:21.560 ","End":"09:24.560","Text":"a different type but that may or may not"},{"Start":"09:24.560 ","End":"09:27.825","Text":"cause problems and it\u0027s just something to be aware of."},{"Start":"09:27.825 ","End":"09:32.120","Text":"Generally, remember that data types are there to enforce"},{"Start":"09:32.120 ","End":"09:37.700","Text":"some constraints on the variable so they\u0027re there for a reason and it can be overwritten,"},{"Start":"09:37.700 ","End":"09:40.670","Text":"but just need to be very careful if you\u0027re going to do that."},{"Start":"09:40.670 ","End":"09:42.500","Text":"That\u0027s it for this exercise."},{"Start":"09:42.500 ","End":"09:44.970","Text":"I\u0027ll see for the next one."}],"ID":27352},{"Watched":false,"Name":"Exercise 4","Duration":"11m 13s","ChapterTopicVideoID":26443,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.415","Text":"Hello. Welcome back to the next video on the exercises on assignments and expressions."},{"Start":"00:05.415 ","End":"00:09.450","Text":"Here we\u0027ve been asked to create a 3rd integer variable in Code Pad called"},{"Start":"00:09.450 ","End":"00:14.910","Text":"num3 to complement the 2 integer variables we created in an earlier exercise."},{"Start":"00:14.910 ","End":"00:19.200","Text":"In part a, we\u0027ve been asked to assign the value 10 to num1,"},{"Start":"00:19.200 ","End":"00:21.120","Text":"20 to num2,"},{"Start":"00:21.120 ","End":"00:23.055","Text":"and 4 to num3,"},{"Start":"00:23.055 ","End":"00:26.250","Text":"and then check the contents of all 3 of those variables."},{"Start":"00:26.250 ","End":"00:31.980","Text":"In part b, we\u0027ve been asked to create a single expression involving all 3 of"},{"Start":"00:31.980 ","End":"00:38.210","Text":"those variables that adds num1 to num2 divided by num3,"},{"Start":"00:38.210 ","End":"00:41.830","Text":"and then note results of that evaluation."},{"Start":"00:41.830 ","End":"00:45.410","Text":"In part c, we\u0027ve been asked to take that same expression,"},{"Start":"00:45.410 ","End":"00:48.470","Text":"but put brackets around the addition of num1 and"},{"Start":"00:48.470 ","End":"00:52.495","Text":"num2 and then explain the resulting evaluation."},{"Start":"00:52.495 ","End":"00:54.325","Text":"Then finally, in part d,"},{"Start":"00:54.325 ","End":"00:59.270","Text":"I\u0027ve been asked to use the same expression again as part c,"},{"Start":"00:59.270 ","End":"01:02.660","Text":"but to use the modulo operation this time instead of"},{"Start":"01:02.660 ","End":"01:06.950","Text":"the divide operation and to explain the resulting evaluation."},{"Start":"01:06.950 ","End":"01:13.070","Text":"In question 4, we\u0027ve been asked to create a 3rd integer variable in co bad num3."},{"Start":"01:13.070 ","End":"01:16.250","Text":"We already created num1 and 2 in exercise 2."},{"Start":"01:16.250 ","End":"01:19.145","Text":"I\u0027ve actually got rid of mine because I\u0027ve started a new session."},{"Start":"01:19.145 ","End":"01:22.130","Text":"But you only need to put all of these in."},{"Start":"01:22.130 ","End":"01:24.800","Text":"I\u0027m going to create all 3 variables again."},{"Start":"01:24.800 ","End":"01:28.505","Text":"As I said, if you already still have num1 and num2,"},{"Start":"01:28.505 ","End":"01:30.304","Text":"you just need to create num3."},{"Start":"01:30.304 ","End":"01:36.430","Text":"Now, I have my 3 variables and part a asks me to assign the value 10 to num1,"},{"Start":"01:36.430 ","End":"01:38.980","Text":"20 to num2,"},{"Start":"01:39.170 ","End":"01:42.300","Text":"and 4 to num3."},{"Start":"01:42.300 ","End":"01:46.565","Text":"In part b, it now ask me to create a single expression involving"},{"Start":"01:46.565 ","End":"01:51.795","Text":"all 3 variables that adds num1 to num2 divided by num3."},{"Start":"01:51.795 ","End":"01:55.310","Text":"I haven\u0027t been told to store those values anywhere."},{"Start":"01:55.310 ","End":"01:59.660","Text":"I\u0027ve simply been asked to create an expression involving those 3 variables."},{"Start":"01:59.660 ","End":"02:01.580","Text":"That sounds straightforward enough."},{"Start":"02:01.580 ","End":"02:10.065","Text":"Num1 gets added to num2 divided by num3."},{"Start":"02:10.065 ","End":"02:12.825","Text":"It will evaluate to 15."},{"Start":"02:12.825 ","End":"02:14.305","Text":"Then part c,"},{"Start":"02:14.305 ","End":"02:18.260","Text":"I have been asked to put brackets around the addition of num1 and"},{"Start":"02:18.260 ","End":"02:23.240","Text":"2 and explain the evaluation that results from that."},{"Start":"02:23.240 ","End":"02:27.230","Text":"I\u0027ll just do our power to get back what I\u0027ve just typed."},{"Start":"02:27.230 ","End":"02:28.820","Text":"I\u0027ll do as I\u0027ve been asked,"},{"Start":"02:28.820 ","End":"02:36.015","Text":"which is to put brackets around num1 plus num2 and the value I get is 7."},{"Start":"02:36.015 ","End":"02:40.550","Text":"How can I explain the difference between those 2 evaluations?"},{"Start":"02:40.550 ","End":"02:42.350","Text":"Well, the first one here,"},{"Start":"02:42.350 ","End":"02:46.010","Text":"as we know the order of precedence comes in here."},{"Start":"02:46.010 ","End":"02:49.415","Text":"Normally we\u0027d evaluate from left to right, however,"},{"Start":"02:49.415 ","End":"02:55.415","Text":"some operations have a greater precedence than others and division and multiplication"},{"Start":"02:55.415 ","End":"03:02.089","Text":"would be an example of something that has a higher precedence than plus and minus."},{"Start":"03:02.089 ","End":"03:04.655","Text":"The division will happen first."},{"Start":"03:04.655 ","End":"03:11.045","Text":"Therefore, num2 will be divided by num3 and the result of that will be added to num1."},{"Start":"03:11.045 ","End":"03:12.950","Text":"That\u0027s exactly what we saw."},{"Start":"03:12.950 ","End":"03:18.485","Text":"Num2 was 20, num3 was 4."},{"Start":"03:18.485 ","End":"03:22.455","Text":"So 20 was divided by 4,"},{"Start":"03:22.455 ","End":"03:24.615","Text":"which will give us 5, of course,"},{"Start":"03:24.615 ","End":"03:28.235","Text":"and then it was added to num1 because num1 had 10 in it,"},{"Start":"03:28.235 ","End":"03:32.045","Text":"the result was 15 as we would expect."},{"Start":"03:32.045 ","End":"03:37.700","Text":"The result of putting brackets around num1 and num2,"},{"Start":"03:37.700 ","End":"03:40.750","Text":"brackets have the highest order of precedence of all."},{"Start":"03:40.750 ","End":"03:43.415","Text":"So they will be evaluated first,"},{"Start":"03:43.415 ","End":"03:44.750","Text":"and then the division,"},{"Start":"03:44.750 ","End":"03:47.015","Text":"although it has a higher precedence, now,"},{"Start":"03:47.015 ","End":"03:49.550","Text":"will be overridden by the brackets."},{"Start":"03:49.550 ","End":"03:52.010","Text":"It has a higher precedence than plus that is to say,"},{"Start":"03:52.010 ","End":"03:56.390","Text":"as it did here, the brackets now will be evaluated first."},{"Start":"03:56.390 ","End":"03:59.395","Text":"Num1 will be added to num2."},{"Start":"03:59.395 ","End":"04:05.455","Text":"Therefore, we\u0027d have 30 and then 30 is divided by num3, which is 4."},{"Start":"04:05.455 ","End":"04:07.120","Text":"Now, why do we get 7?"},{"Start":"04:07.120 ","End":"04:13.180","Text":"Because 30 divided by 4 is 28 with a remainder and"},{"Start":"04:13.180 ","End":"04:15.820","Text":"we only ask to give the integer part"},{"Start":"04:15.820 ","End":"04:19.404","Text":"because all these variables involved are integer variables."},{"Start":"04:19.404 ","End":"04:22.630","Text":"Therefore, the result of the expression would also be an integer,"},{"Start":"04:22.630 ","End":"04:26.140","Text":"and it\u0027s evaluated to the value 7."},{"Start":"04:26.140 ","End":"04:28.690","Text":"In part d, we\u0027ve been asked to use"},{"Start":"04:28.690 ","End":"04:32.095","Text":"exactly the same expression as part c, which was this one,"},{"Start":"04:32.095 ","End":"04:37.894","Text":"but to change the divide operator to the percent operator,"},{"Start":"04:37.894 ","End":"04:42.800","Text":"which means modulo and to explain the results of the evaluation."},{"Start":"04:42.800 ","End":"04:44.450","Text":"Now, we get 2."},{"Start":"04:44.450 ","End":"04:46.622","Text":"Going through those numbers again,"},{"Start":"04:46.622 ","End":"04:50.330","Text":"what we\u0027re seeing is num1 plus num2,"},{"Start":"04:50.330 ","End":"04:54.760","Text":"as we said, was 30 divided by 4."},{"Start":"04:54.760 ","End":"04:58.070","Text":"We are asked to give the remainder when we divide by 4."},{"Start":"04:58.070 ","End":"05:00.545","Text":"Not the quotient, but the remainder."},{"Start":"05:00.545 ","End":"05:03.870","Text":"The remainder when we divide 30 by 4,"},{"Start":"05:03.870 ","End":"05:08.645","Text":"we get 28 and then the remainder of 2,"},{"Start":"05:08.645 ","End":"05:11.165","Text":"so the result is 2."},{"Start":"05:11.165 ","End":"05:15.980","Text":"It\u0027s showing really the difference between the division and the modulo operators,"},{"Start":"05:15.980 ","End":"05:17.315","Text":"they\u0027re obviously related,"},{"Start":"05:17.315 ","End":"05:19.790","Text":"and how that applies to integers."},{"Start":"05:19.790 ","End":"05:25.125","Text":"We also saw how precedence is affected by brackets."},{"Start":"05:25.125 ","End":"05:28.730","Text":"This was a very straightforward expression involving"},{"Start":"05:28.730 ","End":"05:32.239","Text":"just a couple of numbers, 3 different variables."},{"Start":"05:32.239 ","End":"05:35.660","Text":"In fact, we can have a play around with this till our heart is"},{"Start":"05:35.660 ","End":"05:39.170","Text":"content by just typing in values and seeing how they\u0027re evaluated."},{"Start":"05:39.170 ","End":"05:41.660","Text":"These were variables, but if we wanted to,"},{"Start":"05:41.660 ","End":"05:46.940","Text":"we could put literals in here if we wanted to see what the effect would"},{"Start":"05:46.940 ","End":"05:53.855","Text":"be and how a set of brackets could be used to affect the order evaluation."},{"Start":"05:53.855 ","End":"05:56.750","Text":"You might be able to predict what you\u0027d get from this value."},{"Start":"05:56.750 ","End":"06:01.834","Text":"For example, what we\u0027ve got is 12 times 3 is going to happen first,"},{"Start":"06:01.834 ","End":"06:05.160","Text":"and that would give us 36."},{"Start":"06:05.160 ","End":"06:08.190","Text":"Then we minus 3 plus 4,"},{"Start":"06:08.190 ","End":"06:09.475","Text":"which is 7,"},{"Start":"06:09.475 ","End":"06:11.378","Text":"and that, obviously, gives us 29."},{"Start":"06:11.378 ","End":"06:12.950","Text":"Have a play around with this."},{"Start":"06:12.950 ","End":"06:16.730","Text":"The expressions can involve a variable or they can involve literals,"},{"Start":"06:16.730 ","End":"06:20.345","Text":"but they eventually will be evaluated and return a value."},{"Start":"06:20.345 ","End":"06:23.240","Text":"Of course that value could be stored into a variable."},{"Start":"06:23.240 ","End":"06:24.770","Text":"We haven\u0027t done that here."},{"Start":"06:24.770 ","End":"06:29.735","Text":"We weren\u0027t asked to, but it\u0027s probably going to happen in a real program."},{"Start":"06:29.735 ","End":"06:34.220","Text":"That\u0027s it for very simple expressions using some of"},{"Start":"06:34.220 ","End":"06:39.990","Text":"the mathematical operators and we\u0027re done for question 4."}],"ID":27353},{"Watched":false,"Name":"Exercise 5","Duration":"12m 49s","ChapterTopicVideoID":26444,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.220","Text":"Hello, welcome back. In this exercise,"},{"Start":"00:02.220 ","End":"00:05.280","Text":"we\u0027ve been asked to use the same variables as in the previous exercise,"},{"Start":"00:05.280 ","End":"00:08.085","Text":"integer variables from num1 to num3."},{"Start":"00:08.085 ","End":"00:10.830","Text":"In part a, we\u0027ve been asked to assign the value 7"},{"Start":"00:10.830 ","End":"00:13.980","Text":"to variable num1 and 8 to variable num2."},{"Start":"00:13.980 ","End":"00:18.000","Text":"Then in part b, which has got some sub-questions we\u0027ve been asked,"},{"Start":"00:18.000 ","End":"00:20.040","Text":"without using any other variables,"},{"Start":"00:20.040 ","End":"00:22.980","Text":"to use the comparison or relational operators."},{"Start":"00:22.980 ","End":"00:26.820","Text":"As they are also known in the Code Pad to test first of all,"},{"Start":"00:26.820 ","End":"00:29.115","Text":"if num1 and num2 are equal."},{"Start":"00:29.115 ","End":"00:30.810","Text":"Then in part 2,"},{"Start":"00:30.810 ","End":"00:34.245","Text":"if num1 and num2 are not equal,"},{"Start":"00:34.245 ","End":"00:39.000","Text":"in part b iii is num1 greater than num2,"},{"Start":"00:39.000 ","End":"00:43.589","Text":"and in part b iv is num1 less than num2."},{"Start":"00:43.589 ","End":"00:49.310","Text":"Then in part c, we\u0027ve been asked to change the value of num2 to 7 and then retest to"},{"Start":"00:49.310 ","End":"00:55.100","Text":"see if in part c1 num1 is greater than or equal to num2."},{"Start":"00:55.100 ","End":"01:00.145","Text":"In part c2, if num1 is less than or equal to num2."},{"Start":"01:00.145 ","End":"01:02.360","Text":"In the next part of the exercise,"},{"Start":"01:02.360 ","End":"01:04.325","Text":"we use the logical operators."},{"Start":"01:04.325 ","End":"01:09.360","Text":"Part d asks us to assign the value 9 to num3."},{"Start":"01:09.360 ","End":"01:14.180","Text":"Then we use the logical and operator to create a single expression that"},{"Start":"01:14.180 ","End":"01:20.305","Text":"evaluates whether num2 is greater than 5 and less than 10."},{"Start":"01:20.305 ","End":"01:23.905","Text":"In part f, we\u0027re asked to change the value of num2 to 5,"},{"Start":"01:23.905 ","End":"01:27.775","Text":"then run the expression above again, in part g,"},{"Start":"01:27.775 ","End":"01:33.530","Text":"we\u0027re asked to use the logical or operator instead to create a single expression that"},{"Start":"01:33.530 ","End":"01:40.585","Text":"evaluates whether num1 is less than num2 or num3 is equal to 11."},{"Start":"01:40.585 ","End":"01:41.870","Text":"In part h,"},{"Start":"01:41.870 ","End":"01:45.440","Text":"we\u0027re asked to change the value of num3 to 11 and run"},{"Start":"01:45.440 ","End":"01:50.125","Text":"the expression from part f again to see if the evaluation changes."},{"Start":"01:50.125 ","End":"01:55.550","Text":"Then finally, we\u0027re asked to create our own expression using a combination of"},{"Start":"01:55.550 ","End":"01:59.030","Text":"logical and comparison operators and to include"},{"Start":"01:59.030 ","End":"02:02.890","Text":"the not operator and brackets to change the order of evaluation."},{"Start":"02:02.890 ","End":"02:05.210","Text":"We\u0027re asked to change the value of at least one of"},{"Start":"02:05.210 ","End":"02:09.635","Text":"our variables and to see the effect on the evaluation."},{"Start":"02:09.635 ","End":"02:12.440","Text":"In this exercise number 5,"},{"Start":"02:12.440 ","End":"02:16.340","Text":"we\u0027ve been asked to use the same variables as in Exercise 4."},{"Start":"02:16.340 ","End":"02:20.075","Text":"We add num1 to num3 or integer variables,"},{"Start":"02:20.075 ","End":"02:24.455","Text":"and to perform various steps in the code patterns before."},{"Start":"02:24.455 ","End":"02:28.820","Text":"The first step in part a is to assign num1,"},{"Start":"02:28.820 ","End":"02:30.495","Text":"the value 7,"},{"Start":"02:30.495 ","End":"02:34.080","Text":"and num2, the value 8."},{"Start":"02:34.080 ","End":"02:35.835","Text":"Let\u0027s go ahead and do that."},{"Start":"02:35.835 ","End":"02:37.960","Text":"Then in part b,"},{"Start":"02:37.960 ","End":"02:42.230","Text":"we\u0027re being asked to not use any other variables but to use the comparison,"},{"Start":"02:42.230 ","End":"02:46.220","Text":"also known as relational operators in Code Pad to test"},{"Start":"02:46.220 ","End":"02:52.340","Text":"various logical tests using comparison operators."},{"Start":"02:52.340 ","End":"02:54.980","Text":"The first one b part 1,"},{"Start":"02:54.980 ","End":"02:59.830","Text":"is asking to see if num1 and num2 are equal."},{"Start":"02:59.830 ","End":"03:05.000","Text":"First trap you could follow in here is to use a single equal sign."},{"Start":"03:05.000 ","End":"03:09.230","Text":"Remember the single equal sign means, assign a value."},{"Start":"03:09.230 ","End":"03:14.465","Text":"Double equals sign is the comparison operator in Java."},{"Start":"03:14.465 ","End":"03:17.465","Text":"We\u0027re comparing one value to another."},{"Start":"03:17.465 ","End":"03:19.465","Text":"In this expression we\u0027re saying,"},{"Start":"03:19.465 ","End":"03:21.905","Text":"is num1 equal to num2?"},{"Start":"03:21.905 ","End":"03:27.200","Text":"Does it contain the same value as num2? Let\u0027s see if it does."},{"Start":"03:27.200 ","End":"03:31.220","Text":"I get a response which is a Boolean response."},{"Start":"03:31.220 ","End":"03:35.330","Text":"These operators all return a Boolean response."},{"Start":"03:35.330 ","End":"03:37.160","Text":"In this case, it\u0027s false."},{"Start":"03:37.160 ","End":"03:39.635","Text":"Because num1 contains 7,"},{"Start":"03:39.635 ","End":"03:41.355","Text":"as you\u0027ve seen here,"},{"Start":"03:41.355 ","End":"03:42.990","Text":"and num2 contains 8."},{"Start":"03:42.990 ","End":"03:44.625","Text":"Clearly, they\u0027re not the same."},{"Start":"03:44.625 ","End":"03:49.145","Text":"We would expect therefore the evaluation to return false."},{"Start":"03:49.145 ","End":"03:53.540","Text":"In b2, we\u0027re asked to see if num1 and num2 are not"},{"Start":"03:53.540 ","End":"03:58.175","Text":"equal and just to test that we remember what the operator is."},{"Start":"03:58.175 ","End":"04:01.670","Text":"It is the not sign,"},{"Start":"04:01.670 ","End":"04:05.899","Text":"which is an exclamation mark followed by equals, no spaces."},{"Start":"04:05.899 ","End":"04:10.160","Text":"We\u0027re saying it\u0027s not equal to num2."},{"Start":"04:10.160 ","End":"04:13.985","Text":"As we know, 7 and 8 are not equal."},{"Start":"04:13.985 ","End":"04:18.590","Text":"The expression here generates a result of true,"},{"Start":"04:18.590 ","End":"04:25.670","Text":"num1 not equal to num2 returns the evaluation of true."},{"Start":"04:25.670 ","End":"04:32.224","Text":"In b3, we\u0027re asked to see if num1 is greater than num2."},{"Start":"04:32.224 ","End":"04:36.890","Text":"This is simple case of remembering your greater than and less than symbols."},{"Start":"04:36.890 ","End":"04:40.085","Text":"Num1 is greater than num2."},{"Start":"04:40.085 ","End":"04:41.870","Text":"We know that that\u0027s not true,"},{"Start":"04:41.870 ","End":"04:46.040","Text":"so we expect a false because 7 is not greater than 8."},{"Start":"04:46.040 ","End":"04:48.185","Text":"Let\u0027s try it the other way round then,"},{"Start":"04:48.185 ","End":"04:50.600","Text":"which is b4,"},{"Start":"04:50.600 ","End":"04:53.630","Text":"num1 is less than num2."},{"Start":"04:53.630 ","End":"04:56.030","Text":"Here\u0027s the less than operator."},{"Start":"04:56.030 ","End":"05:00.770","Text":"We would expect that to be true because 7 is less than 8."},{"Start":"05:00.770 ","End":"05:03.080","Text":"We are given a value true,"},{"Start":"05:03.080 ","End":"05:05.075","Text":"which is just what we\u0027d expect."},{"Start":"05:05.075 ","End":"05:12.180","Text":"We\u0027ve used the basic operators now in terms of comparison or relational operators."},{"Start":"05:12.180 ","End":"05:15.000","Text":"They will operate, as you would expect."},{"Start":"05:15.000 ","End":"05:18.695","Text":"Something\u0027s either equal to something else or it\u0027s not equal to something else."},{"Start":"05:18.695 ","End":"05:22.475","Text":"It\u0027s greater than something else or it\u0027s less than something else."},{"Start":"05:22.475 ","End":"05:27.365","Text":"We\u0027re now in part c. We\u0027ve asked to change the value of num2 to 7."},{"Start":"05:27.365 ","End":"05:28.850","Text":"Let\u0027s go ahead and do that."},{"Start":"05:28.850 ","End":"05:32.970","Text":"Remember, num1 is also 7 and then in"},{"Start":"05:32.970 ","End":"05:37.655","Text":"c1 we\u0027ve been asked to test if num1 is greater than or equal to num2."},{"Start":"05:37.655 ","End":"05:43.160","Text":"This is really just so that we get the idea of the greater than or equal to operator,"},{"Start":"05:43.160 ","End":"05:44.780","Text":"which is 2 symbols."},{"Start":"05:44.780 ","End":"05:49.129","Text":"The greater than comes first and the equals comes second."},{"Start":"05:49.129 ","End":"05:55.040","Text":"We\u0027re saying is num1 either greater than or exactly equal to num2."},{"Start":"05:55.040 ","End":"06:00.275","Text":"Of course, it is exactly equal to num2."},{"Start":"06:00.275 ","End":"06:04.785","Text":"Remember before, num1 greater than num2 return to false."},{"Start":"06:04.785 ","End":"06:07.730","Text":"This time because we\u0027ve changed it to greater than or"},{"Start":"06:07.730 ","End":"06:10.955","Text":"equal to and we\u0027ve changed the value of num2 to 7."},{"Start":"06:10.955 ","End":"06:16.009","Text":"We\u0027re getting a true instead of false."},{"Start":"06:16.009 ","End":"06:19.190","Text":"Let\u0027s try it the other way round or not the other way around."},{"Start":"06:19.190 ","End":"06:22.520","Text":"But let\u0027s try the less than or equal to operator,"},{"Start":"06:22.520 ","End":"06:25.055","Text":"which is part c2."},{"Start":"06:25.055 ","End":"06:34.610","Text":"We would expect that also to return true and it does because num1 is not less than num2."},{"Start":"06:34.610 ","End":"06:38.180","Text":"But it is exactly equal to num2 for the same reasons as we said above."},{"Start":"06:38.180 ","End":"06:44.150","Text":"Great. We\u0027ve used all of the basic operators for comparison and relationships."},{"Start":"06:44.150 ","End":"06:51.485","Text":"That\u0027s all straightforward and we\u0027ll see there\u0027s an awful lot in the next topic."},{"Start":"06:51.485 ","End":"06:55.190","Text":"It\u0027s really important that you\u0027ve understood this and by all means,"},{"Start":"06:55.190 ","End":"06:57.710","Text":"spend a little bit of extra time working"},{"Start":"06:57.710 ","End":"07:02.225","Text":"through some of your own examples to just drum that home."},{"Start":"07:02.225 ","End":"07:07.370","Text":"Now, part d, we\u0027ve been asked to assign the value 9 to num3."},{"Start":"07:07.370 ","End":"07:09.430","Text":"Let\u0027s go ahead and do that."},{"Start":"07:09.430 ","End":"07:14.450","Text":"Then use the logical and operator to create a single expression that"},{"Start":"07:14.450 ","End":"07:19.730","Text":"evaluates whether num2 is greater than 5 and less than 10."},{"Start":"07:19.730 ","End":"07:23.720","Text":"You\u0027ll remember that and requires two things to"},{"Start":"07:23.720 ","End":"07:27.920","Text":"be true in order to generate a true result."},{"Start":"07:27.920 ","End":"07:33.290","Text":"What we\u0027ve been asked to do here is num2 greater than 5 and less than 10?"},{"Start":"07:33.290 ","End":"07:34.760","Text":"We\u0027re going to ask two questions."},{"Start":"07:34.760 ","End":"07:38.010","Text":"We\u0027re going to say num2 greater than 5,"},{"Start":"07:38.010 ","End":"07:39.890","Text":"and we\u0027re going to ask another question,"},{"Start":"07:39.890 ","End":"07:44.905","Text":"num2 less than 10."},{"Start":"07:44.905 ","End":"07:48.605","Text":"But what we\u0027re going to do is we have to join those with an and,"},{"Start":"07:48.605 ","End":"07:50.330","Text":"and the keyword is not and."},{"Start":"07:50.330 ","End":"07:53.345","Text":"It would be in Python and Java and C,"},{"Start":"07:53.345 ","End":"07:55.070","Text":"it\u0027s a double ampersand,"},{"Start":"07:55.070 ","End":"07:59.150","Text":"2 ampersands would be a logical and."},{"Start":"07:59.150 ","End":"08:07.110","Text":"As we know, num2 contains 7."},{"Start":"08:07.110 ","End":"08:14.075","Text":"We would expect therefore because num2 is greater than 5 and num2 is less than 10."},{"Start":"08:14.075 ","End":"08:17.150","Text":"Both of those things are true either side of the logical and."},{"Start":"08:17.150 ","End":"08:19.970","Text":"We would expect the result to be true as well."},{"Start":"08:19.970 ","End":"08:24.310","Text":"We do indeed get a value of true."},{"Start":"08:24.310 ","End":"08:26.560","Text":"Now in part f,"},{"Start":"08:26.560 ","End":"08:32.135","Text":"we\u0027ve been asked to change the value of num2 to 5 and run that expression again."},{"Start":"08:32.135 ","End":"08:34.220","Text":"Let\u0027s do that."},{"Start":"08:34.220 ","End":"08:38.300","Text":"num2 equals 5. Let\u0027s run the expression again."},{"Start":"08:38.300 ","End":"08:40.490","Text":"Now this time we get a false."},{"Start":"08:40.490 ","End":"08:42.780","Text":"Exactly the same expression, but we get a false."},{"Start":"08:42.780 ","End":"08:44.750","Text":"I hope you\u0027ll realize why."},{"Start":"08:44.750 ","End":"08:49.340","Text":"It\u0027s because it\u0027s exactly equal to 5 but not greater than 5."},{"Start":"08:49.340 ","End":"08:54.395","Text":"Now num2, this part of the expression would evaluate to false."},{"Start":"08:54.395 ","End":"08:59.105","Text":"This one will be true because 5 is less than 10 still."},{"Start":"08:59.105 ","End":"09:01.670","Text":"But both parts have to be true for"},{"Start":"09:01.670 ","End":"09:05.975","Text":"the overall evaluation to come out true because that\u0027s what and expects."},{"Start":"09:05.975 ","End":"09:10.330","Text":"Hence we\u0027ve got this result of false."},{"Start":"09:10.330 ","End":"09:12.525","Text":"In part g,"},{"Start":"09:12.525 ","End":"09:15.395","Text":"we\u0027ve been asked to use the logical or operator"},{"Start":"09:15.395 ","End":"09:17.870","Text":"to create a single expression that evaluates"},{"Start":"09:17.870 ","End":"09:24.375","Text":"whether num1 is less than num2 or number 3 is equal to 11."},{"Start":"09:24.375 ","End":"09:32.255","Text":"What we want to do here then is say num1 is less than num2."},{"Start":"09:32.255 ","End":"09:37.710","Text":"Then we want the or and we say num3 equals 11."},{"Start":"09:37.710 ","End":"09:42.425","Text":"Now, or in Python is just or but in Java,"},{"Start":"09:42.425 ","End":"09:45.125","Text":"it\u0027s what we call the pipe character and it\u0027s two of them."},{"Start":"09:45.125 ","End":"09:46.850","Text":"It\u0027s like a vertical bar,"},{"Start":"09:46.850 ","End":"09:50.825","Text":"but we need two of those to do a logical or."},{"Start":"09:50.825 ","End":"09:54.680","Text":"What this is doing is it\u0027s joining two expressions together"},{"Start":"09:54.680 ","End":"09:58.730","Text":"and either of them can be true to generate a result of true."},{"Start":"09:58.730 ","End":"10:05.270","Text":"Either num1 is less than num2 or num3 is exactly equal to,"},{"Start":"10:05.270 ","End":"10:08.225","Text":"not 1, I\u0027ve been asked to do 11."},{"Start":"10:08.225 ","End":"10:12.875","Text":"Num3 is exactly equal to 11. Let\u0027s run that."},{"Start":"10:12.875 ","End":"10:20.120","Text":"I get a false because num1 is not less than num2."},{"Start":"10:20.120 ","End":"10:23.585","Text":"If we just remind ourselves what num1 has is 7."},{"Start":"10:23.585 ","End":"10:26.760","Text":"Num2 is 5."},{"Start":"10:26.760 ","End":"10:30.005","Text":"Num1 is actually greater than num2."},{"Start":"10:30.005 ","End":"10:32.374","Text":"Hence this part, it\u0027s going to be false."},{"Start":"10:32.374 ","End":"10:35.410","Text":"Num3 is not 11."},{"Start":"10:35.410 ","End":"10:39.005","Text":"Remind ourselves what num3 contains. It\u0027s got 9."},{"Start":"10:39.005 ","End":"10:41.720","Text":"Neither parts of this expression are true."},{"Start":"10:41.720 ","End":"10:43.550","Text":"That\u0027s false and that\u0027s false."},{"Start":"10:43.550 ","End":"10:47.555","Text":"Therefore, it cannot generate a true value, it generates false."},{"Start":"10:47.555 ","End":"10:50.300","Text":"However, now, if I change the values,"},{"Start":"10:50.300 ","End":"10:56.765","Text":"I\u0027ve been asked in part h of num3 to 11 and run that expression again,"},{"Start":"10:56.765 ","End":"10:59.255","Text":"what I see is true."},{"Start":"10:59.255 ","End":"11:02.330","Text":"Because even though num1 is not"},{"Start":"11:02.330 ","End":"11:05.679","Text":"less than num2 still because we didn\u0027t change their values,"},{"Start":"11:05.679 ","End":"11:08.195","Text":"7 is still not less than 5."},{"Start":"11:08.195 ","End":"11:13.790","Text":"This next part of the expression is num3 equal to 11 is now true."},{"Start":"11:13.790 ","End":"11:17.300","Text":"Only one part of this expression needs to be true with"},{"Start":"11:17.300 ","End":"11:22.175","Text":"all to generate a true as the output."},{"Start":"11:22.175 ","End":"11:26.085","Text":"That\u0027s great, that\u0027s part h done."},{"Start":"11:26.085 ","End":"11:29.510","Text":"In part i, we\u0027ve just been asked to use any combination of"},{"Start":"11:29.510 ","End":"11:32.360","Text":"logical and comparison operators and maybe use"},{"Start":"11:32.360 ","End":"11:36.950","Text":"the not operator as well and brackets to change the order of evaluation."},{"Start":"11:36.950 ","End":"11:38.435","Text":"Do have a play around with that."},{"Start":"11:38.435 ","End":"11:41.030","Text":"I\u0027ll show you an example of what I mean."},{"Start":"11:41.030 ","End":"11:45.825","Text":"For example, I could put a not around the whole thing."},{"Start":"11:45.825 ","End":"11:47.595","Text":"Brackets, first of all,"},{"Start":"11:47.595 ","End":"11:49.680","Text":"all of this will be evaluated."},{"Start":"11:49.680 ","End":"11:51.485","Text":"Whatever the result is."},{"Start":"11:51.485 ","End":"11:54.800","Text":"I will flip the results to the opposite."},{"Start":"11:54.800 ","End":"11:57.065","Text":"You see I was getting true before."},{"Start":"11:57.065 ","End":"11:59.735","Text":"It should flip back to false and it has."},{"Start":"11:59.735 ","End":"12:02.615","Text":"By taking the not out again,"},{"Start":"12:02.615 ","End":"12:04.760","Text":"you\u0027ll see it goes back to true."},{"Start":"12:04.760 ","End":"12:12.045","Text":"Note, the logical not operation just flips the output to the opposite Boolean value."},{"Start":"12:12.045 ","End":"12:13.670","Text":"The brackets, as you see,"},{"Start":"12:13.670 ","End":"12:15.545","Text":"it\u0027s evaluating this whole thing."},{"Start":"12:15.545 ","End":"12:18.335","Text":"Here is one. You can use that in any way you want."},{"Start":"12:18.335 ","End":"12:21.200","Text":"I can have another set of brackets inside the brackets if I wanted to,"},{"Start":"12:21.200 ","End":"12:23.690","Text":"it wouldn\u0027t make any difference in this particular example."},{"Start":"12:23.690 ","End":"12:28.205","Text":"But do have a play around with that and see the effect of brackets"},{"Start":"12:28.205 ","End":"12:33.350","Text":"on the way that things will be evaluated in a logical comparison."},{"Start":"12:33.350 ","End":"12:35.270","Text":"That\u0027s great. In these questions,"},{"Start":"12:35.270 ","End":"12:37.850","Text":"we\u0027ve looked at the logical operators,"},{"Start":"12:37.850 ","End":"12:40.350","Text":"the basic ones were and and or,"},{"Start":"12:40.350 ","End":"12:42.860","Text":"and then we also have not and we also looked at"},{"Start":"12:42.860 ","End":"12:46.475","Text":"the comparison and relational operators of equal to,"},{"Start":"12:46.475 ","End":"12:49.340","Text":"not equal to, greater than, less than,"},{"Start":"12:49.340 ","End":"12:53.690","Text":"and then greater than or equals to and less than or equal to."},{"Start":"12:53.690 ","End":"12:57.600","Text":"I\u0027ll see you in the next exercise."}],"ID":27354},{"Watched":false,"Name":"Exercise 6","Duration":"2m 6s","ChapterTopicVideoID":26445,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.770","Text":"Welcome. In this exercise we\u0027re going to explore the bitwise operators."},{"Start":"00:04.770 ","End":"00:06.540","Text":"In the code pad, as usual,"},{"Start":"00:06.540 ","End":"00:12.465","Text":"we\u0027re going to create a variable using the byte datatype and assign it the value 65."},{"Start":"00:12.465 ","End":"00:13.890","Text":"Then n part b,"},{"Start":"00:13.890 ","End":"00:17.895","Text":"we\u0027re going to perform a bitwise and operation on the variable."},{"Start":"00:17.895 ","End":"00:21.675","Text":"We\u0027re going to use this binary value to do that bitwise."},{"Start":"00:21.675 ","End":"00:26.690","Text":"In part c, we\u0027re asked to explain why you get the resulting value."},{"Start":"00:26.690 ","End":"00:32.525","Text":"In part d, we\u0027re asked to perform a bitwise or operation on the variable,"},{"Start":"00:32.525 ","End":"00:35.990","Text":"but this time using the decimal value 32."},{"Start":"00:35.990 ","End":"00:39.590","Text":"Then again to explain why we get this new value."},{"Start":"00:39.590 ","End":"00:43.970","Text":"In part f, we assign the value 17 to the byte variable,"},{"Start":"00:43.970 ","End":"00:47.450","Text":"then perform a bitwise exclusive or"},{"Start":"00:47.450 ","End":"00:51.920","Text":"operation on the variable using this binary value here."},{"Start":"00:51.920 ","End":"00:55.490","Text":"Once again, we\u0027re asked to explain the resulting evaluation."},{"Start":"00:55.490 ","End":"01:00.065","Text":"Then finally, we assign the value 1 to the byte variable,"},{"Start":"01:00.065 ","End":"01:03.950","Text":"and then perform a complement operation on the variable,"},{"Start":"01:03.950 ","End":"01:08.840","Text":"and we\u0027re asked to explain the value that we get and we\u0027re given a little hint."},{"Start":"01:08.840 ","End":"01:16.730","Text":"We\u0027ll start by creating the variable as he\u0027s asked us in part a. Typing the datatype,"},{"Start":"01:16.730 ","End":"01:18.500","Text":"give it a name,"},{"Start":"01:18.500 ","End":"01:24.340","Text":"and then assign the value 65 as it\u0027s asks us to complete that with a semicolon."},{"Start":"01:24.340 ","End":"01:28.070","Text":"Now in part b, we\u0027ve been asked to perform a bitwise and"},{"Start":"01:28.070 ","End":"01:32.225","Text":"operation on the variable using the given value."},{"Start":"01:32.225 ","End":"01:39.710","Text":"A variable name comes first the bitwise and operation is a single ampersand symbol."},{"Start":"01:39.710 ","End":"01:44.430","Text":"The value we\u0027ve been asked to and width is 0b01000000."},{"Start":"01:46.850 ","End":"01:49.715","Text":"Lets go and see what that does."},{"Start":"01:49.715 ","End":"01:53.135","Text":"The value we get back is 64."},{"Start":"01:53.135 ","End":"01:56.510","Text":"As we know with an and we have to have a"},{"Start":"01:56.510 ","End":"02:01.909","Text":"1 in both bytes in order to get a 1 at the output."},{"Start":"02:01.909 ","End":"02:04.640","Text":"Maybe it\u0027s easier to see this if we have two literals."},{"Start":"02:04.640 ","End":"02:10.745","Text":"If I put 0b01000000 as we\u0027ve started with,"},{"Start":"02:10.745 ","End":"02:15.770","Text":"and the value that we\u0027re ending with is 65,"},{"Start":"02:15.770 ","End":"02:19.255","Text":"which is actually a same bit pattern,"},{"Start":"02:19.255 ","End":"02:21.500","Text":"but with a 1 at the end."},{"Start":"02:21.500 ","End":"02:23.150","Text":"If we add those together,"},{"Start":"02:23.150 ","End":"02:26.570","Text":"we should get the same results, and we do."},{"Start":"02:26.570 ","End":"02:31.250","Text":"It\u0027s much easier to see obviously with the binary representation because"},{"Start":"02:31.250 ","End":"02:36.730","Text":"65 here has a 1 and 64 only has a 1."},{"Start":"02:36.730 ","End":"02:39.470","Text":"Therefore, the output is also going to be"},{"Start":"02:39.470 ","End":"02:42.730","Text":"64 because the only places where there are 2 1s,"},{"Start":"02:42.730 ","End":"02:45.465","Text":"are these 2 bit positions here."},{"Start":"02:45.465 ","End":"02:49.550","Text":"That explains and the value we get from parts a and b,"},{"Start":"02:49.550 ","End":"02:51.545","Text":"so part c is done."},{"Start":"02:51.545 ","End":"02:54.260","Text":"Now we are asked to perform a bitwise or"},{"Start":"02:54.260 ","End":"02:57.470","Text":"operation on the same variable with the same content Susan,"},{"Start":"02:57.470 ","End":"02:59.455","Text":"the decimal value 32."},{"Start":"02:59.455 ","End":"03:03.280","Text":"This just involves us using again a variable name,"},{"Start":"03:03.280 ","End":"03:09.395","Text":"and this time the bitwise or operation is the vertical bar or pipe character,"},{"Start":"03:09.395 ","End":"03:11.120","Text":"and only one of those is needed."},{"Start":"03:11.120 ","End":"03:13.385","Text":"A logical order would have two of them"},{"Start":"03:13.385 ","End":"03:16.930","Text":"because this is a bit wise or we only need one of them."},{"Start":"03:16.930 ","End":"03:19.850","Text":"Then we\u0027ve been asked to use the value 32."},{"Start":"03:19.850 ","End":"03:22.475","Text":"What\u0027s the value we get back?"},{"Start":"03:22.475 ","End":"03:25.760","Text":"We get 97 this time."},{"Start":"03:25.760 ","End":"03:31.940","Text":"Let\u0027s try and explain that value is it\u0027s asked us to in part e. Well,"},{"Start":"03:31.940 ","End":"03:34.700","Text":"if we do the same thing again and go from"},{"Start":"03:34.700 ","End":"03:38.345","Text":"the binary versions and the binary representations."},{"Start":"03:38.345 ","End":"03:43.460","Text":"We know already that 65 is 0b01000001"},{"Start":"03:43.460 ","End":"03:50.590","Text":", so that\u0027s 65."},{"Start":"03:50.590 ","End":"03:56.090","Text":"If we do a bit wise or with 32 is represented"},{"Start":"03:56.090 ","End":"04:01.545","Text":"by 0b00100000,or the first bit there will be 1 to 8,"},{"Start":"04:01.545 ","End":"04:04.995","Text":"then 64, then 32 there."},{"Start":"04:04.995 ","End":"04:08.685","Text":"Then all the other 4 bits will be 0s."},{"Start":"04:08.685 ","End":"04:12.570","Text":"Let\u0027s see what we get there and we do indeed get 97."},{"Start":"04:12.570 ","End":"04:16.865","Text":"We can see again more clearly when we do it with binary values"},{"Start":"04:16.865 ","End":"04:22.025","Text":"that the bitwise or will take each individual bit and,"},{"Start":"04:22.025 ","End":"04:26.010","Text":"or a bit in the respective position."},{"Start":"04:26.110 ","End":"04:31.715","Text":"Here, because we\u0027ve got an extra bit being set here,"},{"Start":"04:31.715 ","End":"04:35.410","Text":"the result will also have an extra bit set."},{"Start":"04:35.410 ","End":"04:37.115","Text":"It will be set here,"},{"Start":"04:37.115 ","End":"04:43.730","Text":"and the result. We\u0027ll have 01100001."},{"Start":"04:43.730 ","End":"04:49.805","Text":"If we want to prove that to send a look at the value of 97 in binary"},{"Start":"04:49.805 ","End":"04:58.590","Text":"should be 01100001 if we\u0027ve assumed,"},{"Start":"04:58.590 ","End":"04:59.910","Text":"right and it is."},{"Start":"04:59.910 ","End":"05:01.800","Text":"You can see that very clearly,"},{"Start":"05:01.800 ","End":"05:03.260","Text":"got a 1 set there,"},{"Start":"05:03.260 ","End":"05:05.540","Text":"but we\u0027ve also got at 1 set there,"},{"Start":"05:05.540 ","End":"05:08.195","Text":"which is what we see appearing here."},{"Start":"05:08.195 ","End":"05:13.520","Text":"The rest of it is all 0s apart from this bit here, which has a1."},{"Start":"05:13.520 ","End":"05:20.224","Text":"That explains part e. Moving on to part f,"},{"Start":"05:20.224 ","End":"05:23.675","Text":"we assign the value 17 to the variables."},{"Start":"05:23.675 ","End":"05:25.580","Text":"Let\u0027s go ahead and do that."},{"Start":"05:25.580 ","End":"05:28.280","Text":"Now we\u0027ve got 17 decimal in there."},{"Start":"05:28.280 ","End":"05:32.375","Text":"Now we\u0027ve been asked to perform a bitwise exclusive or"},{"Start":"05:32.375 ","End":"05:37.040","Text":"operation on that variable using a given binary value."},{"Start":"05:37.040 ","End":"05:42.425","Text":"Bitwise exclusive or we don\u0027t see a logical equivalent,"},{"Start":"05:42.425 ","End":"05:46.745","Text":"but that\u0027s the symbol for the operator to do a bitwise exclusive"},{"Start":"05:46.745 ","End":"05:51.230","Text":"or remember exclusive or means, not both bits."},{"Start":"05:51.230 ","End":"05:58.190","Text":"If 2 bits are set to operate in the 2 data items that were exclusive oriented together,"},{"Start":"05:58.190 ","End":"06:04.655","Text":"we ignore that bit once only one of them to have a 1 at the output."},{"Start":"06:04.655 ","End":"06:09.450","Text":"The value had been asked to put in 0b00010001."},{"Start":"06:12.670 ","End":"06:16.860","Text":"Let us see what result we get,"},{"Start":"06:16.860 ","End":"06:19.730","Text":"and 0 shortly, There we go."},{"Start":"06:19.730 ","End":"06:22.805","Text":"The result I get is 0."},{"Start":"06:22.805 ","End":"06:25.550","Text":"Now why do I get 0?"},{"Start":"06:25.550 ","End":"06:27.710","Text":"Well, the reason is,"},{"Start":"06:27.710 ","End":"06:31.025","Text":"if we were to put this again in binary,"},{"Start":"06:31.025 ","End":"06:35.435","Text":"actually what we\u0027ll find is the binary value that we were"},{"Start":"06:35.435 ","End":"06:40.655","Text":"oring with exclusive or in width is actually 17."},{"Start":"06:40.655 ","End":"06:46.010","Text":"We were doing 17 and exclusive oring with 17."},{"Start":"06:46.010 ","End":"06:54.229","Text":"Because both of these patterns have 1s in exactly the same place and nowhere else,"},{"Start":"06:54.229 ","End":"06:59.440","Text":"the result is going to be 0 and hopefully you can see that."},{"Start":"06:59.440 ","End":"07:04.700","Text":"Let\u0027s just prove that we\u0027ve got a 1 in this position and in"},{"Start":"07:04.700 ","End":"07:06.830","Text":"this position and we\u0027ve got a 1 in this position and"},{"Start":"07:06.830 ","End":"07:09.290","Text":"that position of course we have because they have the same number,"},{"Start":"07:09.290 ","End":"07:13.055","Text":"although we didn\u0027t make that obvious by putting it in decimal initially."},{"Start":"07:13.055 ","End":"07:18.440","Text":"The reason the output is 0 is because there is nowhere in either of these"},{"Start":"07:18.440 ","End":"07:23.810","Text":"2 where there is a 1 and it isn\u0027t already present in the other side."},{"Start":"07:23.810 ","End":"07:29.915","Text":"Hence, we get the result of 0 and that\u0027s why exclusive or is doing its job."},{"Start":"07:29.915 ","End":"07:32.359","Text":"It\u0027s only putting a 1 at the output."},{"Start":"07:32.359 ","End":"07:37.050","Text":"If the relative position doesn\u0027t have 2 1s."},{"Start":"07:37.050 ","End":"07:38.445","Text":"If there\u0027s a single 1,"},{"Start":"07:38.445 ","End":"07:40.245","Text":"then the output will have a 1."},{"Start":"07:40.245 ","End":"07:41.600","Text":"There\u0027s 2 0s,"},{"Start":"07:41.600 ","End":"07:43.535","Text":"then obviously it will have a 0 there."},{"Start":"07:43.535 ","End":"07:45.875","Text":"Let\u0027s do the last part,"},{"Start":"07:45.875 ","End":"07:53.535","Text":"which is part h. We\u0027ve been told to assign the value 1 to the variable,"},{"Start":"07:53.535 ","End":"07:56.075","Text":"and then to perform a complement."},{"Start":"07:56.075 ","End":"07:58.880","Text":"A complement operator is different than the one\u0027s we\u0027ve"},{"Start":"07:58.880 ","End":"08:01.805","Text":"just been using because it\u0027s what\u0027s called a unitary operator,"},{"Start":"08:01.805 ","End":"08:05.435","Text":"only needs 1 thing to operate on."},{"Start":"08:05.435 ","End":"08:09.650","Text":"The symbol itself is a tilde character."},{"Start":"08:09.650 ","End":"08:12.320","Text":"It\u0027s quite tricky to find on keyboards often,"},{"Start":"08:12.320 ","End":"08:16.250","Text":"minds next to the Enter key above the hash."},{"Start":"08:16.250 ","End":"08:18.035","Text":"It could be anywhere on your keyboard,"},{"Start":"08:18.035 ","End":"08:22.445","Text":"but it\u0027s usually in a fairly hard to find positions is not typed very often."},{"Start":"08:22.445 ","End":"08:26.540","Text":"That\u0027s the tilde character and that\u0027s what does the complement."},{"Start":"08:26.540 ","End":"08:29.300","Text":"We simply put the name of our variable and we\u0027ll"},{"Start":"08:29.300 ","End":"08:32.510","Text":"get a compliment of the value that\u0027s in the variable."},{"Start":"08:32.510 ","End":"08:34.265","Text":"I get -2,"},{"Start":"08:34.265 ","End":"08:36.575","Text":"now note I get int back."},{"Start":"08:36.575 ","End":"08:39.965","Text":"I really should be looking to get a bite back."},{"Start":"08:39.965 ","End":"08:42.920","Text":"I could do cast on this to see the result."},{"Start":"08:42.920 ","End":"08:46.880","Text":"But let\u0027s have a look at why it\u0027s -2. first of all,"},{"Start":"08:46.880 ","End":"08:49.940","Text":"because it\u0027s a signed number."},{"Start":"08:49.940 ","End":"08:53.930","Text":"If I were to do this as a byte literal,"},{"Start":"08:53.930 ","End":"08:59.610","Text":"I\u0027d get 1 is obviously all 0s in the upper level and"},{"Start":"08:59.610 ","End":"09:06.005","Text":"then 0001 that is 1 in binary."},{"Start":"09:06.005 ","End":"09:08.345","Text":"Now if I was to do a complement,"},{"Start":"09:08.345 ","End":"09:14.270","Text":"remember the complement turns every single bit to the opposite of what it currently is."},{"Start":"09:14.270 ","End":"09:21.895","Text":"All of these would be a 1 and this would be a 0."},{"Start":"09:21.895 ","End":"09:24.620","Text":"That\u0027s what the complement operation is doing."},{"Start":"09:24.620 ","End":"09:27.155","Text":"If you look at that again,"},{"Start":"09:27.155 ","End":"09:35.700","Text":"and if I actually type this out and flip it manually, 11111110."},{"Start":"09:35.810 ","End":"09:40.280","Text":"This is what the complemented version of that would look like."},{"Start":"09:40.280 ","End":"09:41.890","Text":"What\u0027s the value I get?"},{"Start":"09:41.890 ","End":"09:48.095","Text":"It\u0027s -2,and the only reason I\u0027m having to bite in front of it is when I put literals in,"},{"Start":"09:48.095 ","End":"09:51.020","Text":"in blue jay, it will assume they\u0027re integers always."},{"Start":"09:51.020 ","End":"09:53.990","Text":"A sign bit will be way over here"},{"Start":"09:53.990 ","End":"09:57.800","Text":"somewhere because it\u0027s a 32-bit number, obviously an integer."},{"Start":"09:57.800 ","End":"10:05.105","Text":"That\u0027s the explanation for part h. We get -2 because we\u0027ve complemented this pattern"},{"Start":"10:05.105 ","End":"10:08.750","Text":"when we\u0027re complimenting a bite that contains 1"},{"Start":"10:08.750 ","End":"10:12.455","Text":"and the complement will return this value here,"},{"Start":"10:12.455 ","End":"10:15.250","Text":"which I\u0027ve typed out as binary search easier for you to see,"},{"Start":"10:15.250 ","End":"10:16.880","Text":"and that binary value,"},{"Start":"10:16.880 ","End":"10:19.925","Text":"if it\u0027s a byte, is worth -2."},{"Start":"10:19.925 ","End":"10:23.580","Text":"That\u0027s it for this one. I\u0027ll see you in the next one."}],"ID":27355},{"Watched":false,"Name":"Exercise 7","Duration":"6m 1s","ChapterTopicVideoID":26446,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.910","Text":"Hi, again. In this video we\u0027re going to look at"},{"Start":"00:02.910 ","End":"00:05.550","Text":"the exercise in which we explore the increment,"},{"Start":"00:05.550 ","End":"00:08.880","Text":"decrement, and compound assignment operators."},{"Start":"00:08.880 ","End":"00:12.630","Text":"We have first been asked to create a variable of int datatype,"},{"Start":"00:12.630 ","End":"00:15.810","Text":"and to assign to it the initial value 10 decimal."},{"Start":"00:15.810 ","End":"00:20.070","Text":"In part a then, we\u0027re asked to use the post increment operator"},{"Start":"00:20.070 ","End":"00:23.910","Text":"on the variable and to not put a semicolon on the end of the line."},{"Start":"00:23.910 ","End":"00:26.160","Text":"In part b, we\u0027re asked the question,"},{"Start":"00:26.160 ","End":"00:31.290","Text":"why does that value reflected back by Bluej not appear to change?"},{"Start":"00:31.290 ","End":"00:33.450","Text":"Then we use in Part C,"},{"Start":"00:33.450 ","End":"00:36.615","Text":"the pre increment operator on the same variable."},{"Start":"00:36.615 ","End":"00:40.770","Text":"Once again, not to put a semicolon on the end of the line."},{"Start":"00:40.770 ","End":"00:42.500","Text":"In Part d,"},{"Start":"00:42.500 ","End":"00:47.990","Text":"we\u0027re asked what difference we observe between post and pre increment."},{"Start":"00:47.990 ","End":"00:50.330","Text":"Moving on to part e,"},{"Start":"00:50.330 ","End":"00:55.575","Text":"we are using now the pre decrement operator on the variable."},{"Start":"00:55.575 ","End":"01:00.110","Text":"In part f, we use the post decrement operator on the variable."},{"Start":"01:00.110 ","End":"01:03.980","Text":"Then, we use a compound assignment to multiply the variable"},{"Start":"01:03.980 ","End":"01:08.355","Text":"by 10 and store the result back into the variable."},{"Start":"01:08.355 ","End":"01:11.630","Text":"In part h, we use another compound assignment to"},{"Start":"01:11.630 ","End":"01:15.175","Text":"add 28 to the variable and store the result back in."},{"Start":"01:15.175 ","End":"01:17.260","Text":"Finally in part i,"},{"Start":"01:17.260 ","End":"01:25.150","Text":"we\u0027re asked to use a compound assignment to do a bitwise exclusive or with a value 129."},{"Start":"01:25.150 ","End":"01:30.875","Text":"We\u0027ve been first starts to create a variable of int datatype."},{"Start":"01:30.875 ","End":"01:33.870","Text":"Let\u0027s go ahead and do that."},{"Start":"01:34.460 ","End":"01:41.405","Text":"We are asked to give it the initial value of 10 in decimal."},{"Start":"01:41.405 ","End":"01:44.060","Text":"Then in part a, we\u0027re asked to use"},{"Start":"01:44.060 ","End":"01:46.320","Text":"the post increment operator on"},{"Start":"01:46.320 ","End":"01:49.505","Text":"the variable and to not put a semicolon on the end of the line."},{"Start":"01:49.505 ","End":"01:52.195","Text":"We get a value straight back."},{"Start":"01:52.195 ","End":"01:56.390","Text":"The increment and decrement operators are unitary."},{"Start":"01:56.390 ","End":"01:58.895","Text":"Once again, they only need one thing to operate on."},{"Start":"01:58.895 ","End":"02:01.160","Text":"If it\u0027s a post increment operator,"},{"Start":"02:01.160 ","End":"02:03.365","Text":"it follows the name of the variable."},{"Start":"02:03.365 ","End":"02:08.835","Text":"We\u0027ll put myVar, and then two pluses that will increment myVar by one."},{"Start":"02:08.835 ","End":"02:10.980","Text":"Let\u0027s see the value."},{"Start":"02:10.980 ","End":"02:14.205","Text":"Now, I had 10 in there originally."},{"Start":"02:14.205 ","End":"02:19.580","Text":"It does not seem to have changed as part b seems to suggest."},{"Start":"02:19.580 ","End":"02:23.400","Text":"It\u0027s asking, why it doesn\u0027t appear to change?"},{"Start":"02:23.400 ","End":"02:24.890","Text":"There is a clue there,"},{"Start":"02:24.890 ","End":"02:26.540","Text":"and it says appear to change."},{"Start":"02:26.540 ","End":"02:30.405","Text":"The value reflected back was 10."},{"Start":"02:30.405 ","End":"02:32.764","Text":"But what does myVar actually contain?"},{"Start":"02:32.764 ","End":"02:35.660","Text":"It actually contains 11."},{"Start":"02:35.660 ","End":"02:38.750","Text":"What we\u0027re seeing here is the difference between the post increment"},{"Start":"02:38.750 ","End":"02:42.215","Text":"and a pre increment when it\u0027s used in an expression."},{"Start":"02:42.215 ","End":"02:43.910","Text":"Although it doesn\u0027t look like it,"},{"Start":"02:43.910 ","End":"02:49.010","Text":"this is an expression and could be used in an expression if we wanted it to"},{"Start":"02:49.010 ","End":"02:54.950","Text":"but what it\u0027s doing is it\u0027s giving us the value back before it increments it."},{"Start":"02:54.950 ","End":"03:00.015","Text":"Hence, the name post increment because it will return a value."},{"Start":"03:00.015 ","End":"03:04.490","Text":"Then after post the return of the value, equal increment it."},{"Start":"03:04.490 ","End":"03:06.260","Text":"That\u0027s exactly what\u0027s happened here."},{"Start":"03:06.260 ","End":"03:07.595","Text":"We started with 10,"},{"Start":"03:07.595 ","End":"03:09.170","Text":"myVar had 10 in it,"},{"Start":"03:09.170 ","End":"03:11.975","Text":"and when we executed myVar plus, plus."},{"Start":"03:11.975 ","End":"03:16.325","Text":"It gave us back the value before the increment,"},{"Start":"03:16.325 ","End":"03:19.715","Text":"which we see here, but when we display the value,"},{"Start":"03:19.715 ","End":"03:23.820","Text":"we\u0027ve seen them, it\u0027s actually got 11 and then now."},{"Start":"03:23.820 ","End":"03:27.320","Text":"Let\u0027s see it should be fairly obvious what happens in part"},{"Start":"03:27.320 ","End":"03:32.030","Text":"c. Use the pre increment operator on the variable,"},{"Start":"03:32.030 ","End":"03:35.010","Text":"and don\u0027t put a semicolon on the end."},{"Start":"03:35.010 ","End":"03:36.829","Text":"We see the value back straightaway."},{"Start":"03:36.829 ","End":"03:39.170","Text":"If I do plus plus MyVar,"},{"Start":"03:39.170 ","End":"03:41.525","Text":"that\u0027s the pre increment."},{"Start":"03:41.525 ","End":"03:44.150","Text":"Increment because it\u0027s plus, double plus,"},{"Start":"03:44.150 ","End":"03:48.095","Text":"and pre because it comes before the variable name."},{"Start":"03:48.095 ","End":"03:52.850","Text":"It reflects back the value straight away in the expression."},{"Start":"03:52.850 ","End":"03:56.000","Text":"Obviously, there\u0027s no other parts to this expression here."},{"Start":"03:56.000 ","End":"04:00.250","Text":"But it\u0027s giving me the value back straightaway of the incremented value."},{"Start":"04:00.250 ","End":"04:03.845","Text":"It was 11, and it immediately gives me 12 back."},{"Start":"04:03.845 ","End":"04:07.340","Text":"It shows me the value 12,"},{"Start":"04:07.340 ","End":"04:11.495","Text":"and it\u0027s also got stored in it 12, you\u0027ll find there."},{"Start":"04:11.495 ","End":"04:17.145","Text":"You see the contrast now between the post increment and the pre increment."},{"Start":"04:17.145 ","End":"04:20.325","Text":"Basically, they both add 1 but 1,"},{"Start":"04:20.325 ","End":"04:25.130","Text":"if it\u0027s involved in expression will return the value before it\u0027s incremented."},{"Start":"04:25.130 ","End":"04:28.805","Text":"The other one will show you the increments straight away,"},{"Start":"04:28.805 ","End":"04:32.225","Text":"as we see in these examples here."},{"Start":"04:32.225 ","End":"04:40.010","Text":"That\u0027s us done from parts a to d. Now we\u0027ve been asked to use the pre decrement operator."},{"Start":"04:40.010 ","End":"04:43.560","Text":"Presumably, that is going to be straightforward,"},{"Start":"04:43.560 ","End":"04:45.165","Text":"and follow the same pattern."},{"Start":"04:45.165 ","End":"04:50.625","Text":"Pre decrement, decrement is minus minus."},{"Start":"04:50.625 ","End":"04:53.140","Text":"This is pre decrement."},{"Start":"04:53.140 ","End":"04:56.630","Text":"It\u0027s going to give me the value back straight away when I get it"},{"Start":"04:56.630 ","End":"05:00.285","Text":"reflected back because it\u0027s used in an expression here and it\u0027s 11."},{"Start":"05:00.285 ","End":"05:01.430","Text":"Which is what I expect,"},{"Start":"05:01.430 ","End":"05:04.605","Text":"and it will contain 11, which it does."},{"Start":"05:04.605 ","End":"05:08.840","Text":"Now I\u0027m asked to use the post decrement operator."},{"Start":"05:08.840 ","End":"05:14.360","Text":"With F^F, that\u0027ll be myVar minus, minus."},{"Start":"05:14.360 ","End":"05:16.760","Text":"What do you expect to happen here?"},{"Start":"05:16.760 ","End":"05:18.800","Text":"Because it\u0027s a post decrement,"},{"Start":"05:18.800 ","End":"05:22.310","Text":"we should see 11 reflected back because that\u0027s"},{"Start":"05:22.310 ","End":"05:26.600","Text":"the value that we expect before we take away 1."},{"Start":"05:26.600 ","End":"05:29.520","Text":"But it then should subsequently contain 10."},{"Start":"05:29.520 ","End":"05:32.790","Text":"We do indeed see 11 reflected back."},{"Start":"05:32.790 ","End":"05:35.040","Text":"If we look at myVar,"},{"Start":"05:35.040 ","End":"05:38.070","Text":"it does indeed contain 10."},{"Start":"05:38.070 ","End":"05:41.990","Text":"That\u0027s us done from parts a to f. Now"},{"Start":"05:41.990 ","End":"05:47.330","Text":"the last couple of parts to this exercise asks us to do some compound assignments."},{"Start":"05:47.330 ","End":"05:52.340","Text":"In part g says user compound assignment to multiply the variable by 10,"},{"Start":"05:52.340 ","End":"05:54.955","Text":"and store the result back into the variable."},{"Start":"05:54.955 ","End":"06:00.065","Text":"Well at compound assignment is a very lean syntax."},{"Start":"06:00.065 ","End":"06:03.200","Text":"What it will do is do some operation,"},{"Start":"06:03.200 ","End":"06:08.300","Text":"and store immediately back the value into the variable."},{"Start":"06:08.300 ","End":"06:14.215","Text":"What we want to do is say, myVar times equals 10."},{"Start":"06:14.215 ","End":"06:17.910","Text":"What we\u0027re saying, is multiplied by 10,"},{"Start":"06:17.910 ","End":"06:21.220","Text":"and store it back into myVar."},{"Start":"06:21.220 ","End":"06:29.470","Text":"We should see a 100 stored back into myVar if we\u0027ve got the syntax right, and we do."},{"Start":"06:29.470 ","End":"06:32.960","Text":"It\u0027s not just reflecting back the current value of myVar,"},{"Start":"06:32.960 ","End":"06:35.330","Text":"it\u0027s actually stored that in MyVar as well."},{"Start":"06:35.330 ","End":"06:37.055","Text":"Just to prove it, I\u0027ll do that."},{"Start":"06:37.055 ","End":"06:43.660","Text":"The expression results in 10 being multiplied by 10 because that\u0027s what myVar had in it,"},{"Start":"06:43.660 ","End":"06:45.590","Text":"and that\u0027s what we see reflected back here."},{"Start":"06:45.590 ","End":"06:51.650","Text":"But it also results in the assignment of a new value to myVar."},{"Start":"06:51.650 ","End":"06:54.320","Text":"We\u0027re doing two things that we\u0027re doing a multiplication,"},{"Start":"06:54.320 ","End":"06:57.635","Text":"and then we\u0027re storing it back into the original variables."},{"Start":"06:57.635 ","End":"07:01.880","Text":"The equivalent way of doing this in slightly longer syntax would"},{"Start":"07:01.880 ","End":"07:05.900","Text":"have been this myVar equals myVar times 10 would have"},{"Start":"07:05.900 ","End":"07:07.880","Text":"had exactly the same result but it\u0027s"},{"Start":"07:07.880 ","End":"07:13.985","Text":"a slightly more compact form to do it with the compound assignment."},{"Start":"07:13.985 ","End":"07:16.820","Text":"That\u0027s part g. Now it\u0027s saying use"},{"Start":"07:16.820 ","End":"07:21.035","Text":"a compound assignment to add 28 to the variable and store the results."},{"Start":"07:21.035 ","End":"07:22.760","Text":"That\u0027s exactly the same."},{"Start":"07:22.760 ","End":"07:25.655","Text":"We just obviously going to use a different symbol."},{"Start":"07:25.655 ","End":"07:27.950","Text":"A plus comes first,"},{"Start":"07:27.950 ","End":"07:31.520","Text":"then the equals, and then whatever the value is,"},{"Start":"07:31.520 ","End":"07:33.365","Text":"what we want to work with."},{"Start":"07:33.365 ","End":"07:39.080","Text":"It\u0027s added 28 to what was already in there and stored it back into myVar."},{"Start":"07:39.080 ","End":"07:43.815","Text":"Myvar contains 128, nice and easy."},{"Start":"07:43.815 ","End":"07:46.940","Text":"Then the last one is to use a compound assignment to do"},{"Start":"07:46.940 ","End":"07:50.315","Text":"a bitwise exclusive or with your variable,"},{"Start":"07:50.315 ","End":"07:51.668","Text":"and the value 1, 2,"},{"Start":"07:51.668 ","End":"07:53.880","Text":"9, install them only back."},{"Start":"07:53.880 ","End":"08:02.340","Text":"That is going to be myVar bitwise exclusive or is the current symbols,"},{"Start":"08:02.340 ","End":"08:05.734","Text":"is usually shift, and, followed by equals."},{"Start":"08:05.734 ","End":"08:06.980","Text":"We just did that on its own."},{"Start":"08:06.980 ","End":"08:11.015","Text":"It would do the bitwise exclusive or but it wouldn\u0027t store it back into myVar."},{"Start":"08:11.015 ","End":"08:15.485","Text":"We put the equals to store it back into myVar."},{"Start":"08:15.485 ","End":"08:18.432","Text":"Then we will use the value 1,"},{"Start":"08:18.432 ","End":"08:20.520","Text":"2, 9, and see what we get back."},{"Start":"08:20.520 ","End":"08:22.095","Text":"We get 1 back."},{"Start":"08:22.095 ","End":"08:25.725","Text":"Because remember the bitwise exclusive or,"},{"Start":"08:25.725 ","End":"08:29.415","Text":"doesn\u0027t want to see two 1s\u0027 in any bit position,"},{"Start":"08:29.415 ","End":"08:30.942","Text":"1, 2, 8, and 1, 2,"},{"Start":"08:30.942 ","End":"08:36.500","Text":"9 are exactly the same number with the least significant bit set in 1, 2, 9."},{"Start":"08:36.500 ","End":"08:39.845","Text":"It\u0027s the same as doing this, for example."},{"Start":"08:39.845 ","End":"08:42.105","Text":"This will be 1, 2, 8."},{"Start":"08:42.105 ","End":"08:46.220","Text":"If we do a bitwise exclusive or,"},{"Start":"08:46.220 ","End":"08:47.720","Text":"with 1, 2, 9,"},{"Start":"08:47.720 ","End":"08:50.705","Text":"it\u0027ll learn this. Hence, we get 1."},{"Start":"08:50.705 ","End":"08:54.749","Text":"Because we did an compound assignment,"},{"Start":"08:54.749 ","End":"08:56.940","Text":"that value in myVar will now be stored away."},{"Start":"08:56.940 ","End":"08:58.695","Text":"MyVar will contain 1."},{"Start":"08:58.695 ","End":"09:01.305","Text":"That\u0027s it for Exercise 7."},{"Start":"09:01.305 ","End":"09:03.940","Text":"I\u0027ll see you in the next one."}],"ID":27356},{"Watched":false,"Name":"Exercise 8","Duration":"4m 17s","ChapterTopicVideoID":26929,"CourseChapterTopicPlaylistID":246358,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.940","Text":"Hey, welcome back. In this final exercise,"},{"Start":"00:02.940 ","End":"00:05.340","Text":"we\u0027re going to move away from the code pad and"},{"Start":"00:05.340 ","End":"00:08.520","Text":"instead create a program in the BlueJ editor."},{"Start":"00:08.520 ","End":"00:12.090","Text":"We\u0027ve eventually been asked to create a class in this project that we\u0027ve already"},{"Start":"00:12.090 ","End":"00:15.480","Text":"been working in code MyTempConverterApp."},{"Start":"00:15.480 ","End":"00:19.740","Text":"Then in Part A to declare a variable of an appropriate type to hold"},{"Start":"00:19.740 ","End":"00:27.600","Text":"an input temperature and to give it an initial value of 37.77778."},{"Start":"00:27.600 ","End":"00:30.750","Text":"Then in Part B, to declare a variable of an appropriate type,"},{"Start":"00:30.750 ","End":"00:33.615","Text":"again, to hold an output temperature."},{"Start":"00:33.615 ","End":"00:38.770","Text":"Then in Part C, we\u0027re asked to create a method inside the class called Convert."},{"Start":"00:38.770 ","End":"00:41.660","Text":"Then in Part D, within the Convert method,"},{"Start":"00:41.660 ","End":"00:44.540","Text":"we are asked to add a line that uses whatever operators are"},{"Start":"00:44.540 ","End":"00:47.720","Text":"needed to convert the input temperature from"},{"Start":"00:47.720 ","End":"00:51.050","Text":"Celsius to Fahrenheit and to assign"},{"Start":"00:51.050 ","End":"00:54.855","Text":"the evaluated value to the output temperature variable."},{"Start":"00:54.855 ","End":"00:56.335","Text":"Then in Part E,"},{"Start":"00:56.335 ","End":"00:59.390","Text":"we\u0027re asked to add a second line in that method which will print"},{"Start":"00:59.390 ","End":"01:03.700","Text":"the output temperature to the screen using system out print line."},{"Start":"01:03.700 ","End":"01:06.830","Text":"Then in Part F, we are asked to compile the program and test"},{"Start":"01:06.830 ","End":"01:10.324","Text":"it correct any errors that have been signaled by the compiler."},{"Start":"01:10.324 ","End":"01:16.010","Text":"In Part G, create an object from the class to finally test the code and"},{"Start":"01:16.010 ","End":"01:22.375","Text":"run the Convert method in Part H and check that the result is a 100."},{"Start":"01:22.375 ","End":"01:28.265","Text":"The first thing we need to do is to create a class within our project."},{"Start":"01:28.265 ","End":"01:30.530","Text":"Up until now, we\u0027ve been using the codePad for everything."},{"Start":"01:30.530 ","End":"01:33.410","Text":"Generally, you would have a project which will contain"},{"Start":"01:33.410 ","End":"01:36.470","Text":"all your code and that will be made up of multiple classes,"},{"Start":"01:36.470 ","End":"01:38.720","Text":"which will appear here in this exercise."},{"Start":"01:38.720 ","End":"01:42.980","Text":"We only need 1 class and we\u0027ll do for many of the initial exercises."},{"Start":"01:42.980 ","End":"01:46.190","Text":"Let\u0027s go ahead and create the new class by clicking on the button"},{"Start":"01:46.190 ","End":"01:50.630","Text":"here and giving it the name we\u0027ve been asked to give,"},{"Start":"01:50.630 ","End":"01:58.235","Text":"which is MyTempConverterApp that we are given"},{"Start":"01:58.235 ","End":"02:02.750","Text":"the class and we will have code in which BlueJ just helpfully"},{"Start":"02:02.750 ","End":"02:07.545","Text":"puts in for you while I wanted to take it out just to make it clear what we\u0027re adding."},{"Start":"02:07.545 ","End":"02:11.405","Text":"We\u0027ll just keep the opening line and the braces."},{"Start":"02:11.405 ","End":"02:14.720","Text":"In Part A, we\u0027ve been asked to declare a variable of"},{"Start":"02:14.720 ","End":"02:19.100","Text":"an appropriate type to hold an input temperature and to give it an initial value."},{"Start":"02:19.100 ","End":"02:22.370","Text":"37 point several 7, and an 8."},{"Start":"02:22.370 ","End":"02:26.740","Text":"What would be an appropriate data type for this data?"},{"Start":"02:26.740 ","End":"02:29.255","Text":"Well, it\u0027s a real number,"},{"Start":"02:29.255 ","End":"02:31.625","Text":"so our choice is a float or a double."},{"Start":"02:31.625 ","End":"02:35.270","Text":"Double would probably be overkill for this number."},{"Start":"02:35.270 ","End":"02:37.940","Text":"There\u0027s not many digits in the decimal places,"},{"Start":"02:37.940 ","End":"02:40.560","Text":"so float will suffice."},{"Start":"02:40.560 ","End":"02:42.560","Text":"If we put the data type float,"},{"Start":"02:42.560 ","End":"02:47.225","Text":"give it a name I\u0027m going to call mine input t rather than writing out temperature."},{"Start":"02:47.225 ","End":"02:51.005","Text":"But I could write temperature or even temp perhaps would be a little bit better."},{"Start":"02:51.005 ","End":"02:52.910","Text":"Input temp for temperature."},{"Start":"02:52.910 ","End":"03:02.400","Text":"I\u0027ll give it an initial value 37.77778 and a semicolon."},{"Start":"03:02.400 ","End":"03:05.090","Text":"Then I\u0027ve been asked to declare in Part B"},{"Start":"03:05.090 ","End":"03:09.395","Text":"another variable to hold an output temperature again, of an appropriate type."},{"Start":"03:09.395 ","End":"03:11.180","Text":"Well, if the input was a float,"},{"Start":"03:11.180 ","End":"03:15.900","Text":"it would make sense for the output to be a float as well."},{"Start":"03:15.900 ","End":"03:19.415","Text":"I don\u0027t need to give it an initial value, haven\u0027t been asked to."},{"Start":"03:19.415 ","End":"03:22.280","Text":"I\u0027ll just end the line with a semicolon."},{"Start":"03:22.280 ","End":"03:23.510","Text":"We\u0027re on Part C now,"},{"Start":"03:23.510 ","End":"03:28.460","Text":"so we\u0027re asked to create a method inside the class called converts."},{"Start":"03:28.460 ","End":"03:31.085","Text":"Our method is where the code belongs."},{"Start":"03:31.085 ","End":"03:33.320","Text":"We saw when we did an initial exercise what"},{"Start":"03:33.320 ","End":"03:36.350","Text":"this looks like the structure of a Java program."},{"Start":"03:36.350 ","End":"03:39.065","Text":"Without going into too much detail,"},{"Start":"03:39.065 ","End":"03:43.625","Text":"you\u0027ll need to put in front of the name of the method a keyword void,"},{"Start":"03:43.625 ","End":"03:45.590","Text":"basically saying to the compiler,"},{"Start":"03:45.590 ","End":"03:48.350","Text":"don\u0027t expect anything to come back from this program."},{"Start":"03:48.350 ","End":"03:53.210","Text":"Then we put the name of the method and you put a pair of empty brackets for the moment."},{"Start":"03:53.210 ","End":"03:54.350","Text":"Later on in the course,"},{"Start":"03:54.350 ","End":"03:56.525","Text":"we\u0027ll find out what goes in those brackets."},{"Start":"03:56.525 ","End":"04:01.250","Text":"I\u0027ll close off my method with a closing brace here."},{"Start":"04:01.250 ","End":"04:06.380","Text":"It seems to be happy and you\u0027ll see in BlueJ highlights in yellow here,"},{"Start":"04:06.380 ","End":"04:11.275","Text":"to say that it\u0027s a method and the block is complete essentially."},{"Start":"04:11.275 ","End":"04:14.930","Text":"Code inside it should be indented it\u0027s good practice."},{"Start":"04:14.930 ","End":"04:17.120","Text":"It will still work if it doesn\u0027t but should"},{"Start":"04:17.120 ","End":"04:19.745","Text":"indent it just to make your code look a bit more readable."},{"Start":"04:19.745 ","End":"04:22.490","Text":"Now when I\u0027ve been asked to do in"},{"Start":"04:22.490 ","End":"04:27.020","Text":"Part D is to add a line that uses whatever operators are needed to"},{"Start":"04:27.020 ","End":"04:29.810","Text":"convert the imprint temperature from Celsius to"},{"Start":"04:29.810 ","End":"04:34.610","Text":"Fahrenheit and to assign the evaluated value to the output temperature value."},{"Start":"04:34.610 ","End":"04:41.300","Text":"Here I need to come up with a formula for this and we do a Google search for this."},{"Start":"04:41.300 ","End":"04:47.240","Text":"But what I\u0027m doing is I\u0027m trying to put a value into the output temp variable."},{"Start":"04:47.240 ","End":"04:50.675","Text":"That\u0027s where my expression will start output temp."},{"Start":"04:50.675 ","End":"04:52.805","Text":"Then the assignment operator,"},{"Start":"04:52.805 ","End":"04:55.700","Text":"because I want a value to go into output temp."},{"Start":"04:55.700 ","End":"04:59.960","Text":"Then the rest of the expression we\u0027ll do the calculation which calculates"},{"Start":"04:59.960 ","End":"05:07.130","Text":"a temperature in Fahrenheit when given a value in centigrade or degrees Celsius."},{"Start":"05:07.130 ","End":"05:09.050","Text":"If we have it,"},{"Start":"05:09.050 ","End":"05:12.515","Text":"the value that we want an input temp,"},{"Start":"05:12.515 ","End":"05:15.245","Text":"then that\u0027s how our expression is going to start off."},{"Start":"05:15.245 ","End":"05:19.355","Text":"If you were to look up what the conversion is,"},{"Start":"05:19.355 ","End":"05:21.710","Text":"do a web search for that."},{"Start":"05:21.710 ","End":"05:26.090","Text":"You\u0027ll find that the formula is the input temperature multiplied"},{"Start":"05:26.090 ","End":"05:31.775","Text":"by 9/5 and added to that should be 32,"},{"Start":"05:31.775 ","End":"05:33.935","Text":"and that should give you the results."},{"Start":"05:33.935 ","End":"05:37.550","Text":"Now, we won\u0027t get the correct result if we do"},{"Start":"05:37.550 ","End":"05:41.615","Text":"this and you might scratch your head and think of why wouldn\u0027t get the correct result."},{"Start":"05:41.615 ","End":"05:45.035","Text":"But actually, it comes down to this little bit here,"},{"Start":"05:45.035 ","End":"05:48.570","Text":"because this is a literal fraction"},{"Start":"05:48.570 ","End":"05:53.135","Text":"and by default what will happen is this will do an integer division."},{"Start":"05:53.135 ","End":"05:57.980","Text":"What you want to do is to force the compiler to consider this as a"},{"Start":"05:57.980 ","End":"06:03.110","Text":"fractional literal and it will work nicely."},{"Start":"06:03.110 ","End":"06:06.020","Text":"You could also work out what 9/5 is actually"},{"Start":"06:06.020 ","End":"06:10.895","Text":"1.8 and put 1.8 in there instead and that would do the job as well."},{"Start":"06:10.895 ","End":"06:12.110","Text":"If you don\u0027t do that,"},{"Start":"06:12.110 ","End":"06:16.385","Text":"you\u0027ll get an incorrect result and that will be the first little hurdle for you."},{"Start":"06:16.385 ","End":"06:21.890","Text":"Let\u0027s try and do the final part which says system out,"},{"Start":"06:21.890 ","End":"06:25.590","Text":"print line, and print the results basically."},{"Start":"06:25.590 ","End":"06:27.140","Text":"What is the result going to be?"},{"Start":"06:27.140 ","End":"06:29.975","Text":"Well, it\u0027s been stored into output temp."},{"Start":"06:29.975 ","End":"06:34.585","Text":"That is what we\u0027re looking to see."},{"Start":"06:34.585 ","End":"06:42.140","Text":"We\u0027ve done all the steps now from A to E. We probably written a few too many lines here."},{"Start":"06:42.140 ","End":"06:44.555","Text":"You should really, when you\u0027re writing a couple of lines,"},{"Start":"06:44.555 ","End":"06:47.555","Text":"test by compiling them as you\u0027re going along."},{"Start":"06:47.555 ","End":"06:49.130","Text":"If we click on compile here,"},{"Start":"06:49.130 ","End":"06:51.695","Text":"you\u0027ll see already it\u0027s found an error."},{"Start":"06:51.695 ","End":"06:55.930","Text":"Highlights in the margin here where the error is."},{"Start":"06:55.930 ","End":"06:57.350","Text":"If I click on the line,"},{"Start":"06:57.350 ","End":"07:02.539","Text":"it tells me incompatible types possible lossy conversion from double to float."},{"Start":"07:02.539 ","End":"07:04.160","Text":"What it\u0027s saying here is,"},{"Start":"07:04.160 ","End":"07:07.505","Text":"it\u0027s always assuming that if you put a fractional number,"},{"Start":"07:07.505 ","End":"07:10.820","Text":"that it\u0027s a double and it\u0027s trying to convert it from a"},{"Start":"07:10.820 ","End":"07:15.425","Text":"double to a float because it knows that that\u0027s what we want to put it into."},{"Start":"07:15.425 ","End":"07:18.020","Text":"We already saw this once before."},{"Start":"07:18.020 ","End":"07:22.820","Text":"We know that the trick here is just to put an f on the end to tell it that this"},{"Start":"07:22.820 ","End":"07:28.160","Text":"is a floating-point number and it should make the error go away."},{"Start":"07:28.160 ","End":"07:31.760","Text":"Let\u0027s compile and indeed the error does go away."},{"Start":"07:31.760 ","End":"07:35.675","Text":"We\u0027ve got a literal here which is assuming is a double."},{"Start":"07:35.675 ","End":"07:37.070","Text":"I\u0027m telling it no,"},{"Start":"07:37.070 ","End":"07:38.915","Text":"it\u0027s not double, it\u0027s a float."},{"Start":"07:38.915 ","End":"07:44.630","Text":"Therefore, I can assign it to a float without getting that warning error message."},{"Start":"07:44.630 ","End":"07:48.470","Text":"That now compiles with no syntax errors."},{"Start":"07:48.470 ","End":"07:52.715","Text":"What I\u0027m able to do now is I can close the editor."},{"Start":"07:52.715 ","End":"07:55.580","Text":"As it is asked me to do in"},{"Start":"07:55.580 ","End":"08:00.380","Text":"Part F while I\u0027ve actually compiled it and done Part F. Now I need to do Part G,"},{"Start":"08:00.380 ","End":"08:03.305","Text":"test it by creating an object from the class which you remember,"},{"Start":"08:03.305 ","End":"08:07.010","Text":"you right-click say new temperature converter app."},{"Start":"08:07.010 ","End":"08:10.340","Text":"It gives me a default name, I\u0027ll just accept."},{"Start":"08:10.340 ","End":"08:12.739","Text":"Then down here on the object workbench,"},{"Start":"08:12.739 ","End":"08:16.625","Text":"I\u0027ve got the object which I can run code on."},{"Start":"08:16.625 ","End":"08:22.940","Text":"I right-click now I select the name of the method that I wanted to run."},{"Start":"08:22.940 ","End":"08:25.130","Text":"I only have 1 method and it\u0027s called convert."},{"Start":"08:25.130 ","End":"08:31.305","Text":"I run it and it should print on the terminal the results and up pops my Terminal Window."},{"Start":"08:31.305 ","End":"08:34.385","Text":"The result is indeed what I was expecting,"},{"Start":"08:34.385 ","End":"08:36.410","Text":"which is a 100."},{"Start":"08:36.410 ","End":"08:39.290","Text":"Nice and simple program,"},{"Start":"08:39.290 ","End":"08:45.860","Text":"first useful program that we\u0027ve written really that converts a temperature from degrees"},{"Start":"08:45.860 ","End":"08:49.190","Text":"Celsius into Fahrenheit and displays the result on"},{"Start":"08:49.190 ","End":"08:53.540","Text":"the screen and only took a few lines of code to do that."},{"Start":"08:53.540 ","End":"08:56.675","Text":"But the key to it was this expression here,"},{"Start":"08:56.675 ","End":"09:04.415","Text":"which evaluated what this calculation is and then store the result into output temp,"},{"Start":"09:04.415 ","End":"09:07.400","Text":"which we then displayed on the screen."},{"Start":"09:07.400 ","End":"09:11.940","Text":"Thanks very much, and I\u0027ll see you in the next video."}],"ID":28022}],"Thumbnail":null,"ID":246358},{"Name":"Iterative Control Structures","TopicPlaylistFirstVideoID":0,"Duration":null,"Videos":[{"Watched":false,"Name":"For loop","Duration":"8m 41s","ChapterTopicVideoID":26440,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.570","Text":"Hello, welcome to the first of 2 videos where we look at"},{"Start":"00:03.570 ","End":"00:07.320","Text":"iterative structures available to programmers in high-level languages."},{"Start":"00:07.320 ","End":"00:08.700","Text":"By the end of this section,"},{"Start":"00:08.700 ","End":"00:13.065","Text":"you\u0027ll be able to contrast conditional control structures and iterative structures."},{"Start":"00:13.065 ","End":"00:16.395","Text":"Use a count terminated iterative structure."},{"Start":"00:16.395 ","End":"00:20.430","Text":"Use a condition terminated iterative structure and"},{"Start":"00:20.430 ","End":"00:25.140","Text":"select between top and bottom terminated iterative structures."},{"Start":"00:25.140 ","End":"00:26.970","Text":"In the previous topic, we saw"},{"Start":"00:26.970 ","End":"00:32.685","Text":"how conditional control structures allow us to execute or skip a block of instructions."},{"Start":"00:32.685 ","End":"00:36.735","Text":"Iteration is the repetitive execution"},{"Start":"00:36.735 ","End":"00:41.100","Text":"of a block of program statements until a termination condition is met."},{"Start":"00:41.100 ","End":"00:44.280","Text":"Rather than running or skipping a block code,"},{"Start":"00:44.280 ","End":"00:48.635","Text":"we\u0027re interested in repeatedly running all the instructions in the block."},{"Start":"00:48.635 ","End":"00:53.720","Text":"Instructions will continue to be carried out until some condition is no longer true."},{"Start":"00:53.720 ","End":"00:57.280","Text":"To understand iteration, let\u0027s look at a visual example."},{"Start":"00:57.280 ","End":"01:03.530","Text":"Let\u0027s say we\u0027re looking for a house on a street where the door numbers go from 1-100."},{"Start":"01:03.530 ","End":"01:09.140","Text":"We walk along the street starting from the door numbered 1 and inspect the number on each"},{"Start":"01:09.140 ","End":"01:15.050","Text":"in consecutive door until we reach the number we\u0027re looking for and then we stop."},{"Start":"01:15.050 ","End":"01:18.650","Text":"If we were looking for the house numbered 50, for example,"},{"Start":"01:18.650 ","End":"01:24.205","Text":"we\u0027d say we\u0027re iterating through the door numbers from 1-50."},{"Start":"01:24.205 ","End":"01:28.570","Text":"The operation we are performing is inspecting the door number."},{"Start":"01:28.570 ","End":"01:32.545","Text":"We do this repeatedly until we find the number we\u0027re interested in."},{"Start":"01:32.545 ","End":"01:34.390","Text":"Although in this example there was"},{"Start":"01:34.390 ","End":"01:37.735","Text":"only 1 single operation of inspecting the door number,"},{"Start":"01:37.735 ","End":"01:40.270","Text":"it could have involved several operations."},{"Start":"01:40.270 ","End":"01:45.100","Text":"For example, we may have been conducting a survey or doing some door-to-door selling."},{"Start":"01:45.100 ","End":"01:47.635","Text":"In that case, you might have knocked on the door,"},{"Start":"01:47.635 ","End":"01:52.255","Text":"awaited a response, and interacted with the person who opened the door."},{"Start":"01:52.255 ","End":"01:55.645","Text":"We then move on to the next door and repeat the same process."},{"Start":"01:55.645 ","End":"01:59.845","Text":"Carrying on until we visited every house in the street."},{"Start":"01:59.845 ","End":"02:03.640","Text":"Let\u0027s now compare conditional and iterative control structures"},{"Start":"02:03.640 ","End":"02:07.445","Text":"by looking at 2 fragments of different programs."},{"Start":"02:07.445 ","End":"02:09.000","Text":"On the first loop here,"},{"Start":"02:09.000 ","End":"02:11.645","Text":"the 2 flowchart fragments look quite similar."},{"Start":"02:11.645 ","End":"02:16.040","Text":"But there\u0027s an important difference you might grasp when thinking about it a little."},{"Start":"02:16.040 ","End":"02:19.805","Text":"Let\u0027s say the flowchart on the left represents a game."},{"Start":"02:19.805 ","End":"02:21.005","Text":"When the player is hit,"},{"Start":"02:21.005 ","End":"02:22.430","Text":"they lose a life."},{"Start":"02:22.430 ","End":"02:24.680","Text":"Whether the player is hit or not,"},{"Start":"02:24.680 ","End":"02:29.880","Text":"the movement is always in the direction down from A-C."},{"Start":"02:29.880 ","End":"02:32.950","Text":"It may go via point B,"},{"Start":"02:32.950 ","End":"02:35.090","Text":"if the player has been hit."},{"Start":"02:35.090 ","End":"02:38.885","Text":"But once the program flow has passed through the point A,"},{"Start":"02:38.885 ","End":"02:41.585","Text":"it doesn\u0027t return to point A."},{"Start":"02:41.585 ","End":"02:43.700","Text":"On the other flowchart."},{"Start":"02:43.700 ","End":"02:48.550","Text":"Points A and B are visited repeatedly."},{"Start":"02:48.550 ","End":"02:55.730","Text":"In fact, they keep on getting visited until door number 50 has been inspected and only"},{"Start":"02:55.730 ","End":"02:58.730","Text":"then does the program flow continue to"},{"Start":"02:58.730 ","End":"03:02.360","Text":"point C and onto the other instructions in the program."},{"Start":"03:02.360 ","End":"03:08.870","Text":"The program instructions run around and around in a loop here between A and B."},{"Start":"03:08.870 ","End":"03:11.390","Text":"In fact, this word loop is"},{"Start":"03:11.390 ","End":"03:17.255","Text":"the more informal term programmers use when referring to iterative control structures."},{"Start":"03:17.255 ","End":"03:19.340","Text":"A loop refers to a section of"},{"Start":"03:19.340 ","End":"03:23.225","Text":"a program that\u0027s being run repeatedly until it\u0027s terminated."},{"Start":"03:23.225 ","End":"03:26.240","Text":"With a conditional structure we saw earlier and we can see here"},{"Start":"03:26.240 ","End":"03:29.150","Text":"on the left, there\u0027s no repetition."},{"Start":"03:29.150 ","End":"03:32.460","Text":"Either 1 path is followed or the other."},{"Start":"03:32.460 ","End":"03:36.245","Text":"But previous instructions are not repeated."},{"Start":"03:36.245 ","End":"03:39.380","Text":"Most imperative high-level languages will have"},{"Start":"03:39.380 ","End":"03:42.785","Text":"a type of iterative control structure called a for loop."},{"Start":"03:42.785 ","End":"03:44.585","Text":"In its simplest form,"},{"Start":"03:44.585 ","End":"03:47.365","Text":"the for loop defines a block which is to be"},{"Start":"03:47.365 ","End":"03:52.625","Text":"repeated and repeatedly executes that block a certain number of times."},{"Start":"03:52.625 ","End":"03:56.780","Text":"How many times the loop runs and what range of values the variable takes"},{"Start":"03:56.780 ","End":"04:01.460","Text":"on is determined by the values given in the opening line."},{"Start":"04:01.460 ","End":"04:06.740","Text":"In addition, a variable takes on a value each time round the loop,"},{"Start":"04:06.740 ","End":"04:10.040","Text":"and that value is automatically updated without"},{"Start":"04:10.040 ","End":"04:13.525","Text":"any additional code being supplied by the programmer."},{"Start":"04:13.525 ","End":"04:18.960","Text":"Basic was a language used to teach beginners how to program in the 1960\u0027s onwards."},{"Start":"04:18.960 ","End":"04:23.410","Text":"For loops in basic are particularly easy to read for a beginner and so"},{"Start":"04:23.410 ","End":"04:28.225","Text":"we\u0027ll use an example in basic to understand the general operation of a for loop."},{"Start":"04:28.225 ","End":"04:31.405","Text":"After the initial keyword FOR,"},{"Start":"04:31.405 ","End":"04:34.960","Text":"we state the variable name being used in the loop."},{"Start":"04:34.960 ","End":"04:39.130","Text":"In this case, we\u0027ve called it num and it will start at the value"},{"Start":"04:39.130 ","End":"04:43.945","Text":"2 and will keep going until we get to 20,"},{"Start":"04:43.945 ","End":"04:47.215","Text":"but it will go up in steps of 2."},{"Start":"04:47.215 ","End":"04:53.350","Text":"Here we see the value of num when the program first enters the loop."},{"Start":"04:53.350 ","End":"04:55.650","Text":"Once the first line of code has been run,"},{"Start":"04:55.650 ","End":"04:59.405","Text":"the message output on the screen will be this."},{"Start":"04:59.405 ","End":"05:02.680","Text":"This line will generate this output."},{"Start":"05:02.680 ","End":"05:09.390","Text":"The next line then generates this output because the current value of num is 2."},{"Start":"05:09.390 ","End":"05:11.390","Text":"At the end of the code block,"},{"Start":"05:11.390 ","End":"05:16.220","Text":"num is automatically incremented by 2."},{"Start":"05:16.220 ","End":"05:22.805","Text":"As that was the step value we set in the opening line of the for loop statement."},{"Start":"05:22.805 ","End":"05:26.150","Text":"Then execution continues from the beginning of the loop"},{"Start":"05:26.150 ","End":"05:29.615","Text":"again and we see the new output on the screen."},{"Start":"05:29.615 ","End":"05:33.170","Text":"Once again, num is increased by 2,"},{"Start":"05:33.170 ","End":"05:38.510","Text":"and we go back to the beginning again and the block just keeps repeating and"},{"Start":"05:38.510 ","End":"05:45.280","Text":"outputs the new value of num increment by 2 again, and so on."},{"Start":"05:45.280 ","End":"05:51.345","Text":"Loop will now run 1 final time when num reaches 20."},{"Start":"05:51.345 ","End":"05:55.175","Text":"A final value of num is output to the screen"},{"Start":"05:55.175 ","End":"05:59.750","Text":"and it won\u0027t be increased anymore and execution will"},{"Start":"05:59.750 ","End":"06:04.790","Text":"continue past the next statement as the loops ended and"},{"Start":"06:04.790 ","End":"06:07.430","Text":"whatever instructions follow the loop will now be executed in"},{"Start":"06:07.430 ","End":"06:10.400","Text":"sequence or if there are no more instructions,"},{"Start":"06:10.400 ","End":"06:12.305","Text":"the program will end."},{"Start":"06:12.305 ","End":"06:16.070","Text":"The syntax for C-style languages including C++,"},{"Start":"06:16.070 ","End":"06:20.495","Text":"C Sharp and Java is a little more difficult to read,"},{"Start":"06:20.495 ","End":"06:23.390","Text":"but operates on exactly the same principles."},{"Start":"06:23.390 ","End":"06:27.120","Text":"We have to formally declare a variable for use in the for"},{"Start":"06:27.120 ","End":"06:31.010","Text":"loop and we can initialize it with initial value here."},{"Start":"06:31.010 ","End":"06:33.275","Text":"Then follows a semicolon,"},{"Start":"06:33.275 ","End":"06:35.780","Text":"and then the termination condition."},{"Start":"06:35.780 ","End":"06:37.970","Text":"In other words, when will the loop stop?"},{"Start":"06:37.970 ","End":"06:43.460","Text":"In this case, when num is no longer less than or equal to 20."},{"Start":"06:43.460 ","End":"06:46.170","Text":"Finally, after another semicolon,"},{"Start":"06:46.170 ","End":"06:50.015","Text":"we have the part where the variable is being incremented."},{"Start":"06:50.015 ","End":"06:54.080","Text":"The opening brace or curly bracket marks where"},{"Start":"06:54.080 ","End":"06:58.715","Text":"the block starts and there\u0027s no next command as there is with basic,"},{"Start":"06:58.715 ","End":"07:02.360","Text":"the closing curly bracket here does the job of"},{"Start":"07:02.360 ","End":"07:06.725","Text":"next in marking the end of the block of instructions that repeat."},{"Start":"07:06.725 ","End":"07:12.320","Text":"The syntax for Java is identical to C. The only difference being"},{"Start":"07:12.320 ","End":"07:19.414","Text":"the output line here being different for Java than C otherwise it\u0027s identical."},{"Start":"07:19.414 ","End":"07:21.020","Text":"Syntax for Python,"},{"Start":"07:21.020 ","End":"07:23.030","Text":"however, is a little different."},{"Start":"07:23.030 ","End":"07:28.520","Text":"We still give the name of the variable which takes on the successive values in the loop."},{"Start":"07:28.520 ","End":"07:34.270","Text":"But in Python, we create a set of numbers to iterate through using range."},{"Start":"07:34.270 ","End":"07:42.535","Text":"In this case, going from 2 to 22 in steps of 2. Why 22?"},{"Start":"07:42.535 ","End":"07:46.480","Text":"Well, Python differs from the other high-level languages in that it goes up to,"},{"Start":"07:46.480 ","End":"07:49.480","Text":"but not including the upper limit."},{"Start":"07:49.480 ","End":"07:56.905","Text":"If we had put 20 num would\u0027ve taken on values 2 up to 18, but not 20."},{"Start":"07:56.905 ","End":"08:00.535","Text":"Hence the 22, which also could have been 21."},{"Start":"08:00.535 ","End":"08:07.720","Text":"The start of the block here is marked with a colon and an indentation is used"},{"Start":"08:07.720 ","End":"08:15.020","Text":"to mark where the loop is and marks out the block and when there is no more indentation,"},{"Start":"08:15.020 ","End":"08:16.925","Text":"that would be the end of the block."},{"Start":"08:16.925 ","End":"08:21.020","Text":"So slightly different syntax for Python based on the fact that there are"},{"Start":"08:21.020 ","End":"08:25.730","Text":"no braces and the opening line is also quite different too."},{"Start":"08:25.730 ","End":"08:31.325","Text":"That\u0027s it for the first video where we looked at for loops which are count-controlled."},{"Start":"08:31.325 ","End":"08:34.925","Text":"In the next video, we\u0027ll look at condition-controlled loops,"},{"Start":"08:34.925 ","End":"08:39.080","Text":"which gives us a little bit more flexibility than a for loop."},{"Start":"08:39.080 ","End":"08:42.600","Text":"I\u0027ll see you then. Thank you."}],"ID":27347},{"Watched":false,"Name":"While loop","Duration":"5m ","ChapterTopicVideoID":26441,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:05.815","Text":"Hey everyone, welcome back to the second video on iterative control structures."},{"Start":"00:05.815 ","End":"00:09.940","Text":"Previously we learned that this type of structure allows us to repeatedly"},{"Start":"00:09.940 ","End":"00:14.770","Text":"execute a block of code until some sort of termination condition is met."},{"Start":"00:14.770 ","End":"00:18.759","Text":"The informal word we use to describe each iteration was loop."},{"Start":"00:18.759 ","End":"00:22.390","Text":"The first specific structure we encountered was the for loop."},{"Start":"00:22.390 ","End":"00:27.130","Text":"That\u0027s useful in situations when there are fixed number of iterations to be completed,"},{"Start":"00:27.130 ","End":"00:31.525","Text":"and when that number is known at the time that the loop starts, executing."},{"Start":"00:31.525 ","End":"00:35.500","Text":"Loop terminates as a result of the terminal value being reached."},{"Start":"00:35.500 ","End":"00:40.210","Text":"In this example, if we know that there are 50 doors we need to inspect,"},{"Start":"00:40.210 ","End":"00:42.930","Text":"the loop will terminate after 50."},{"Start":"00:42.930 ","End":"00:47.525","Text":"A more flexible type of loop involves a condition being satisfied."},{"Start":"00:47.525 ","End":"00:50.510","Text":"Rather than repeating a fixed number of times"},{"Start":"00:50.510 ","End":"00:53.930","Text":"the block will be repeated while some condition is true."},{"Start":"00:53.930 ","End":"00:57.080","Text":"Unsurprisingly, this is called a while loop."},{"Start":"00:57.080 ","End":"00:59.929","Text":"It involves our friend, the Boolean expression,"},{"Start":"00:59.929 ","End":"01:04.070","Text":"some condition or conditions that evaluate to a Boolean."},{"Start":"01:04.070 ","End":"01:09.710","Text":"On first look, it seems almost identical to an F structure with the keyword while,"},{"Start":"01:09.710 ","End":"01:11.480","Text":"replacing the keyword, if."},{"Start":"01:11.480 ","End":"01:17.030","Text":"But the difference is that if will either skip the block or run it once,"},{"Start":"01:17.030 ","End":"01:20.600","Text":"whereas while will repeatedly runs the statements in"},{"Start":"01:20.600 ","End":"01:25.085","Text":"the block until the Boolean expression evaluates to false."},{"Start":"01:25.085 ","End":"01:29.330","Text":"Let us look at an example in Java which would be very similar in"},{"Start":"01:29.330 ","End":"01:33.830","Text":"c. The Boolean expression being evaluated here is very simple."},{"Start":"01:33.830 ","End":"01:40.055","Text":"Is the number stored in the variable num less than 13."},{"Start":"01:40.055 ","End":"01:44.570","Text":"As we set the initial value of the num variable to 1,"},{"Start":"01:44.570 ","End":"01:48.530","Text":"we know that the expression will evaluate to 2, first-time round."},{"Start":"01:48.530 ","End":"01:51.925","Text":"Therefore the code inside this block will run."},{"Start":"01:51.925 ","End":"01:56.750","Text":"The first line of the 7 times table is therefore output here."},{"Start":"01:56.750 ","End":"01:58.670","Text":"Then on the next line,"},{"Start":"01:58.670 ","End":"02:00.305","Text":"we increment num,"},{"Start":"02:00.305 ","End":"02:02.705","Text":"so now contains 2."},{"Start":"02:02.705 ","End":"02:06.005","Text":"Execution will now continue from the top of the loop again,"},{"Start":"02:06.005 ","End":"02:08.705","Text":"just as we saw with a for loop previously."},{"Start":"02:08.705 ","End":"02:11.405","Text":"The Boolean evaluation happens again,"},{"Start":"02:11.405 ","End":"02:13.640","Text":"and num is still less than 13,"},{"Start":"02:13.640 ","End":"02:17.075","Text":"so the code inside the block will run again,"},{"Start":"02:17.075 ","End":"02:21.605","Text":"printing the second line of the 7 times table."},{"Start":"02:21.605 ","End":"02:24.395","Text":"Then num will be incremented again,"},{"Start":"02:24.395 ","End":"02:26.735","Text":"and now is 3."},{"Start":"02:26.735 ","End":"02:31.729","Text":"This continues on for as long as num is less than 13."},{"Start":"02:31.729 ","End":"02:35.460","Text":"Eventually, we will reach 12."},{"Start":"02:35.460 ","End":"02:37.820","Text":"Once num hits 13,"},{"Start":"02:37.820 ","End":"02:39.335","Text":"which it has done now,"},{"Start":"02:39.335 ","End":"02:47.300","Text":"the termination codons kicks in as num is now no longer less than 13, it\u0027s equal to 13."},{"Start":"02:47.300 ","End":"02:53.165","Text":"Execution will continue on from the line after the end of the while block."},{"Start":"02:53.165 ","End":"02:58.355","Text":"The syntax of Python admits only the curly brackets as usual,"},{"Start":"02:58.355 ","End":"03:01.115","Text":"and it starts with a colon."},{"Start":"03:01.115 ","End":"03:03.680","Text":"The block is repeated."},{"Start":"03:03.680 ","End":"03:07.475","Text":"The part that\u0027s indented is repeated as before."},{"Start":"03:07.475 ","End":"03:09.335","Text":"The principle is exactly the same."},{"Start":"03:09.335 ","End":"03:12.050","Text":"A Boolean condition is evaluated at the top."},{"Start":"03:12.050 ","End":"03:17.785","Text":"While it\u0027s true, the lines inside the block will keep on executing."},{"Start":"03:17.785 ","End":"03:20.780","Text":"Now, this 7 times table example doesn\u0027t seem"},{"Start":"03:20.780 ","End":"03:23.660","Text":"too different from the for loop example we looked at earlier."},{"Start":"03:23.660 ","End":"03:27.979","Text":"In fact, we could have achieved the same outcome using a for loop."},{"Start":"03:27.979 ","End":"03:30.415","Text":"Let\u0027s look at a different example."},{"Start":"03:30.415 ","End":"03:36.050","Text":"Here, we\u0027re using a flag variable to control when the loop terminates,"},{"Start":"03:36.050 ","End":"03:38.060","Text":"we came across a flag variable earlier."},{"Start":"03:38.060 ","End":"03:40.160","Text":"They used a signal that something has happened in"},{"Start":"03:40.160 ","End":"03:43.790","Text":"the program and can only contain the value true or false."},{"Start":"03:43.790 ","End":"03:48.410","Text":"This loop will continue executing the lines in green until"},{"Start":"03:48.410 ","End":"03:53.720","Text":"the flag variable found changes from false to true."},{"Start":"03:53.720 ","End":"03:59.930","Text":"We can see that this particular line here is where it changes from false,"},{"Start":"03:59.930 ","End":"04:04.480","Text":"which was set up with initially when the program started to true."},{"Start":"04:04.480 ","End":"04:10.100","Text":"We can see that found is only under very specific circumstances when"},{"Start":"04:10.100 ","End":"04:17.270","Text":"the variable multiple divided by the variable num2 gives a remainder of 0,"},{"Start":"04:17.270 ","End":"04:21.800","Text":"because the variable multiples being updated here inside the loop,"},{"Start":"04:21.800 ","End":"04:28.040","Text":"we have to calculate the remainder of multiple divided by num2 inside the loop as well."},{"Start":"04:28.040 ","End":"04:32.120","Text":"Then we use that to signal when the loop should end."},{"Start":"04:32.120 ","End":"04:37.025","Text":"The check to see whether the loop should run again is at the top in a while loop."},{"Start":"04:37.025 ","End":"04:39.140","Text":"Each time one iteration is completed,"},{"Start":"04:39.140 ","End":"04:43.840","Text":"we go back to the top again to see whether the code inside the block should run again."},{"Start":"04:43.840 ","End":"04:47.660","Text":"This type of loops therefore sometimes called a top terminated"},{"Start":"04:47.660 ","End":"04:51.980","Text":"loop because the termination check is happening at the top."},{"Start":"04:51.980 ","End":"04:54.560","Text":"We\u0027ll pause there and in the next video,"},{"Start":"04:54.560 ","End":"04:57.530","Text":"we\u0027ll have a look at variation on the while loop"},{"Start":"04:57.530 ","End":"05:01.500","Text":"called a do-while loop. I\u0027ll see you then."}],"ID":27348},{"Watched":false,"Name":"Do While loop","Duration":"6m 5s","ChapterTopicVideoID":26442,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.640","Text":"Hello again everyone. Welcome back to"},{"Start":"00:02.640 ","End":"00:06.180","Text":"this third video in a sequence of videos on iteration."},{"Start":"00:06.180 ","End":"00:07.560","Text":"In the previous video,"},{"Start":"00:07.560 ","End":"00:10.950","Text":"we looked at the while loop and iteration structure that involves"},{"Start":"00:10.950 ","End":"00:15.405","Text":"a conditional evaluation at the top of a block of code to be repeated,"},{"Start":"00:15.405 ","End":"00:19.245","Text":"and this type of loop is therefore called a top terminated loop."},{"Start":"00:19.245 ","End":"00:23.595","Text":"Looking at the earlier example of the 7 times table program,"},{"Start":"00:23.595 ","End":"00:25.365","Text":"it\u0027s easy to see why."},{"Start":"00:25.365 ","End":"00:31.185","Text":"The decision to continue or terminate the loop is made at the top here."},{"Start":"00:31.185 ","End":"00:36.080","Text":"As soon as num is no longer less than 13,"},{"Start":"00:36.080 ","End":"00:38.309","Text":"the loop will terminate."},{"Start":"00:38.309 ","End":"00:41.540","Text":"While num is less than 13,"},{"Start":"00:41.540 ","End":"00:48.245","Text":"execution will continue from point A to point B and back again."},{"Start":"00:48.245 ","End":"00:53.705","Text":"An alternative is where the termination check happens at the bottom of the loop."},{"Start":"00:53.705 ","End":"00:57.290","Text":"This example shows a typical keyboard-driven program"},{"Start":"00:57.290 ","End":"01:00.320","Text":"where a user enters a single letter as an option,"},{"Start":"01:00.320 ","End":"01:01.970","Text":"A, B, C,"},{"Start":"01:01.970 ","End":"01:05.225","Text":"or whatever, and that triggers some action."},{"Start":"01:05.225 ","End":"01:08.815","Text":"Option q would quit the program."},{"Start":"01:08.815 ","End":"01:12.470","Text":"We see that on entry to the loop at point A,"},{"Start":"01:12.470 ","End":"01:17.225","Text":"the variable k stores whatever key was typed at the keyboard."},{"Start":"01:17.225 ","End":"01:21.350","Text":"Then code within the symbol labeled menu is"},{"Start":"01:21.350 ","End":"01:25.385","Text":"executed and some action is performed depending on what key was pressed,"},{"Start":"01:25.385 ","End":"01:28.370","Text":"and then the check at the bottom here determines"},{"Start":"01:28.370 ","End":"01:31.490","Text":"whether the loop will continue back to point A or not."},{"Start":"01:31.490 ","End":"01:34.745","Text":"In this example, it will keep looping back,"},{"Start":"01:34.745 ","End":"01:40.385","Text":"while k is not equal to the lowercase letter q."},{"Start":"01:40.385 ","End":"01:47.400","Text":"While it\u0027s not, it will loop back to A as soon as it does contain q,"},{"Start":"01:47.400 ","End":"01:51.740","Text":"it will exit at point C. In C and Java,"},{"Start":"01:51.740 ","End":"01:57.515","Text":"this bottom terminated loop is called a do while loop or sometimes just a do loop."},{"Start":"01:57.515 ","End":"02:01.955","Text":"You can see here the program we wrote earlier for the 7 times table,"},{"Start":"02:01.955 ","End":"02:06.935","Text":"using while is almost identical when using do while,"},{"Start":"02:06.935 ","End":"02:11.870","Text":"which is the opening and closing lines changing."},{"Start":"02:11.870 ","End":"02:15.500","Text":"Note that there needs to be a semicolon here,"},{"Start":"02:15.500 ","End":"02:19.265","Text":"after the while, or you\u0027ll get an error when compiling."},{"Start":"02:19.265 ","End":"02:24.770","Text":"You recall we said earlier that lines in C or Java always end in a semicolon or"},{"Start":"02:24.770 ","End":"02:28.220","Text":"curly bracket as this block is being"},{"Start":"02:28.220 ","End":"02:32.810","Text":"repeatedly executed and it\u0027s before the while statement."},{"Start":"02:32.810 ","End":"02:36.485","Text":"There are no curly brackets after the Boolean condition,"},{"Start":"02:36.485 ","End":"02:40.670","Text":"so we need this semicolon to end the line."},{"Start":"02:40.670 ","End":"02:43.280","Text":"Looking at the example from the flowchart earlier,"},{"Start":"02:43.280 ","End":"02:45.125","Text":"here\u0027s the code in C,"},{"Start":"02:45.125 ","End":"02:51.004","Text":"which will take an input character from the keyboard and then simply"},{"Start":"02:51.004 ","End":"02:54.215","Text":"output the same character to the screen rather than doing anything"},{"Start":"02:54.215 ","End":"02:57.890","Text":"useful like running a particular manual operation."},{"Start":"02:57.890 ","End":"03:00.320","Text":"We\u0027ve done that just to keep the code simple."},{"Start":"03:00.320 ","End":"03:06.360","Text":"It will keep doing this for any key except for lowercase q."},{"Start":"03:06.360 ","End":"03:08.705","Text":"If lowercase q is entered,"},{"Start":"03:08.705 ","End":"03:10.565","Text":"the loop terminates,"},{"Start":"03:10.565 ","End":"03:12.870","Text":"and the program ends."},{"Start":"03:12.870 ","End":"03:18.080","Text":"do while is useful in cases where the loop will always run at least once."},{"Start":"03:18.080 ","End":"03:22.550","Text":"Here we want to read the key from the keyboard to know what to do."},{"Start":"03:22.550 ","End":"03:27.380","Text":"The code to read the input key may as well be inside the loop."},{"Start":"03:27.380 ","End":"03:31.100","Text":"Every time around the loop we want to get a different input to allow the user of"},{"Start":"03:31.100 ","End":"03:35.960","Text":"the program to enter another option of the available options A,"},{"Start":"03:35.960 ","End":"03:37.490","Text":"B, C, D, or whatever."},{"Start":"03:37.490 ","End":"03:40.655","Text":"Contrast this with the top terminated loop,"},{"Start":"03:40.655 ","End":"03:44.000","Text":"which checks the condition before going into"},{"Start":"03:44.000 ","End":"03:48.680","Text":"the loop and could potentially not execute the code inside the loop at all."},{"Start":"03:48.680 ","End":"03:52.730","Text":"We need to have an extra line to read the key before we even"},{"Start":"03:52.730 ","End":"03:57.425","Text":"get to the loop so that we can compare it to lowercase q."},{"Start":"03:57.425 ","End":"04:00.020","Text":"We\u0027ve also had to reorganize the lines"},{"Start":"04:00.020 ","End":"04:03.979","Text":"inside the loop so the character is displayed first,"},{"Start":"04:03.979 ","End":"04:09.020","Text":"and the key is read again on the second line inside the block."},{"Start":"04:09.020 ","End":"04:13.085","Text":"As you can see here, they are in a different order in the do while loop."},{"Start":"04:13.085 ","End":"04:15.425","Text":"Python doesn\u0027t have a do while loop,"},{"Start":"04:15.425 ","End":"04:20.240","Text":"and you can achieve a similar effect using if and break statements,"},{"Start":"04:20.240 ","End":"04:23.450","Text":"but this is not considered a good programming practice."},{"Start":"04:23.450 ","End":"04:26.450","Text":"You can do pretty much anything you need to with a while loop,"},{"Start":"04:26.450 ","End":"04:30.125","Text":"but there may be a few more lines needed as we\u0027ve seen here,"},{"Start":"04:30.125 ","End":"04:37.490","Text":"and depending on the situation it might not read as elegantly as a do while loop."},{"Start":"04:37.490 ","End":"04:41.535","Text":"Finally, it\u0027s possible to create a loop that never ends."},{"Start":"04:41.535 ","End":"04:44.285","Text":"We call this an infinite loop."},{"Start":"04:44.285 ","End":"04:51.470","Text":"In this example, the Boolean expression being evaluated is simply the keyword true,"},{"Start":"04:51.470 ","End":"04:53.540","Text":"which will always evaluate to true."},{"Start":"04:53.540 ","End":"04:56.660","Text":"Therefore, a termination condition is never going to be"},{"Start":"04:56.660 ","End":"04:59.990","Text":"met and this loop will continue forever."},{"Start":"04:59.990 ","End":"05:02.510","Text":"You might ask, why would you ever want to do this?"},{"Start":"05:02.510 ","End":"05:04.712","Text":"But it is actually surprisingly common."},{"Start":"05:04.712 ","End":"05:09.170","Text":"A software that\u0027s written for hardware that doesn\u0027t ever stop, for example,"},{"Start":"05:09.170 ","End":"05:13.879","Text":"monitoring systems such as an alarm system or a temperature control,"},{"Start":"05:13.879 ","End":"05:16.070","Text":"they won\u0027t ever need to quit."},{"Start":"05:16.070 ","End":"05:17.510","Text":"If you want it to stop,"},{"Start":"05:17.510 ","End":"05:22.115","Text":"you simply power down the hardware that your software is running on."},{"Start":"05:22.115 ","End":"05:24.770","Text":"However, it\u0027s also possible to accidentally create"},{"Start":"05:24.770 ","End":"05:27.829","Text":"an infinite loop biological error in a program."},{"Start":"05:27.829 ","End":"05:32.195","Text":"It\u0027s a programmer\u0027s responsibility to look at and test their code"},{"Start":"05:32.195 ","End":"05:35.390","Text":"carefully to make sure that it\u0027s possible for the"},{"Start":"05:35.390 ","End":"05:38.990","Text":"termination condition in any loops to be met."},{"Start":"05:38.990 ","End":"05:40.865","Text":"That\u0027s it for this topic."},{"Start":"05:40.865 ","End":"05:43.940","Text":"In this section, we learned how to contrast"},{"Start":"05:43.940 ","End":"05:47.405","Text":"conditional control structures and iterative structures,"},{"Start":"05:47.405 ","End":"05:50.420","Text":"how to use a count terminated iterative structure,"},{"Start":"05:50.420 ","End":"05:54.420","Text":"how to use a condition terminated iterative structure,"},{"Start":"05:54.420 ","End":"06:00.620","Text":"and to select between top and bottom terminated iterative structures."},{"Start":"06:00.620 ","End":"06:05.430","Text":"Thank you very much, and I\u0027ll see you for the next one."}],"ID":27349},{"Watched":false,"Name":"Exercise 1","Duration":"5m 28s","ChapterTopicVideoID":26936,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.665","Text":"Hi. In this first exercise we\u0027ve been asked to create a new project in BlueJ,"},{"Start":"00:04.665 ","End":"00:07.560","Text":"and a new class inside it called IterationApp."},{"Start":"00:07.560 ","End":"00:12.460","Text":"In part a, we are then asked to create a new method called forCountUp()."},{"Start":"00:12.460 ","End":"00:17.250","Text":"In part b, to use a for-loop to output the numbers from 1-10."},{"Start":"00:17.250 ","End":"00:21.705","Text":"In part c, we\u0027re asked to create another method called forCountDown(),"},{"Start":"00:21.705 ","End":"00:25.320","Text":"and then in part d to use a for-loop this time to"},{"Start":"00:25.320 ","End":"00:28.875","Text":"output the numbers from 5-1, ending on 1."},{"Start":"00:28.875 ","End":"00:30.750","Text":"Finally, in part e,"},{"Start":"00:30.750 ","End":"00:33.420","Text":"we\u0027re asked to test both methods by creating"},{"Start":"00:33.420 ","End":"00:37.635","Text":"an object on the workbench and to correct any errors found."},{"Start":"00:37.635 ","End":"00:41.330","Text":"The first thing we need to do is to create the project,"},{"Start":"00:41.330 ","End":"00:45.380","Text":"so I\u0027ll go ahead and call mine Topic6."},{"Start":"00:45.380 ","End":"00:47.944","Text":"Then within the project,"},{"Start":"00:47.944 ","End":"00:56.128","Text":"we need to create a new class and we\u0027ve been asked to call that class IterationApp,"},{"Start":"00:56.128 ","End":"01:02.400","Text":"and then within there for part a I need to create a method called countUp."},{"Start":"01:02.800 ","End":"01:09.310","Text":"I\u0027ll remove the initial code from the class that BlueJ has created for me,"},{"Start":"01:09.310 ","End":"01:13.135","Text":"and I\u0027ll create my method called countUp()."},{"Start":"01:13.135 ","End":"01:15.244","Text":"That\u0027s the beginning,"},{"Start":"01:15.244 ","End":"01:17.570","Text":"and what I now need to do is to create"},{"Start":"01:17.570 ","End":"01:23.235","Text":"my for-loop to output the numbers from 1-10 in part b."},{"Start":"01:23.235 ","End":"01:25.323","Text":"For is the keyword."},{"Start":"01:25.323 ","End":"01:27.285","Text":"I need to round brackets,"},{"Start":"01:27.285 ","End":"01:30.035","Text":"and then I start with the initial value."},{"Start":"01:30.035 ","End":"01:32.060","Text":"Because I don\u0027t have a variable yet,"},{"Start":"01:32.060 ","End":"01:36.050","Text":"I can declare a variable inside the for-loop so for int"},{"Start":"01:36.050 ","End":"01:41.180","Text":"i and start with the initial value of 1 and then a semicolon."},{"Start":"01:41.180 ","End":"01:43.250","Text":"The next part is the termination clause."},{"Start":"01:43.250 ","End":"01:45.170","Text":"When does the loop stop?"},{"Start":"01:45.170 ","End":"01:49.445","Text":"In my case it\u0027s when I get to beyond 10."},{"Start":"01:49.445 ","End":"01:55.150","Text":"I\u0027m going to say int i equals 1;"},{"Start":"01:55.150 ","End":"01:58.345","Text":"i is less than or equal to 10."},{"Start":"01:58.345 ","End":"02:03.410","Text":"I could make that less than 11 if I prefer and have the same effect,"},{"Start":"02:03.410 ","End":"02:07.265","Text":"but I think this will do me and it\u0027s reasonably readable."},{"Start":"02:07.265 ","End":"02:10.430","Text":"It\u0027s clear that I\u0027m going between 1 and 10."},{"Start":"02:10.430 ","End":"02:14.045","Text":"Then the last part is what do I increment i by?"},{"Start":"02:14.045 ","End":"02:16.460","Text":"I want to increment by one each time around the loop,"},{"Start":"02:16.460 ","End":"02:19.340","Text":"so the best thing for me to do is to just use the increment operator"},{"Start":"02:19.340 ","End":"02:22.630","Text":"there and that will increment by 1."},{"Start":"02:22.630 ","End":"02:26.630","Text":"Now, whatever I put between the curly brackets here will"},{"Start":"02:26.630 ","End":"02:30.479","Text":"be the part that\u0027s going to be repeatedly run,"},{"Start":"02:30.479 ","End":"02:34.580","Text":"and I just want a single line inside my loop that outputs"},{"Start":"02:34.580 ","End":"02:39.500","Text":"the current value of the i variable."},{"Start":"02:39.500 ","End":"02:47.810","Text":"This should put out the numbers 1-10 each on a separate line if that works successfully."},{"Start":"02:47.810 ","End":"02:50.015","Text":"That\u0027s countUp() down,"},{"Start":"02:50.015 ","End":"02:53.180","Text":"and I\u0027ll just check that it compiles without any errors before I move"},{"Start":"02:53.180 ","End":"02:56.480","Text":"on because I\u0027m not going to test it yet and that seems to be fine."},{"Start":"02:56.480 ","End":"03:01.744","Text":"I can now do the second part of part c of this exercise,"},{"Start":"03:01.744 ","End":"03:04.129","Text":"so it\u0027s called forCountDown(),"},{"Start":"03:04.129 ","End":"03:06.570","Text":"another method I\u0027ve been asked to create."},{"Start":"03:06.570 ","End":"03:10.160","Text":"I could\u0027ve done it in the previous one, but that\u0027s fine."},{"Start":"03:10.160 ","End":"03:14.780","Text":"I can do in separate methods just for ease of testing I guess."},{"Start":"03:14.780 ","End":"03:18.710","Text":"Now this one we have to go from 5-1,"},{"Start":"03:18.710 ","End":"03:20.765","Text":"so I need 2."},{"Start":"03:20.765 ","End":"03:23.180","Text":"Interestingly, I could have a variable"},{"Start":"03:23.180 ","End":"03:27.305","Text":"declared up here which both methods would have available."},{"Start":"03:27.305 ","End":"03:29.060","Text":"If I\u0027m going to declare a variable in"},{"Start":"03:29.060 ","End":"03:31.565","Text":"one method it\u0027s not accessible in the other method,"},{"Start":"03:31.565 ","End":"03:33.335","Text":"so I have to declare it again."},{"Start":"03:33.335 ","End":"03:37.125","Text":"I\u0027m going to do that here. I\u0027ll call it i again and they\u0027ll be completely separate."},{"Start":"03:37.125 ","End":"03:39.995","Text":"They are independent of each other because they\u0027re in different methods,"},{"Start":"03:39.995 ","End":"03:44.450","Text":"and I\u0027m going to start this time at 5."},{"Start":"03:44.450 ","End":"03:50.450","Text":"The termination clause is to say is it greater than or equal to 0?"},{"Start":"03:50.450 ","End":"03:52.730","Text":"I could say greater than minus 1,"},{"Start":"03:52.730 ","End":"03:56.720","Text":"but I\u0027m sure you\u0027ll agree that\u0027s a bit more readable to say greater than or equal to 0."},{"Start":"03:56.720 ","End":"03:59.330","Text":"This time instead of incrementing i,"},{"Start":"03:59.330 ","End":"04:01.850","Text":"I\u0027m going to decrement it."},{"Start":"04:01.850 ","End":"04:06.620","Text":"Meaning, I\u0027m going to take 1 off the value of i each time around the loop."},{"Start":"04:06.620 ","End":"04:10.280","Text":"The rest is the same as what we had previously,"},{"Start":"04:10.280 ","End":"04:13.745","Text":"so I might as well just copy that line rather than type it out."},{"Start":"04:13.745 ","End":"04:20.040","Text":"In this one, it should print out the numbers from 5-0."},{"Start":"04:20.040 ","End":"04:22.690","Text":"In fact actually I have been asked to end on 1,"},{"Start":"04:22.690 ","End":"04:24.850","Text":"so it doesn\u0027t need to be greater than 0."},{"Start":"04:24.850 ","End":"04:27.490","Text":"It needs to be greater than or equal to 1."},{"Start":"04:27.490 ","End":"04:31.195","Text":"If I had done greater than 0 that would have worked as well,"},{"Start":"04:31.195 ","End":"04:34.240","Text":"but not greater than or equal to 0 because that would have"},{"Start":"04:34.240 ","End":"04:38.515","Text":"printed the number 0 and I wasn\u0027t asked to do that in the exercise."},{"Start":"04:38.515 ","End":"04:40.120","Text":"Let\u0027s compile that."},{"Start":"04:40.120 ","End":"04:41.570","Text":"There are no errors,"},{"Start":"04:41.570 ","End":"04:45.100","Text":"and let\u0027s see if it generates the output that I\u0027m expecting."},{"Start":"04:45.100 ","End":"04:50.470","Text":"I\u0027ll run first of all countUp() and I expect the numbers to go from 1-10, and they do."},{"Start":"04:50.470 ","End":"04:51.910","Text":"There we go, 1-10."},{"Start":"04:51.910 ","End":"04:54.925","Text":"Let\u0027s try countDown() and see what that does."},{"Start":"04:54.925 ","End":"04:58.235","Text":"CountDown, then I\u0027m going to just test,"},{"Start":"04:58.235 ","End":"05:04.610","Text":"and that does generate the numbers from 5-1 as I would expect."},{"Start":"05:04.610 ","End":"05:09.109","Text":"If you have had different output from your test methods,"},{"Start":"05:09.109 ","End":"05:15.319","Text":"you probably want to check this little clause here and here for the correct values."},{"Start":"05:15.319 ","End":"05:18.505","Text":"For example you might have put 0 there as I initially did,"},{"Start":"05:18.505 ","End":"05:19.780","Text":"and you would count from"},{"Start":"05:19.780 ","End":"05:25.065","Text":"5-0 rather than 5-1 which is what we were asked to do in the question."},{"Start":"05:25.065 ","End":"05:26.955","Text":"That\u0027s it for this exercise,"},{"Start":"05:26.955 ","End":"05:29.140","Text":"I\u0027ll see you for the next one."}],"ID":28024},{"Watched":false,"Name":"Exercise 2","Duration":"3m 39s","ChapterTopicVideoID":26937,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:04.410","Text":"Hello, again. In this exercise we\u0027ve been asked in the same class as previously to"},{"Start":"00:04.410 ","End":"00:09.225","Text":"create a new method in part a called forCountIn2s."},{"Start":"00:09.225 ","End":"00:16.290","Text":"Then in part b, to use a for-loop to output the numbers from 2-24 in steps of 2."},{"Start":"00:16.290 ","End":"00:21.320","Text":"In part c, we\u0027re asked to create a new method called forCountIn10s."},{"Start":"00:21.320 ","End":"00:23.810","Text":"Then in part d, inside that method,"},{"Start":"00:23.810 ","End":"00:30.500","Text":"we\u0027re asked to use a for-loop to output numbers from 100 to 0 in steps of minus 10."},{"Start":"00:30.500 ","End":"00:32.180","Text":"Finally, in part e,"},{"Start":"00:32.180 ","End":"00:35.060","Text":"we\u0027re asked to test both methods by creating"},{"Start":"00:35.060 ","End":"00:39.005","Text":"an object on the workbench and to correct any errors found."},{"Start":"00:39.005 ","End":"00:42.110","Text":"Now, we\u0027ve been asked to add a new method"},{"Start":"00:42.110 ","End":"00:45.050","Text":"in the same class as previously Iteration app,"},{"Start":"00:45.050 ","End":"00:48.575","Text":"and call this method CountIn2s."},{"Start":"00:48.575 ","End":"00:50.345","Text":"Let\u0027s go ahead and do that."},{"Start":"00:50.345 ","End":"00:52.370","Text":"After the previous method,"},{"Start":"00:52.370 ","End":"00:54.110","Text":"I can create a new one."},{"Start":"00:54.110 ","End":"00:57.245","Text":"I\u0027m going to call it forCountIn2s."},{"Start":"00:57.245 ","End":"01:01.265","Text":"Of course, I could have created it before the previous method if I wanted to."},{"Start":"01:01.265 ","End":"01:03.560","Text":"Wouldn\u0027t make any difference."},{"Start":"01:03.560 ","End":"01:06.695","Text":"There we go for the opening line."},{"Start":"01:06.695 ","End":"01:13.595","Text":"What we need to do is use steps of 2 to output the numbers from 2-24."},{"Start":"01:13.595 ","End":"01:17.510","Text":"What I\u0027m going to do is I\u0027m just going to copy what I had up here,"},{"Start":"01:17.510 ","End":"01:19.430","Text":"save myself some typing,"},{"Start":"01:19.430 ","End":"01:20.990","Text":"and put it down here."},{"Start":"01:20.990 ","End":"01:24.200","Text":"Because this variable is in a different method,"},{"Start":"01:24.200 ","End":"01:25.610","Text":"I do need to declare it, again,"},{"Start":"01:25.610 ","End":"01:27.410","Text":"even though it\u0027s in the same class,"},{"Start":"01:27.410 ","End":"01:30.736","Text":"I have to declare my variables inside the methods,"},{"Start":"01:30.736 ","End":"01:32.059","Text":"unless I put them up here,"},{"Start":"01:32.059 ","End":"01:36.245","Text":"and then the variables will be available to all the methods in the class."},{"Start":"01:36.245 ","End":"01:38.510","Text":"But I\u0027ll just do it again in here."},{"Start":"01:38.510 ","End":"01:42.710","Text":"What I\u0027ve got to do now is start at 2,"},{"Start":"01:42.710 ","End":"01:45.650","Text":"and I want to go up to 24."},{"Start":"01:45.650 ","End":"01:47.780","Text":"But because I want to go in steps of 2,"},{"Start":"01:47.780 ","End":"01:49.580","Text":"I can\u0027t use the increment operator."},{"Start":"01:49.580 ","End":"01:52.505","Text":"I have to say i equals i plus 2."},{"Start":"01:52.505 ","End":"01:53.900","Text":"It\u0027s as simple as that."},{"Start":"01:53.900 ","End":"01:56.360","Text":"That will do what I\u0027ve been asked to do,"},{"Start":"01:56.360 ","End":"01:57.890","Text":"which is to go from 2-24."},{"Start":"01:57.890 ","End":"02:00.245","Text":"We\u0027ll see that in a moment when we test it."},{"Start":"02:00.245 ","End":"02:01.850","Text":"In part c,"},{"Start":"02:01.850 ","End":"02:07.595","Text":"I need to create another method called CountIn10s."},{"Start":"02:07.595 ","End":"02:11.383","Text":"What I\u0027ll do for that is I\u0027ll copy this,"},{"Start":"02:11.383 ","End":"02:14.600","Text":"and paste it below and just change the name."},{"Start":"02:14.600 ","End":"02:16.550","Text":"You\u0027ll see it\u0027s giving me an error message here because I\u0027ve"},{"Start":"02:16.550 ","End":"02:18.965","Text":"already got a method called CountIn2s."},{"Start":"02:18.965 ","End":"02:21.450","Text":"Let\u0027s change it to CountIn10s."},{"Start":"02:22.390 ","End":"02:27.440","Text":"We, obviously, want to go from 100,"},{"Start":"02:27.440 ","End":"02:31.145","Text":"as that\u0027s what the question asked for, to 0."},{"Start":"02:31.145 ","End":"02:33.050","Text":"This has got to be different."},{"Start":"02:33.050 ","End":"02:34.546","Text":"So I\u0027m going to say,"},{"Start":"02:34.546 ","End":"02:36.680","Text":"greater than or equal to 0,"},{"Start":"02:36.680 ","End":"02:39.230","Text":"or I could say greater than minus 1 if I wanted to,"},{"Start":"02:39.230 ","End":"02:41.895","Text":"but I would say this reads probably a little bit better."},{"Start":"02:41.895 ","End":"02:48.270","Text":"What we\u0027re doing to i is we\u0027re changing it by 10 each time around the loop."},{"Start":"02:48.270 ","End":"02:50.590","Text":"So we\u0027ve got to say i equals i minus 10."},{"Start":"02:52.190 ","End":"02:56.340","Text":"Let\u0027s have a go at running that."},{"Start":"02:56.340 ","End":"02:58.515","Text":"Now is when I compile it."},{"Start":"02:58.515 ","End":"03:04.920","Text":"Let\u0027s see if I get the output that I\u0027m expecting for CountIn2s,"},{"Start":"03:04.920 ","End":"03:07.730","Text":"I get 2 up to 24,"},{"Start":"03:07.730 ","End":"03:09.680","Text":"which is exactly what I expect."},{"Start":"03:09.680 ","End":"03:11.975","Text":"Then for CountIn10s,"},{"Start":"03:11.975 ","End":"03:16.070","Text":"I get 100 down to 0,"},{"Start":"03:16.070 ","End":"03:17.514","Text":"which is, again,"},{"Start":"03:17.514 ","End":"03:18.950","Text":"exactly what I expect."},{"Start":"03:18.950 ","End":"03:21.575","Text":"Once again, if you\u0027ve got an error,"},{"Start":"03:21.575 ","End":"03:26.785","Text":"check whether you\u0027ve got the right conditionals in the middle of these 2 statements,"},{"Start":"03:26.785 ","End":"03:29.690","Text":"and you\u0027ll probably find that that does what you want."},{"Start":"03:29.690 ","End":"03:35.232","Text":"That\u0027s it for simple for-loops in first 2 exercises."},{"Start":"03:35.232 ","End":"03:36.620","Text":"So we\u0027ll move on to something a little bit more"},{"Start":"03:36.620 ","End":"03:39.870","Text":"useful in the next exercise, and I\u0027ll see you then."}],"ID":28025},{"Watched":false,"Name":"Exercise 3","Duration":"6m 7s","ChapterTopicVideoID":26938,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.460","Text":"Hi everyone. In this exercise,"},{"Start":"00:02.460 ","End":"00:05.640","Text":"we\u0027ve been asked to create a new method called sevenTimesTable,"},{"Start":"00:05.640 ","End":"00:08.640","Text":"and then within there to create an integer variable called"},{"Start":"00:08.640 ","End":"00:11.730","Text":"table and to initialize it with the value 7."},{"Start":"00:11.730 ","End":"00:16.035","Text":"Then a second integer variable called multiplier with no initial value."},{"Start":"00:16.035 ","End":"00:19.260","Text":"In part b, we\u0027re asked to use a for loop to iterate"},{"Start":"00:19.260 ","End":"00:23.190","Text":"the multiplier variable through the numbers 1-12."},{"Start":"00:23.190 ","End":"00:26.370","Text":"In part c, we\u0027re asked inside the for loop"},{"Start":"00:26.370 ","End":"00:29.610","Text":"to output the contents of the multiplier variable,"},{"Start":"00:29.610 ","End":"00:32.235","Text":"followed by the string x,"},{"Start":"00:32.235 ","End":"00:35.880","Text":"followed by the contents of the table variable,"},{"Start":"00:35.880 ","End":"00:38.505","Text":"followed by the string equals."},{"Start":"00:38.505 ","End":"00:41.750","Text":"In part d, we\u0027re asked on the same line as the previous output to"},{"Start":"00:41.750 ","End":"00:45.760","Text":"output the product of the multiplier and table variables."},{"Start":"00:45.760 ","End":"00:47.440","Text":"Then finally in part e,"},{"Start":"00:47.440 ","End":"00:50.923","Text":"we are asked to test the method by creating an object on the workbench,"},{"Start":"00:50.923 ","End":"00:56.015","Text":"checking that all 12 lines of the sevenTimesTable are correctly output,"},{"Start":"00:56.015 ","End":"00:59.170","Text":"and to correct any errors if found."},{"Start":"00:59.170 ","End":"01:07.055","Text":"Let\u0027s then create a new method called sevenTimesTables inside existing class."},{"Start":"01:07.055 ","End":"01:10.355","Text":"Let\u0027s do that."},{"Start":"01:10.355 ","End":"01:15.080","Text":"The first part is asking us to create an integer variable called table and to"},{"Start":"01:15.080 ","End":"01:21.495","Text":"initialize it with the value 7, and that\u0027s done."},{"Start":"01:21.495 ","End":"01:24.385","Text":"Then a second multiplier,"},{"Start":"01:24.385 ","End":"01:27.910","Text":"a variable called multiplier with no initial values."},{"Start":"01:27.910 ","End":"01:35.590","Text":"I\u0027m going to assume that\u0027s a integer as well and no initial value given. That\u0027s fine."},{"Start":"01:35.590 ","End":"01:39.295","Text":"Now, I\u0027m now being asked to use a for loop to"},{"Start":"01:39.295 ","End":"01:44.200","Text":"iterate the multiplier variable through the numbers 1-12,"},{"Start":"01:44.200 ","End":"01:49.208","Text":"which is a way of saying I wanted to take on the values 1,"},{"Start":"01:49.208 ","End":"01:50.398","Text":"2, 3, 4, 5, 6,"},{"Start":"01:50.398 ","End":"01:52.465","Text":"7, 8, 9, 10, 11, 12."},{"Start":"01:52.465 ","End":"01:55.270","Text":"How would I do that? We\u0027ve seen previously, how we do it,"},{"Start":"01:55.270 ","End":"01:59.885","Text":"but we have a variable already called multiplier."},{"Start":"01:59.885 ","End":"02:05.155","Text":"We are going to start it at 1."},{"Start":"02:05.155 ","End":"02:09.005","Text":"We want it to keep going while it\u0027s"},{"Start":"02:09.005 ","End":"02:13.790","Text":"less than or equal to 12 because that\u0027s where we want it to go to."},{"Start":"02:13.790 ","End":"02:18.540","Text":"It\u0027s going to go up by 1 each time around the loop,"},{"Start":"02:18.540 ","End":"02:21.950","Text":"so we can just use the increment operator to do that."},{"Start":"02:21.950 ","End":"02:25.850","Text":"That\u0027s the initial part that we need to do."},{"Start":"02:25.850 ","End":"02:27.530","Text":"It says now in part c,"},{"Start":"02:27.530 ","End":"02:29.195","Text":"inside the for loop,"},{"Start":"02:29.195 ","End":"02:32.000","Text":"output the contents of the multiplier variable,"},{"Start":"02:32.000 ","End":"02:34.520","Text":"followed by the string x with spaces"},{"Start":"02:34.520 ","End":"02:37.205","Text":"either side followed by the contents of the table variable,"},{"Start":"02:37.205 ","End":"02:38.525","Text":"followed by the string,"},{"Start":"02:38.525 ","End":"02:40.460","Text":"and equals with spaces either sides,"},{"Start":"02:40.460 ","End":"02:42.230","Text":"so let\u0027s do that."},{"Start":"02:42.230 ","End":"02:45.365","Text":"We start off with the contents of the multiplier variable,"},{"Start":"02:45.365 ","End":"02:46.865","Text":"so I\u0027ll just put multiplier."},{"Start":"02:46.865 ","End":"02:48.905","Text":"Now, if I put plus here,"},{"Start":"02:48.905 ","End":"02:52.700","Text":"it will convert multiplier to a string when it prints it,"},{"Start":"02:52.700 ","End":"02:54.770","Text":"and it would join it to another string."},{"Start":"02:54.770 ","End":"02:59.600","Text":"In this case, it\u0027s the string space x with another space."},{"Start":"02:59.600 ","End":"03:02.240","Text":"Then I want to put the table variables,"},{"Start":"03:02.240 ","End":"03:04.955","Text":"so I\u0027d join it to the contents of the table variable."},{"Start":"03:04.955 ","End":"03:06.395","Text":"I\u0027m not adding numbers together,"},{"Start":"03:06.395 ","End":"03:08.425","Text":"I\u0027m joining strings together here."},{"Start":"03:08.425 ","End":"03:13.770","Text":"The next part is the string equals."},{"Start":"03:13.770 ","End":"03:16.580","Text":"I\u0027m just going to check at this point whether my code"},{"Start":"03:16.580 ","End":"03:19.480","Text":"throws up any errors and it has thrown up an error,"},{"Start":"03:19.480 ","End":"03:21.410","Text":"so let\u0027s have a look at what it is."},{"Start":"03:21.410 ","End":"03:29.045","Text":"Cannot find variable multiplier and It\u0027s because I\u0027ve put an I in the wrong place here."},{"Start":"03:29.045 ","End":"03:31.505","Text":"The variable I declared,"},{"Start":"03:31.505 ","End":"03:35.980","Text":"and the variable I was trying to use here were different, hence the error."},{"Start":"03:35.980 ","End":"03:39.740","Text":"That\u0027s good and that\u0027s why it\u0027s worth checking as you\u0027re going along for"},{"Start":"03:39.740 ","End":"03:44.360","Text":"any errors and to try not to have too many when you get to the end."},{"Start":"03:44.360 ","End":"03:46.700","Text":"It can become quite overwhelming if you\u0027ve got lots of errors,"},{"Start":"03:46.700 ","End":"03:48.560","Text":"you don\u0027t know where to start."},{"Start":"03:48.560 ","End":"03:51.125","Text":"That first part is done."},{"Start":"03:51.125 ","End":"03:55.520","Text":"Now it says in part d on the same line as the previous output."},{"Start":"03:55.520 ","End":"03:59.945","Text":"Output, the product of the multiplier and table variables."},{"Start":"03:59.945 ","End":"04:01.760","Text":"If I want to do it on the same line,"},{"Start":"04:01.760 ","End":"04:04.220","Text":"I don\u0027t use print line for this first part."},{"Start":"04:04.220 ","End":"04:05.915","Text":"I\u0027ll just use print,"},{"Start":"04:05.915 ","End":"04:09.680","Text":"that will not force the output onto a new line afterwards,"},{"Start":"04:09.680 ","End":"04:14.870","Text":"and so it will carry on printing from the last place it printed."},{"Start":"04:14.870 ","End":"04:19.610","Text":"But I actually do want to use print line on the next line because I want to force"},{"Start":"04:19.610 ","End":"04:22.340","Text":"a new line at the end of the output so that we"},{"Start":"04:22.340 ","End":"04:25.370","Text":"see the next line of the times table on a different line."},{"Start":"04:25.370 ","End":"04:27.050","Text":"If you just put print,"},{"Start":"04:27.050 ","End":"04:31.385","Text":"all your output would be on one line for the entire program and that\u0027s not what we want."},{"Start":"04:31.385 ","End":"04:34.265","Text":"Let\u0027s print line where the previous one is print."},{"Start":"04:34.265 ","End":"04:39.470","Text":"What we want here is the product of the multiplier and the table variables."},{"Start":"04:39.470 ","End":"04:45.825","Text":"So let\u0027s multiply them together using hashtag symbol which represents multiply,"},{"Start":"04:45.825 ","End":"04:49.290","Text":"and that should give us our result."},{"Start":"04:49.290 ","End":"04:51.050","Text":"That\u0027s us done in part e,"},{"Start":"04:51.050 ","End":"04:55.370","Text":"we were asked to test the method and check that the lines of"},{"Start":"04:55.370 ","End":"05:00.290","Text":"the sevenTimesTable are currently output all 12 lines and to correct any errors found."},{"Start":"05:00.290 ","End":"05:03.875","Text":"Hopefully, we won\u0027t have any errors and it\u0027s relatively straightforward."},{"Start":"05:03.875 ","End":"05:06.860","Text":"We\u0027ve already got rid of that one error we had previously."},{"Start":"05:06.860 ","End":"05:08.980","Text":"Now, let\u0027s have a go testing it."},{"Start":"05:08.980 ","End":"05:15.435","Text":"Sure enough, I see the sevenTimesTable pretty much as I would expect."},{"Start":"05:15.435 ","End":"05:22.410","Text":"If you\u0027ve had any errors I would imagine it\u0027s because you didn\u0027t calculate correctly."},{"Start":"05:22.410 ","End":"05:23.915","Text":"For some reason this was wrong,"},{"Start":"05:23.915 ","End":"05:26.000","Text":"or you didn\u0027t iterate correctly,"},{"Start":"05:26.000 ","End":"05:30.395","Text":"or just the way you output things weren\u0027t quite as it was expected."},{"Start":"05:30.395 ","End":"05:32.120","Text":"Just as to look at this again,"},{"Start":"05:32.120 ","End":"05:35.765","Text":"we first output the multiplier variable\u0027s contents,"},{"Start":"05:35.765 ","End":"05:39.440","Text":"then a literal string of an x with spaces either side,"},{"Start":"05:39.440 ","End":"05:42.244","Text":"then the contents of the table variable,"},{"Start":"05:42.244 ","End":"05:45.770","Text":"then a literal string with an equal sign with spaces."},{"Start":"05:45.770 ","End":"05:47.570","Text":"On the next part,"},{"Start":"05:47.570 ","End":"05:49.310","Text":"on this next statement here,"},{"Start":"05:49.310 ","End":"05:52.040","Text":"which will print on the same line as the previous one,"},{"Start":"05:52.040 ","End":"05:55.220","Text":"because print here and print line here,"},{"Start":"05:55.220 ","End":"05:56.960","Text":"when it does this calculation,"},{"Start":"05:56.960 ","End":"06:03.140","Text":"it will output it and then force the output onto a new line for any subsequent output."},{"Start":"06:03.140 ","End":"06:04.565","Text":"I hope that makes sense."},{"Start":"06:04.565 ","End":"06:08.010","Text":"That\u0027s it for this one. I\u0027ll see you in the next one."}],"ID":28026},{"Watched":false,"Name":"Exercise 4","Duration":"8m 44s","ChapterTopicVideoID":26939,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.093","Text":"Hello again. In this exercise,"},{"Start":"00:02.093 ","End":"00:04.035","Text":"we\u0027ve been asked to create a new method called"},{"Start":"00:04.035 ","End":"00:08.250","Text":"allTimesTable and within there to create an integer variable called"},{"Start":"00:08.250 ","End":"00:10.380","Text":"table with no initial value and"},{"Start":"00:10.380 ","End":"00:14.820","Text":"a second integer variable called multiplier again with no initial value."},{"Start":"00:14.820 ","End":"00:19.155","Text":"In Part b, we\u0027re asked to create a pair of nested for loops,"},{"Start":"00:19.155 ","End":"00:22.380","Text":"both of which it\u0027s right between 1 and 12."},{"Start":"00:22.380 ","End":"00:25.080","Text":"The inner loop should iterate multiplier,"},{"Start":"00:25.080 ","End":"00:27.915","Text":"and the outer loop should iterate table."},{"Start":"00:27.915 ","End":"00:30.060","Text":"At the appropriate point in the code,"},{"Start":"00:30.060 ","End":"00:34.200","Text":"we\u0027re asked to output the contents of the multiplier variable followed by"},{"Start":"00:34.200 ","End":"00:39.450","Text":"the string \" x \" followed by the contents of the table variable,"},{"Start":"00:39.450 ","End":"00:44.690","Text":"followed by the string \" = \"."},{"Start":"00:44.690 ","End":"00:47.117","Text":"On the same line as the previous output,"},{"Start":"00:47.117 ","End":"00:52.325","Text":"we\u0027re asked in Part d to output the product of the multiplier and table variables."},{"Start":"00:52.325 ","End":"00:54.410","Text":"In Part e, we\u0027re asked to check that"},{"Start":"00:54.410 ","End":"00:57.880","Text":"the unlimited buffering option is ticked in the terminal window of BlueJ,"},{"Start":"00:57.880 ","End":"01:02.390","Text":"and then to test the method by creating an object on the workbench and checking that"},{"Start":"01:02.390 ","End":"01:08.285","Text":"all 12 lines of the 1 times table to the 12 times table are correctly output,"},{"Start":"01:08.285 ","End":"01:10.910","Text":"and that\u0027s 144 lines in total."},{"Start":"01:10.910 ","End":"01:14.120","Text":"You are asked to then correct any errors found in."},{"Start":"01:14.120 ","End":"01:16.700","Text":"in Part f at an appropriate point in the code,"},{"Start":"01:16.700 ","End":"01:18.770","Text":"we\u0027re asked to output the contents of"},{"Start":"01:18.770 ","End":"01:22.959","Text":"the table variable followed by the string times table"},{"Start":"01:22.959 ","End":"01:25.670","Text":": so that each table is proceeded by"},{"Start":"01:25.670 ","End":"01:30.410","Text":"a heading indicating which times table is being output."},{"Start":"01:30.410 ","End":"01:36.715","Text":"Let\u0027s go ahead and create the new method called allTimesTable()."},{"Start":"01:36.715 ","End":"01:40.565","Text":"Because in the first part I need the same variables as previously,"},{"Start":"01:40.565 ","End":"01:44.960","Text":"I\u0027m just going to copy that to save myself typing those again."},{"Start":"01:44.960 ","End":"01:49.280","Text":"I make sure I close off my method and change this name,"},{"Start":"01:49.280 ","End":"01:52.326","Text":"so this is called allTimesTables()."},{"Start":"01:52.326 ","End":"01:54.425","Text":"I don\u0027t need initial values,"},{"Start":"01:54.425 ","End":"01:58.130","Text":"it tells me in Part a for table or multiplier."},{"Start":"01:58.130 ","End":"02:00.605","Text":"Now I\u0027m ready for Part b."},{"Start":"02:00.605 ","End":"02:03.235","Text":"Now we\u0027re going to do something slightly different."},{"Start":"02:03.235 ","End":"02:07.378","Text":"We are going to create a pair of nested loop,"},{"Start":"02:07.378 ","End":"02:10.325","Text":"so one loop inside another loop."},{"Start":"02:10.325 ","End":"02:18.710","Text":"The first one is used to iterate multiplier and the outer loop iterates tables,"},{"Start":"02:18.710 ","End":"02:22.355","Text":"so let\u0027s do it outside and then the inside."},{"Start":"02:22.355 ","End":"02:24.290","Text":"Outer loop should iterate table,"},{"Start":"02:24.290 ","End":"02:30.180","Text":"so table is going to take on the values 1-12."},{"Start":"02:30.180 ","End":"02:32.250","Text":"So table equals 1."},{"Start":"02:32.250 ","End":"02:36.405","Text":"Table is less than or equal to 12."},{"Start":"02:36.405 ","End":"02:40.290","Text":"Table++ will increment to the next value."},{"Start":"02:40.290 ","End":"02:45.410","Text":"That\u0027s my outer loop and I\u0027m going to need another loop inside it,"},{"Start":"02:45.410 ","End":"02:49.130","Text":"so I\u0027m going to indent and then start another for-loop."},{"Start":"02:49.130 ","End":"02:52.681","Text":"This time I\u0027m iterating multiplier,"},{"Start":"02:52.681 ","End":"02:57.530","Text":"and again I\u0027m going between the values of 1 and 12."},{"Start":"02:57.530 ","End":"03:00.620","Text":"Multiplier should be less than or equal to 12,"},{"Start":"03:00.620 ","End":"03:05.750","Text":"and then I do multiplier++."},{"Start":"03:05.750 ","End":"03:09.920","Text":"I need a pair of brackets there as well because that will contain"},{"Start":"03:09.920 ","End":"03:15.075","Text":"whatever operations I want to do inside the inner loop."},{"Start":"03:15.075 ","End":"03:17.405","Text":"There is Part b done."},{"Start":"03:17.405 ","End":"03:21.665","Text":"I\u0027ve created a pair of nested loops and they iterate between 1 and 12."},{"Start":"03:21.665 ","End":"03:24.494","Text":"The inner loop is iterating multiplier,"},{"Start":"03:24.494 ","End":"03:27.790","Text":"the outer loop is iterating table."},{"Start":"03:27.790 ","End":"03:30.555","Text":"Now Part c at the appropriate point in the code,"},{"Start":"03:30.555 ","End":"03:34.130","Text":"output the contents of the multiplier variable followed by a string x,"},{"Start":"03:34.130 ","End":"03:35.450","Text":"followed by the contents of the table,"},{"Start":"03:35.450 ","End":"03:38.450","Text":"followed by the string equals just like we did last time."},{"Start":"03:38.450 ","End":"03:42.350","Text":"The appropriate point in the code we are supposed to choose naturally go here."},{"Start":"03:42.350 ","End":"03:45.260","Text":"Should it go here outside the method itself?"},{"Start":"03:45.260 ","End":"03:50.510","Text":"Well, if we want to do every line of every times table,"},{"Start":"03:50.510 ","End":"03:53.180","Text":"the only line that\u0027s going to do that for"},{"Start":"03:53.180 ","End":"03:56.255","Text":"us is this one here in the middle of the inner loop."},{"Start":"03:56.255 ","End":"03:57.800","Text":"This inner loop is going to run"},{"Start":"03:57.800 ","End":"04:04.530","Text":"144 times the line inside because it will run 12 times here,"},{"Start":"04:04.530 ","End":"04:10.310","Text":"and then times 12 overall because of this outer loop."},{"Start":"04:10.310 ","End":"04:15.260","Text":"The inner loop will run 12 times but the outer loop runs 12 times as well,"},{"Start":"04:15.260 ","End":"04:19.915","Text":"and that means this one line here is going to run 144 times."},{"Start":"04:19.915 ","End":"04:25.419","Text":"The output is as we had before,"},{"Start":"04:25.419 ","End":"04:27.495","Text":"so let me type it out;"},{"Start":"04:27.495 ","End":"04:36.296","Text":"System.out.println and we want the multiplier variable followed by the string x,"},{"Start":"04:36.296 ","End":"04:41.615","Text":"followed by the contents of the table variable,"},{"Start":"04:41.615 ","End":"04:46.855","Text":"followed by the string = just as we had in that previous exercise."},{"Start":"04:46.855 ","End":"04:48.010","Text":"There\u0027s the first line,"},{"Start":"04:48.010 ","End":"04:50.960","Text":"and then it says on the same line as"},{"Start":"04:50.960 ","End":"04:54.830","Text":"the previous output products of the multiplier and table variables."},{"Start":"04:54.830 ","End":"04:57.209","Text":"Again, we need to remove the ln here,"},{"Start":"04:57.209 ","End":"04:59.334","Text":"so we don\u0027t want to force it onto a new line."},{"Start":"04:59.334 ","End":"05:01.115","Text":"We want to keep it on the same line,"},{"Start":"05:01.115 ","End":"05:05.270","Text":"but the next line we do want to force a line break at the end."},{"Start":"05:05.270 ","End":"05:08.930","Text":"So we put print line and the output is going to"},{"Start":"05:08.930 ","End":"05:14.370","Text":"be just as it was before multiplier times table,"},{"Start":"05:14.370 ","End":"05:19.160","Text":"but this time the table value will be changing and it won\u0027t be"},{"Start":"05:19.160 ","End":"05:25.500","Text":"7 all the time as it was in the previous exercise because it\u0027s writing through 1-12 here."},{"Start":"05:25.760 ","End":"05:31.260","Text":"That\u0027s it, I\u0027ll compile and I don\u0027t have any errors."},{"Start":"05:31.260 ","End":"05:35.930","Text":"It does say to check the terminal window because what happens with"},{"Start":"05:35.930 ","End":"05:41.075","Text":"the BlueJ terminal is if you don\u0027t have this option turned on unlimited buffering,"},{"Start":"05:41.075 ","End":"05:45.440","Text":"it will only display a certain number of lines in this display and you will"},{"Start":"05:45.440 ","End":"05:50.435","Text":"lose some of the earlier output because we\u0027re outputting 144 lines here."},{"Start":"05:50.435 ","End":"05:52.580","Text":"You just won\u0027t see the early ones and you\u0027ll think"},{"Start":"05:52.580 ","End":"05:55.385","Text":"your code hasn\u0027t worked when it in fact it has."},{"Start":"05:55.385 ","End":"06:00.530","Text":"Let\u0027s see if that works now because we did have our Unlimited buffering ticked."},{"Start":"06:00.530 ","End":"06:04.685","Text":"We now need to create an object and then we\u0027ll run"},{"Start":"06:04.685 ","End":"06:08.690","Text":"allTimesTable() method in it. There we go."},{"Start":"06:08.690 ","End":"06:10.010","Text":"If I scroll up and down,"},{"Start":"06:10.010 ","End":"06:12.920","Text":"there is a scroll bar here in the terminal window in BlueJ."},{"Start":"06:12.920 ","End":"06:18.016","Text":"I can see that I\u0027ve got all of the times tables: the 1 times table,"},{"Start":"06:18.016 ","End":"06:19.430","Text":"2 times table,"},{"Start":"06:19.430 ","End":"06:20.510","Text":"3 times table,"},{"Start":"06:20.510 ","End":"06:27.530","Text":"and so on all the way up to the 12 times table."},{"Start":"06:27.530 ","End":"06:31.770","Text":"For part of the exercise f we"},{"Start":"06:31.770 ","End":"06:36.590","Text":"are asked at an appropriate point in the code to output the contents of"},{"Start":"06:36.590 ","End":"06:40.835","Text":"the table variable followed by the string times tables so that"},{"Start":"06:40.835 ","End":"06:46.055","Text":"each table is proceeded by a heading indicating which timetable has been output."},{"Start":"06:46.055 ","End":"06:50.825","Text":"Here we see that 11 times table has ended here and the 12 times table start."},{"Start":"06:50.825 ","End":"06:52.805","Text":"It would be nice to have a heading above"},{"Start":"06:52.805 ","End":"06:56.630","Text":"each table so we know which one is just about to be printed."},{"Start":"06:56.630 ","End":"07:00.995","Text":"Where would be the appropriate place to put that?"},{"Start":"07:00.995 ","End":"07:08.600","Text":"Well, each time the table changes we want to output the new table,"},{"Start":"07:08.600 ","End":"07:13.250","Text":"and so here would seem to be a sensible place for it to be output."},{"Start":"07:13.250 ","End":"07:14.546","Text":"It definitely wouldn\u0027t go in here,"},{"Start":"07:14.546 ","End":"07:18.710","Text":"otherwise against every line we\u0027d be printing what times table we\u0027re printing."},{"Start":"07:18.710 ","End":"07:24.995","Text":"We just want to do it once every time a new value of table is taken on."},{"Start":"07:24.995 ","End":"07:28.580","Text":"What we\u0027ll do is do it here;"},{"Start":"07:28.580 ","End":"07:35.750","Text":"System.out.println and I do want println because I want a new line to start afterwards."},{"Start":"07:35.750 ","End":"07:39.245","Text":"I\u0027m going to print the content of the table variable,"},{"Start":"07:39.245 ","End":"07:45.230","Text":"followed by the string times table with a colon on the end,"},{"Start":"07:45.230 ","End":"07:49.820","Text":"and let\u0027s see how the output changes for that."},{"Start":"07:49.820 ","End":"07:52.490","Text":"Hopefully, it\u0027ll be a little bit more easy to follow"},{"Start":"07:52.490 ","End":"07:55.655","Text":"in the terminal window when we looked at it."},{"Start":"07:55.655 ","End":"07:59.300","Text":"There we go, it has shown us ahead of each table."},{"Start":"07:59.300 ","End":"08:00.757","Text":"You\u0027ve got the 1 times table,"},{"Start":"08:00.757 ","End":"08:02.060","Text":"2 times table, 3 times table,"},{"Start":"08:02.060 ","End":"08:05.405","Text":"and so on all the way up to 12."},{"Start":"08:05.405 ","End":"08:08.210","Text":"That was again pretty straightforward,"},{"Start":"08:08.210 ","End":"08:10.820","Text":"more complex in the sense that you had to have"},{"Start":"08:10.820 ","End":"08:14.603","Text":"a nested loop and understanding what nested loop is first of all,"},{"Start":"08:14.603 ","End":"08:18.230","Text":"but also how you\u0027ve got to place lines at"},{"Start":"08:18.230 ","End":"08:22.295","Text":"the appropriate place in either the inner loop,"},{"Start":"08:22.295 ","End":"08:23.960","Text":"or the outer loop,"},{"Start":"08:23.960 ","End":"08:25.730","Text":"or even outside both loops."},{"Start":"08:25.730 ","End":"08:30.080","Text":"I could have had a message here saying end of program if I wanted to,"},{"Start":"08:30.080 ","End":"08:31.970","Text":"and it would only ever print that once."},{"Start":"08:31.970 ","End":"08:35.884","Text":"Maybe it\u0027s going to be a little bit time of messing around changing"},{"Start":"08:35.884 ","End":"08:40.221","Text":"the output and just see the effect of the placement of your line,"},{"Start":"08:40.221 ","End":"08:45.120","Text":"what it would be on the program. See you for the next one."}],"ID":28027},{"Watched":false,"Name":"Exercise 5","Duration":"9m 34s","ChapterTopicVideoID":26931,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:01.185","Text":"Hi everyone."},{"Start":"00:01.185 ","End":"00:02.310","Text":"In this exercise,"},{"Start":"00:02.310 ","End":"00:05.310","Text":"we\u0027ve been asked to create a new method called whileCount,"},{"Start":"00:05.310 ","End":"00:06.705","Text":"and in Part a,"},{"Start":"00:06.705 ","End":"00:11.985","Text":"we\u0027ve been told to use a while loop and output the numbers from 1-10."},{"Start":"00:11.985 ","End":"00:14.565","Text":"In Part b, we\u0027re asked to test the method."},{"Start":"00:14.565 ","End":"00:18.525","Text":"If it continues producing output past 10 or appears to have crashed,"},{"Start":"00:18.525 ","End":"00:19.770","Text":"we\u0027re told to click on"},{"Start":"00:19.770 ","End":"00:22.170","Text":"the \"Reset virtual machine\" icon in"},{"Start":"00:22.170 ","End":"00:25.350","Text":"the bottom right corner of the BlueJ application window."},{"Start":"00:25.350 ","End":"00:28.215","Text":"Then to correct any errors found."},{"Start":"00:28.215 ","End":"00:30.710","Text":"In Part c, in the same method,"},{"Start":"00:30.710 ","End":"00:33.725","Text":"we are asked to add another while loop after the previous one,"},{"Start":"00:33.725 ","End":"00:38.485","Text":"which outputs the numbers from 10-100 in steps of 10."},{"Start":"00:38.485 ","End":"00:41.280","Text":"In Part d, we\u0027re asked to test again."},{"Start":"00:41.280 ","End":"00:45.410","Text":"If it continues producing output past 100 or appears to have crashed,"},{"Start":"00:45.410 ","End":"00:46.640","Text":"again we can click on"},{"Start":"00:46.640 ","End":"00:51.870","Text":"the \"Reset virtual machine\" icon in BlueJ to reset the virtual machine,"},{"Start":"00:51.870 ","End":"00:54.475","Text":"and then we can correct any errors found."},{"Start":"00:54.475 ","End":"00:56.930","Text":"In Part e, in the same method we are"},{"Start":"00:56.930 ","End":"00:59.555","Text":"asked to add another while loop after the previous one,"},{"Start":"00:59.555 ","End":"01:07.330","Text":"which outputs the numbers from 2,020 to minus 5,000 in steps of minus 100."},{"Start":"01:07.330 ","End":"01:09.120","Text":"Finally, in Part f,"},{"Start":"01:09.120 ","End":"01:10.935","Text":"we\u0027re asked to test again."},{"Start":"01:10.935 ","End":"01:16.100","Text":"If it continues producing the output past minus 5,000 or appears to have crashed,"},{"Start":"01:16.100 ","End":"01:21.530","Text":"once more we can reset BlueJ using the virtual machine reset icon,"},{"Start":"01:21.530 ","End":"01:24.710","Text":"and then we can correct any errors found."},{"Start":"01:24.710 ","End":"01:29.060","Text":"Let\u0027s now create a method called whileCount,"},{"Start":"01:29.060 ","End":"01:32.075","Text":"after all the existing methods."},{"Start":"01:32.075 ","End":"01:34.355","Text":"This time we\u0027re going to be using"},{"Start":"01:34.355 ","End":"01:38.540","Text":"a while loop rather than a for loop that we\u0027ve been using before."},{"Start":"01:38.540 ","End":"01:42.919","Text":"But the exercise is very familiar from the initial for-loop exercises,"},{"Start":"01:42.919 ","End":"01:47.585","Text":"so let\u0027s see what the difference is in syntax and operation of a while loop."},{"Start":"01:47.585 ","End":"01:50.405","Text":"We\u0027re going to output the numbers 1-10 in Part a."},{"Start":"01:50.405 ","End":"01:52.925","Text":"Let\u0027s start with the keyword \"while\"."},{"Start":"01:52.925 ","End":"01:57.560","Text":"Now for while, all we need is a Boolean condition inside"},{"Start":"01:57.560 ","End":"02:04.755","Text":"the brackets that determines when while loop is going to stop executing."},{"Start":"02:04.755 ","End":"02:09.365","Text":"We\u0027ll need a variable to hold the number,"},{"Start":"02:09.365 ","End":"02:13.710","Text":"so let\u0027s call it i. It\u0027s nice and short."},{"Start":"02:13.710 ","End":"02:15.650","Text":"i usually stands for index by the way,"},{"Start":"02:15.650 ","End":"02:17.780","Text":"which we\u0027ll come across very soon."},{"Start":"02:17.780 ","End":"02:22.045","Text":"But if you wonder why everyone uses i as their variable name,"},{"Start":"02:22.045 ","End":"02:23.515","Text":"it\u0027s nice and short,"},{"Start":"02:23.515 ","End":"02:27.035","Text":"and there\u0027s often a case for a variable called an index variable."},{"Start":"02:27.035 ","End":"02:29.360","Text":"Let\u0027s just call it as i,"},{"Start":"02:29.360 ","End":"02:32.270","Text":"and we want to start 1 rather than 0."},{"Start":"02:32.270 ","End":"02:34.760","Text":"Let\u0027s change that initial value to 1."},{"Start":"02:34.760 ","End":"02:39.670","Text":"While i is less than or equal to 10,"},{"Start":"02:39.670 ","End":"02:43.424","Text":"we want to keep our loop executing."},{"Start":"02:43.424 ","End":"02:49.830","Text":"The syntax in this first line is actually much simpler than for the for-loop,"},{"Start":"02:49.830 ","End":"02:56.940","Text":"because all we need to do is say what the termination condition is going to be."},{"Start":"02:59.150 ","End":"03:04.085","Text":"Inside is exactly as it would have been for the for-loop."},{"Start":"03:04.085 ","End":"03:06.500","Text":"On the surface it looks easier,"},{"Start":"03:06.500 ","End":"03:09.740","Text":"but there\u0027s one thing we do need to do with a while-loop,"},{"Start":"03:09.740 ","End":"03:15.275","Text":"which is to make sure that this clause here can ever actually terminate."},{"Start":"03:15.275 ","End":"03:20.285","Text":"With a for-loop it takes care of the incrementing of the variable that you\u0027re using."},{"Start":"03:20.285 ","End":"03:22.160","Text":"But this could be anything in here,"},{"Start":"03:22.160 ","End":"03:27.770","Text":"so we\u0027ve got to be responsible for making sure that this condition is actually possible."},{"Start":"03:27.770 ","End":"03:30.185","Text":"Now if i is 1 and never is changed,"},{"Start":"03:30.185 ","End":"03:32.000","Text":"then this will run forever."},{"Start":"03:32.000 ","End":"03:33.575","Text":"This will be an infinite loop."},{"Start":"03:33.575 ","End":"03:35.818","Text":"We do actually need to do something,"},{"Start":"03:35.818 ","End":"03:38.465","Text":"and really it\u0027s as simple as incrementing i,"},{"Start":"03:38.465 ","End":"03:43.910","Text":"so that each time around the loop i takes on a new value until it reaches 10,"},{"Start":"03:43.910 ","End":"03:46.970","Text":"and then the program will cease execution."},{"Start":"03:46.970 ","End":"03:51.380","Text":"I\u0027ll compile that just to check my syntax is correct,"},{"Start":"03:51.380 ","End":"03:52.994","Text":"which it does seem to be."},{"Start":"03:52.994 ","End":"03:58.775","Text":"It says then to test if it continues producing output past 10 or appears to have crashed,"},{"Start":"03:58.775 ","End":"04:03.290","Text":"you can click on the \"Reset virtual machine\" icon and correct any errors."},{"Start":"04:03.290 ","End":"04:06.125","Text":"Let\u0027s see what mine does."},{"Start":"04:06.125 ","End":"04:10.205","Text":"I\u0027ll create my object and execute the method,"},{"Start":"04:10.205 ","End":"04:12.190","Text":"which is called whileCount."},{"Start":"04:12.190 ","End":"04:14.239","Text":"It seems to work, no problem."},{"Start":"04:14.239 ","End":"04:18.725","Text":"No need to hit the \"Reset\" button, which is over here."},{"Start":"04:18.725 ","End":"04:20.815","Text":"If I hover over it you\u0027ll see it appears,"},{"Start":"04:20.815 ","End":"04:22.605","Text":"\"Reset Java Virtual Machine\"."},{"Start":"04:22.605 ","End":"04:24.410","Text":"That will stop the program running."},{"Start":"04:24.410 ","End":"04:27.260","Text":"If I had an infinite loop I\u0027d have to wait an awful long time"},{"Start":"04:27.260 ","End":"04:31.280","Text":"potentially for it to wrap around to 0 again,"},{"Start":"04:31.280 ","End":"04:33.725","Text":"and maybe I\u0027d hit what I\u0027m looking for."},{"Start":"04:33.725 ","End":"04:36.140","Text":"But I\u0027ve got it right, so I don\u0027t need to do that."},{"Start":"04:36.140 ","End":"04:38.660","Text":"Let\u0027s move on to Part c in"},{"Start":"04:38.660 ","End":"04:42.140","Text":"the same method to add another while loop after the previous one,"},{"Start":"04:42.140 ","End":"04:46.430","Text":"which outputs the numbers from 10-100 in steps of 10."},{"Start":"04:46.430 ","End":"04:48.170","Text":"I\u0027m not going to create a new method,"},{"Start":"04:48.170 ","End":"04:50.900","Text":"I\u0027m going to do it inside the existing one."},{"Start":"04:50.900 ","End":"04:56.670","Text":"I want it to go now up to 100 in steps of 10."},{"Start":"04:56.670 ","End":"05:00.765","Text":"This time i is going to be less than or equal to 100."},{"Start":"05:00.765 ","End":"05:07.020","Text":"The inside of the loop is still going to output the value of i,"},{"Start":"05:07.020 ","End":"05:09.455","Text":"because I don\u0027t need to output something."},{"Start":"05:09.455 ","End":"05:12.455","Text":"But now instead of adding 1 to y,"},{"Start":"05:12.455 ","End":"05:13.700","Text":"I need to add 10."},{"Start":"05:13.700 ","End":"05:16.700","Text":"Let\u0027s try and use the compound operator."},{"Start":"05:16.700 ","End":"05:18.665","Text":"You remember it\u0027s just saying,"},{"Start":"05:18.665 ","End":"05:24.464","Text":"I\u0027m going to assign something and I\u0027m going to add to it before I do the assignment."},{"Start":"05:24.464 ","End":"05:28.850","Text":"This will have the equivalent effect of i equals i plus 10."},{"Start":"05:28.850 ","End":"05:34.245","Text":"This will go up to 100 in steps of 10, or it would,"},{"Start":"05:34.245 ","End":"05:40.050","Text":"but actually I need to make sure I\u0027ve set the value of i to what I need it to be here."},{"Start":"05:40.050 ","End":"05:41.860","Text":"I\u0027m starting at 10,"},{"Start":"05:41.860 ","End":"05:44.660","Text":"so I need to be responsible with setting"},{"Start":"05:44.660 ","End":"05:48.890","Text":"i\u0027s initial value before we even go into the loop."},{"Start":"05:48.890 ","End":"05:56.235","Text":"Let\u0027s have a go at that and see if I do get output from 10-100 in steps of 10,"},{"Start":"05:56.235 ","End":"05:58.250","Text":"and if not, we\u0027ll fix it."},{"Start":"05:58.250 ","End":"06:00.350","Text":"It\u0027s still got the previous output."},{"Start":"06:00.350 ","End":"06:02.330","Text":"There\u0027s 1, 2, 3, 4, 5, 6, 7, 8,"},{"Start":"06:02.330 ","End":"06:04.565","Text":"9, 10, from the first part of the program."},{"Start":"06:04.565 ","End":"06:06.440","Text":"Then the second part, 10, 20,"},{"Start":"06:06.440 ","End":"06:09.365","Text":"30, and so on, up to 100,"},{"Start":"06:09.365 ","End":"06:15.319","Text":"so that seems to have done what I need to for Part c. Let\u0027s look at Part e then,"},{"Start":"06:15.319 ","End":"06:18.890","Text":"in the same method add another while-loop after the previous ones,"},{"Start":"06:18.890 ","End":"06:26.005","Text":"which outputs the numbers from 2,020 to minus 5,000 in steps of minus 100."},{"Start":"06:26.005 ","End":"06:28.325","Text":"Why those strange numbers?"},{"Start":"06:28.325 ","End":"06:30.740","Text":"Well actually they could represent years, couldn\u0027t they?"},{"Start":"06:30.740 ","End":"06:33.605","Text":"We could be doing a timeline of some sort,"},{"Start":"06:33.605 ","End":"06:36.005","Text":"going back to BC times."},{"Start":"06:36.005 ","End":"06:37.940","Text":"Let\u0027s go ahead and do that."},{"Start":"06:37.940 ","End":"06:43.025","Text":"We start with our initial value of 2,020 potentially,"},{"Start":"06:43.025 ","End":"06:47.460","Text":"and then we want to go down in steps of minus 100."},{"Start":"06:47.460 ","End":"06:50.675","Text":"It\u0027s going to be very similar to before,"},{"Start":"06:50.675 ","End":"06:57.485","Text":"but this time we want to check that i becomes a smaller number than minus 5,000,"},{"Start":"06:57.485 ","End":"07:00.290","Text":"we will want to terminate the loop."},{"Start":"07:00.290 ","End":"07:03.440","Text":"When it goes to minus 5,100,"},{"Start":"07:03.440 ","End":"07:05.435","Text":"we should have stopped before that point."},{"Start":"07:05.435 ","End":"07:10.170","Text":"We\u0027ll produce our output as ever."},{"Start":"07:10.170 ","End":"07:14.615","Text":"This time we need to decrement by 100 each time."},{"Start":"07:14.615 ","End":"07:20.380","Text":"I\u0027m going to try and use the compound assignment operator again."},{"Start":"07:20.380 ","End":"07:26.029","Text":"Minus equals 100 means take 100 off i each time."},{"Start":"07:26.029 ","End":"07:27.755","Text":"The order is important by the way,"},{"Start":"07:27.755 ","End":"07:29.810","Text":"if I put equals minus 100,"},{"Start":"07:29.810 ","End":"07:34.565","Text":"it would just replace the contents of i with minus 100 every time around the loop."},{"Start":"07:34.565 ","End":"07:36.490","Text":"So this will become an infinite loop."},{"Start":"07:36.490 ","End":"07:44.605","Text":"What I\u0027m interested in doing is taking 100 off and assigning the results into i."},{"Start":"07:44.605 ","End":"07:49.275","Text":"Let\u0027s see for Part f then if that works."},{"Start":"07:49.275 ","End":"07:52.335","Text":"Compile it first, no errors."},{"Start":"07:52.335 ","End":"07:55.230","Text":"Let\u0027s then run it."},{"Start":"07:55.230 ","End":"07:57.945","Text":"I should see 3 sets of output now."},{"Start":"07:57.945 ","End":"08:00.120","Text":"Last one is very long,"},{"Start":"08:00.120 ","End":"08:02.040","Text":"so let me scroll up and check it."},{"Start":"08:02.040 ","End":"08:03.150","Text":"I\u0027ve still got my 1-10,"},{"Start":"08:03.150 ","End":"08:04.805","Text":"I\u0027ve still got my 10-100."},{"Start":"08:04.805 ","End":"08:07.145","Text":"Then I\u0027ve got this new output here,"},{"Start":"08:07.145 ","End":"08:08.700","Text":"where it goes 2,020,"},{"Start":"08:08.700 ","End":"08:10.420","Text":"1,920, 1,820,"},{"Start":"08:10.420 ","End":"08:13.730","Text":"and so on, goes down to the 0,"},{"Start":"08:13.730 ","End":"08:19.265","Text":"and then it goes below 0 up to minus,"},{"Start":"08:19.265 ","End":"08:21.990","Text":"interesting, 4,980,"},{"Start":"08:21.990 ","End":"08:23.130","Text":"so what\u0027s happened here?"},{"Start":"08:23.130 ","End":"08:27.995","Text":"What I\u0027ve been doing is I\u0027ve been taking 100 off,"},{"Start":"08:27.995 ","End":"08:29.591","Text":"and that\u0027s correct,"},{"Start":"08:29.591 ","End":"08:31.805","Text":"and I started in 20s,"},{"Start":"08:31.805 ","End":"08:34.670","Text":"so it would indeed finish up minus 4,980,"},{"Start":"08:34.670 ","End":"08:36.620","Text":"that\u0027s exactly what I\u0027d expect."},{"Start":"08:36.620 ","End":"08:39.020","Text":"It\u0027s doing exactly what it should do."},{"Start":"08:39.020 ","End":"08:40.955","Text":"It\u0027s taking 100 off each time,"},{"Start":"08:40.955 ","End":"08:43.430","Text":"but it\u0027s not finishing on minus 5,000,"},{"Start":"08:43.430 ","End":"08:45.485","Text":"it\u0027s finishing on minus 4,980,"},{"Start":"08:45.485 ","End":"08:50.180","Text":"because if I take another 100 off it would take me below minus 5,000."},{"Start":"08:50.180 ","End":"08:52.955","Text":"If I started at exactly 2,000,"},{"Start":"08:52.955 ","End":"08:55.370","Text":"it would hit 5,000 exactly as well."},{"Start":"08:55.370 ","End":"08:57.695","Text":"But I started at 2,020."},{"Start":"08:57.695 ","End":"09:00.930","Text":"That works as I would expect it to,"},{"Start":"09:00.930 ","End":"09:02.930","Text":"although initially I was thinking, \"Oh, does that work?\""},{"Start":"09:02.930 ","End":"09:06.125","Text":"Yes, it does, it\u0027s just the numbers that we\u0027ve used."},{"Start":"09:06.125 ","End":"09:08.330","Text":"That\u0027s it for this exercise,"},{"Start":"09:08.330 ","End":"09:11.030","Text":"where we looked at using a while-loop to"},{"Start":"09:11.030 ","End":"09:14.090","Text":"do what we were doing previously with a for-loop,"},{"Start":"09:14.090 ","End":"09:18.305","Text":"the difference being you\u0027re responsible for maintaining"},{"Start":"09:18.305 ","End":"09:23.495","Text":"the variables inside the loop that you\u0027re going to use to break out the loop."},{"Start":"09:23.495 ","End":"09:25.760","Text":"In my case it was always a number,"},{"Start":"09:25.760 ","End":"09:27.650","Text":"but it could be something else,"},{"Start":"09:27.650 ","End":"09:29.165","Text":"or it could be a combination of things."},{"Start":"09:29.165 ","End":"09:32.010","Text":"That\u0027s what we\u0027ll look at in the subsequent exercises."},{"Start":"09:32.010 ","End":"09:34.969","Text":"I\u0027ll see you shortly for those."}],"ID":28028},{"Watched":false,"Name":"Exercise 6","Duration":"5m 11s","ChapterTopicVideoID":26932,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.740 ","End":"00:04.290","Text":"Hello, welcome back. In this next exercise,"},{"Start":"00:04.290 ","End":"00:07.320","Text":"we\u0027ve been asked to create a new method called Fibonacci."},{"Start":"00:07.320 ","End":"00:11.190","Text":"Within it, we\u0027ve been asked to declare and initialize a number of variables,"},{"Start":"00:11.190 ","End":"00:13.500","Text":"num1 with a value 0,"},{"Start":"00:13.500 ","End":"00:15.570","Text":"num2 with the value 1,"},{"Start":"00:15.570 ","End":"00:17.744","Text":"limit with the value 12,"},{"Start":"00:17.744 ","End":"00:20.130","Text":"temp with the value 0,"},{"Start":"00:20.130 ","End":"00:23.010","Text":"and term with the value 0."},{"Start":"00:23.010 ","End":"00:26.865","Text":"In part b, we\u0027re then asked to use a while loop to iterate"},{"Start":"00:26.865 ","End":"00:31.214","Text":"while term is less than or equal to limit."},{"Start":"00:31.214 ","End":"00:32.610","Text":"In part c,"},{"Start":"00:32.610 ","End":"00:38.210","Text":"we\u0027re asked inside the loop to output num1 assigned to temp,"},{"Start":"00:38.210 ","End":"00:42.530","Text":"the sum of num1 and num2 assigned to num1,"},{"Start":"00:42.530 ","End":"00:44.345","Text":"the contents of num2,"},{"Start":"00:44.345 ","End":"00:47.885","Text":"assign to num2 the contents of temp,"},{"Start":"00:47.885 ","End":"00:50.750","Text":"and then to increment the term variable."},{"Start":"00:50.750 ","End":"00:55.850","Text":"In part d, we\u0027re asked to test the method outputs the Fibonacci sequence,"},{"Start":"00:55.850 ","End":"00:57.605","Text":"this series of numbers here."},{"Start":"00:57.605 ","End":"01:02.690","Text":"Let\u0027s go ahead and create a method called Fibonacci."},{"Start":"01:02.690 ","End":"01:08.735","Text":"We\u0027ve initially been asked to assign values to various variables and create them."},{"Start":"01:08.735 ","End":"01:16.205","Text":"They all seem to be integers so we can do that in one line, num1 is 0,"},{"Start":"01:16.205 ","End":"01:19.085","Text":"num2 is 1,"},{"Start":"01:19.085 ","End":"01:22.130","Text":"limit is 12,"},{"Start":"01:22.130 ","End":"01:24.275","Text":"temp is 0,"},{"Start":"01:24.275 ","End":"01:28.390","Text":"and term is 0."},{"Start":"01:28.390 ","End":"01:31.070","Text":"That\u0027s great."},{"Start":"01:31.070 ","End":"01:34.190","Text":"The next part is to use a while loop to"},{"Start":"01:34.190 ","End":"01:40.290","Text":"iterate while term is less than or equal to limit."},{"Start":"01:40.360 ","End":"01:42.830","Text":"That\u0027s pretty straightforward."},{"Start":"01:42.830 ","End":"01:46.190","Text":"Term is less than or equal to limit,"},{"Start":"01:46.190 ","End":"01:53.370","Text":"as long as that is true the inside of this loop is going to keep ongoing."},{"Start":"01:53.390 ","End":"01:56.100","Text":"Then inside the loop in part c,"},{"Start":"01:56.100 ","End":"01:57.680","Text":"we\u0027ve asked to do a number of things."},{"Start":"01:57.680 ","End":"02:01.175","Text":"The first thing is to output num1,"},{"Start":"02:01.175 ","End":"02:03.335","Text":"the content of num1,"},{"Start":"02:03.335 ","End":"02:06.890","Text":"so let\u0027s do that."},{"Start":"02:06.890 ","End":"02:13.145","Text":"Then to assign 2 temp the sum of num1 and num2 in part c2."},{"Start":"02:13.145 ","End":"02:14.750","Text":"We\u0027re assigning 2 temp."},{"Start":"02:14.750 ","End":"02:18.785","Text":"Temp comes on the left-hand side of the assignment operator,"},{"Start":"02:18.785 ","End":"02:23.215","Text":"the sum of num1 and num2. There we go."},{"Start":"02:23.215 ","End":"02:30.635","Text":"Then the next line we\u0027re required to assign 2 num1 the contents of num2."},{"Start":"02:30.635 ","End":"02:37.355","Text":"Num1 gets the contents of num2 on the right-hand side of the assignment operator."},{"Start":"02:37.355 ","End":"02:38.915","Text":"Then in Part 4,"},{"Start":"02:38.915 ","End":"02:41.870","Text":"assign to num2 the content of temp."},{"Start":"02:41.870 ","End":"02:45.200","Text":"So num2 gets the contents of temp,"},{"Start":"02:45.200 ","End":"02:46.910","Text":"which is on the right-hand side."},{"Start":"02:46.910 ","End":"02:49.655","Text":"Finally, we\u0027re asked to increment"},{"Start":"02:49.655 ","End":"02:53.045","Text":"the term variable so that we can involve any other variables."},{"Start":"02:53.045 ","End":"02:57.965","Text":"Just term plus plus is going to do it. That is it."},{"Start":"02:57.965 ","End":"03:03.145","Text":"Let\u0027s see what output is generated as part d asks us to do."},{"Start":"03:03.145 ","End":"03:06.850","Text":"Hopefully, it will match the numbers there."},{"Start":"03:06.850 ","End":"03:13.021","Text":"We are told the Fibonacci sequence does 0,"},{"Start":"03:13.021 ","End":"03:14.373","Text":"1, 1,"},{"Start":"03:14.373 ","End":"03:16.127","Text":"2, 3, 5,"},{"Start":"03:16.127 ","End":"03:18.005","Text":"8, 13, 21,"},{"Start":"03:18.005 ","End":"03:20.750","Text":"34, 55, 89, and 144."},{"Start":"03:20.750 ","End":"03:23.180","Text":"Let\u0027s have a look at what\u0027s actually going on here."},{"Start":"03:23.180 ","End":"03:27.020","Text":"We\u0027re terminating when term is less than or equal to limit."},{"Start":"03:27.020 ","End":"03:32.240","Text":"Presumably, we want a certain number of terms in the Fibonacci sequence,"},{"Start":"03:32.240 ","End":"03:33.710","Text":"12 is what we\u0027re looking for."},{"Start":"03:33.710 ","End":"03:38.390","Text":"We actually get 13 because we started with 0 being output."},{"Start":"03:38.390 ","End":"03:40.280","Text":"That\u0027s fine and that could be fixed if we wanted to,"},{"Start":"03:40.280 ","End":"03:41.810","Text":"but it\u0027s not too big a deal."},{"Start":"03:41.810 ","End":"03:44.160","Text":"We output the number."},{"Start":"03:44.160 ","End":"03:47.840","Text":"Then what we do is the way the Fibonacci sequence works is"},{"Start":"03:47.840 ","End":"03:51.950","Text":"each term in the sequence is the previous 2 add it together."},{"Start":"03:51.950 ","End":"03:57.185","Text":"That\u0027s why the first one being printed was 0 because that\u0027s what num1 was,"},{"Start":"03:57.185 ","End":"04:02.245","Text":"then we swapped num1 and num2 over num2 went into num1."},{"Start":"04:02.245 ","End":"04:04.790","Text":"But num2 got a new value,"},{"Start":"04:04.790 ","End":"04:08.615","Text":"which was the previous 2 added together and that\u0027s why we needed"},{"Start":"04:08.615 ","End":"04:13.370","Text":"temp pair because it was the value of num1 before we changed it in this line,"},{"Start":"04:13.370 ","End":"04:16.425","Text":"added to num2 before we change it in this line."},{"Start":"04:16.425 ","End":"04:17.865","Text":"We need a third variable,"},{"Start":"04:17.865 ","End":"04:19.680","Text":"temp in order to do that."},{"Start":"04:19.680 ","End":"04:21.620","Text":"It\u0027s a very common thing when you\u0027re swapping variables,"},{"Start":"04:21.620 ","End":"04:25.370","Text":"you\u0027ll need a third variable each time around the loop."},{"Start":"04:25.370 ","End":"04:27.485","Text":"Then we print the new value of num1,"},{"Start":"04:27.485 ","End":"04:29.990","Text":"which used to be the value of num2."},{"Start":"04:29.990 ","End":"04:35.360","Text":"Then it prints out all of the numbers in the sequence that we\u0027re expecting."},{"Start":"04:35.360 ","End":"04:37.435","Text":"If I wanted to print more numbers,"},{"Start":"04:37.435 ","End":"04:41.360","Text":"just change limit to 20 because I\u0027m limiting it to"},{"Start":"04:41.360 ","End":"04:45.620","Text":"the first 20 or 21 because I\u0027m counting zeros as well, terms."},{"Start":"04:45.620 ","End":"04:47.964","Text":"Let\u0027s just prove that that works."},{"Start":"04:47.964 ","End":"04:52.580","Text":"There you see we\u0027ve got the next items in the Fibonacci sequence."},{"Start":"04:52.580 ","End":"04:56.270","Text":"That\u0027s something a little bit more interesting than what we previously had."},{"Start":"04:56.270 ","End":"04:58.775","Text":"You could have actually done this with a for loop as well."},{"Start":"04:58.775 ","End":"05:02.300","Text":"But it\u0027s nice and elegant in the while loop,"},{"Start":"05:02.300 ","End":"05:07.610","Text":"they\u0027re relatively easy to follow once you understand how our Fibonacci sequence works."},{"Start":"05:07.610 ","End":"05:12.060","Text":"That\u0027s it for this one. I hope that\u0027s clear and I see you for the next one."}],"ID":28029},{"Watched":false,"Name":"Exercise 7","Duration":"9m 11s","ChapterTopicVideoID":26933,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:02.700","Text":"Welcome back to this next exercise,"},{"Start":"00:02.700 ","End":"00:07.590","Text":"which we have been asked to create a method for called while times tables."},{"Start":"00:07.590 ","End":"00:09.570","Text":"In that method, first of all,"},{"Start":"00:09.570 ","End":"00:14.230","Text":"we are asked to create an integer variable called table with an initial value of 2."},{"Start":"00:14.230 ","End":"00:17.025","Text":"Second integer variable called multiplier,"},{"Start":"00:17.025 ","End":"00:19.325","Text":"with an initial value of 1."},{"Start":"00:19.325 ","End":"00:23.475","Text":"In part b, we\u0027re asked to create a pair of nested while loops."},{"Start":"00:23.475 ","End":"00:25.350","Text":"The inner loop should iterate,"},{"Start":"00:25.350 ","End":"00:27.270","Text":"multiplier from 1 to 12,"},{"Start":"00:27.270 ","End":"00:31.215","Text":"and the outer loop should iterate table from 2 to 12."},{"Start":"00:31.215 ","End":"00:34.110","Text":"In Part c, we\u0027re asked at the appropriate point in"},{"Start":"00:34.110 ","End":"00:37.665","Text":"the code to output the contents of the multiplier variable,"},{"Start":"00:37.665 ","End":"00:40.075","Text":"followed by the String x,"},{"Start":"00:40.075 ","End":"00:42.515","Text":"followed by the contents of the table variable,"},{"Start":"00:42.515 ","End":"00:44.680","Text":"followed by the string equals."},{"Start":"00:44.680 ","End":"00:47.870","Text":"On the same line as the previous output in Part d,"},{"Start":"00:47.870 ","End":"00:52.340","Text":"we\u0027re asked to output the product of the multiplier and table variables."},{"Start":"00:52.340 ","End":"00:54.830","Text":"In Part e, we are asked to check that"},{"Start":"00:54.830 ","End":"00:59.540","Text":"the unlimited buffering option is ticked in the terminal window of BlueJ then test"},{"Start":"00:59.540 ","End":"01:03.320","Text":"the method by creating an object on the workbench and"},{"Start":"01:03.320 ","End":"01:07.475","Text":"checking that all 12 lines of each table are correctly output,"},{"Start":"01:07.475 ","End":"01:09.780","Text":"and to correct any errors found."},{"Start":"01:09.780 ","End":"01:12.980","Text":"In Part f, we\u0027re asked to add an integer variable called"},{"Start":"01:12.980 ","End":"01:15.980","Text":"line and to display its contents followed by"},{"Start":"01:15.980 ","End":"01:18.905","Text":"the literal string colon and a space before"},{"Start":"01:18.905 ","End":"01:22.295","Text":"each line of the times table is output to the screen."},{"Start":"01:22.295 ","End":"01:23.810","Text":"Finally, in Part g,"},{"Start":"01:23.810 ","End":"01:25.265","Text":"we\u0027re asked to test the method,"},{"Start":"01:25.265 ","End":"01:28.760","Text":"checking at all a 132 line numbers are"},{"Start":"01:28.760 ","End":"01:33.265","Text":"printed next to each line and to correct any errors found."},{"Start":"01:33.265 ","End":"01:38.405","Text":"Been asked to create a method called while times tables."},{"Start":"01:38.405 ","End":"01:45.634","Text":"It\u0027s going to do very much the same thing as we did previously with for-loop."},{"Start":"01:45.634 ","End":"01:49.790","Text":"Just to show us the difference between the 2 things and the fact"},{"Start":"01:49.790 ","End":"01:53.450","Text":"that really you can do pretty much anything you can do in a for-loop,"},{"Start":"01:53.450 ","End":"01:54.830","Text":"you can do with a while loop,"},{"Start":"01:54.830 ","End":"01:57.830","Text":"but it might be more elegant to do it in a for-loop."},{"Start":"01:57.830 ","End":"02:00.745","Text":"Let\u0027s carry on from 7a."},{"Start":"02:00.745 ","End":"02:05.195","Text":"We got to create an integer variable called table with initial value of 2 this time,"},{"Start":"02:05.195 ","End":"02:10.295","Text":"and a second integer variable called multiplier with an initial value of 1."},{"Start":"02:10.295 ","End":"02:12.155","Text":"Let\u0027s do that."},{"Start":"02:12.155 ","End":"02:20.930","Text":"Int table equals 2 and another integer called multiplier starts at 1."},{"Start":"02:20.930 ","End":"02:24.740","Text":"Then we\u0027re asked to create a pair of nested while loops."},{"Start":"02:24.740 ","End":"02:26.795","Text":"Let\u0027s create the first one."},{"Start":"02:26.795 ","End":"02:28.100","Text":"The inner loop should iterate,"},{"Start":"02:28.100 ","End":"02:29.540","Text":"multiplier from 1 to 12,"},{"Start":"02:29.540 ","End":"02:32.590","Text":"the outer loop should iterate table from 2 to 12."},{"Start":"02:32.590 ","End":"02:39.515","Text":"The outer loop is going to be table and we want to go up to an including 12."},{"Start":"02:39.515 ","End":"02:42.290","Text":"That is the outer loop,"},{"Start":"02:42.290 ","End":"02:49.260","Text":"and the inner loop needs to look like this because it\u0027s going to iterate multiplier."},{"Start":"02:51.430 ","End":"02:55.040","Text":"Part c asks us to,"},{"Start":"02:55.040 ","End":"02:56.870","Text":"at the appropriate point,"},{"Start":"02:56.870 ","End":"03:00.440","Text":"output the contents of the multiplier variable, followed by the String x,"},{"Start":"03:00.440 ","End":"03:02.225","Text":"followed by the contents of the table variable,"},{"Start":"03:02.225 ","End":"03:03.980","Text":"followed by the string equals."},{"Start":"03:03.980 ","End":"03:06.560","Text":"So where would be the appropriate point while the output"},{"Start":"03:06.560 ","End":"03:10.470","Text":"has to happen inside the inner loop?"},{"Start":"03:10.510 ","End":"03:13.940","Text":"This is the appropriate place to do it."},{"Start":"03:13.940 ","End":"03:20.615","Text":"We\u0027re going to put multiplier followed by x"},{"Start":"03:20.615 ","End":"03:28.099","Text":"followed by table and then a literal string with an equal sign in spaces."},{"Start":"03:28.099 ","End":"03:36.035","Text":"That\u0027s the first part and the second part should be print line here rather than print."},{"Start":"03:36.035 ","End":"03:40.805","Text":"We\u0027re going to multiply output."},{"Start":"03:40.805 ","End":"03:45.910","Text":"That\u0027s it. That should be what we need to before, or is it."},{"Start":"03:45.910 ","End":"03:47.990","Text":"Now with a for-loop,"},{"Start":"03:47.990 ","End":"03:49.370","Text":"we would have been done,"},{"Start":"03:49.370 ","End":"03:51.800","Text":"but with a while loop,"},{"Start":"03:51.800 ","End":"03:54.530","Text":"we are responsible for incrementing"},{"Start":"03:54.530 ","End":"03:58.670","Text":"the variables being used to terminate the loop if I was to run this now,"},{"Start":"03:58.670 ","End":"04:01.240","Text":"this would never end because"},{"Start":"04:01.240 ","End":"04:06.560","Text":"table is always going to be less than 12 because it always has 2,"},{"Start":"04:06.560 ","End":"04:07.985","Text":"and it never changes."},{"Start":"04:07.985 ","End":"04:09.910","Text":"Multiply would always be 1."},{"Start":"04:09.910 ","End":"04:12.905","Text":"This would just sit here forever printing the same old line."},{"Start":"04:12.905 ","End":"04:14.285","Text":"If you want me to prove it,"},{"Start":"04:14.285 ","End":"04:19.220","Text":"we can do I forgot to put void in front of this keyword here, so that\u0027s compliant."},{"Start":"04:19.220 ","End":"04:21.690","Text":"Le\u0027s try again. There we go."},{"Start":"04:21.700 ","End":"04:25.390","Text":"Let\u0027s try and run this method and see what happens,"},{"Start":"04:25.390 ","End":"04:29.035","Text":"and it would be, as I just predicted,"},{"Start":"04:29.035 ","End":"04:30.810","Text":"while times table,"},{"Start":"04:30.810 ","End":"04:34.880","Text":"and it just constantly prints out the same output again and again and again and"},{"Start":"04:34.880 ","End":"04:39.275","Text":"the only way I can stop it is to reset the virtual machine by clicking on that."},{"Start":"04:39.275 ","End":"04:40.910","Text":"Because that would run forever."},{"Start":"04:40.910 ","End":"04:42.500","Text":"You can see the output,"},{"Start":"04:42.500 ","End":"04:44.930","Text":"it\u0027s just repeating the same thing again and again"},{"Start":"04:44.930 ","End":"04:48.290","Text":"because I don\u0027t have a termination clause well I do,"},{"Start":"04:48.290 ","End":"04:52.025","Text":"but it\u0027s never going to satisfy this termination clause or this one"},{"Start":"04:52.025 ","End":"04:56.720","Text":"because I haven\u0027t ever changed the value of the multiplier and table variables."},{"Start":"04:56.720 ","End":"04:58.280","Text":"I\u0027m responsible for doing those,"},{"Start":"04:58.280 ","End":"05:01.700","Text":"so each time around this loop,"},{"Start":"05:01.700 ","End":"05:05.585","Text":"I need to increment multiplier,"},{"Start":"05:05.585 ","End":"05:08.795","Text":"and each time round this loop,"},{"Start":"05:08.795 ","End":"05:11.990","Text":"I need to increment table."},{"Start":"05:11.990 ","End":"05:16.225","Text":"That should then do what I need."},{"Start":"05:16.225 ","End":"05:18.330","Text":"Let\u0027s test that then,"},{"Start":"05:18.330 ","End":"05:23.020","Text":"and now it\u0027s worked for 1 table. Interesting. Why has it only worked for 1 table?"},{"Start":"05:23.570 ","End":"05:26.330","Text":"It\u0027s done the 2 times tables,"},{"Start":"05:26.330 ","End":"05:28.040","Text":"which is where I would have started."},{"Start":"05:28.040 ","End":"05:34.310","Text":"Is there something that is wrong here or what was happening here is it will"},{"Start":"05:34.310 ","End":"05:41.310","Text":"finish the first part and table is being incremented to the next table,"},{"Start":"05:41.310 ","End":"05:45.530","Text":"but it will never get to this again because I need to reset"},{"Start":"05:45.530 ","End":"05:53.020","Text":"multiplier to 0 or it will run this first line,"},{"Start":"05:53.020 ","End":"05:55.820","Text":"but it will find that multipliers already"},{"Start":"05:55.820 ","End":"05:59.445","Text":"more than 12 and therefore it\u0027s not going to do any of this."},{"Start":"05:59.445 ","End":"06:02.210","Text":"Low it was coming to this line each time we never saw"},{"Start":"06:02.210 ","End":"06:05.225","Text":"any output because it never got inside the loop."},{"Start":"06:05.225 ","End":"06:08.285","Text":"If I set multiplier to 0,"},{"Start":"06:08.285 ","End":"06:11.570","Text":"it should now do what I need it to do."},{"Start":"06:11.570 ","End":"06:13.670","Text":"Well and spelled it correctly,"},{"Start":"06:13.670 ","End":"06:16.295","Text":"so that will complain and that\u0027s better."},{"Start":"06:16.295 ","End":"06:19.280","Text":"Now let\u0027s see what happens. There we go."},{"Start":"06:19.280 ","End":"06:24.095","Text":"It seems to have corrected the error we had initially."},{"Start":"06:24.095 ","End":"06:26.615","Text":"There\u0027s all of our tables."},{"Start":"06:26.615 ","End":"06:31.910","Text":"The final bit we needed to do was to add an integer variable called line and"},{"Start":"06:31.910 ","End":"06:34.325","Text":"display its contents followed by"},{"Start":"06:34.325 ","End":"06:38.225","Text":"literal string before each line of the times tables output to the screen."},{"Start":"06:38.225 ","End":"06:40.505","Text":"Let\u0027s have a look at that."},{"Start":"06:40.505 ","End":"06:45.555","Text":"We need an integer variable called line on a separate line."},{"Start":"06:45.555 ","End":"06:50.975","Text":"I\u0027m going to start it at 1 because the first line is Line 1."},{"Start":"06:50.975 ","End":"06:53.450","Text":"Where should I output that?"},{"Start":"06:53.450 ","End":"06:56.180","Text":"Before I have any other output,"},{"Start":"06:56.180 ","End":"07:00.320","Text":"I want to output the number of the line."},{"Start":"07:00.320 ","End":"07:05.150","Text":"Here would seem to be an appropriate price system."},{"Start":"07:05.150 ","End":"07:09.035","Text":"I want it to be on the same line."},{"Start":"07:09.035 ","End":"07:15.345","Text":"I put line plus colon and a space."},{"Start":"07:15.345 ","End":"07:21.235","Text":"I also I\u0027m responsible for incrementing line."},{"Start":"07:21.235 ","End":"07:25.820","Text":"I\u0027ll do that each time I print 1 line, I need to increment."},{"Start":"07:25.820 ","End":"07:28.325","Text":"I can do it down here wouldn\u0027t make any difference,"},{"Start":"07:28.325 ","End":"07:31.145","Text":"but it doesn\u0027t need to be inside this inner loop."},{"Start":"07:31.145 ","End":"07:33.575","Text":"Let\u0027s see what happens."},{"Start":"07:33.575 ","End":"07:36.755","Text":"Now and it does do what I expect,"},{"Start":"07:36.755 ","End":"07:42.740","Text":"except for the fact that it\u0027s printing more lines than I would expect."},{"Start":"07:42.740 ","End":"07:45.985","Text":"That\u0027s because it\u0027s going to 0."},{"Start":"07:45.985 ","End":"07:49.040","Text":"It shouldn\u0027t be going to 0, it should be going to 1."},{"Start":"07:49.040 ","End":"07:52.175","Text":"When I set multiplier to 0,"},{"Start":"07:52.175 ","End":"07:55.865","Text":"I don\u0027t want to see that line 0 times something."},{"Start":"07:55.865 ","End":"07:58.285","Text":"That\u0027s the error had there."},{"Start":"07:58.285 ","End":"08:04.970","Text":"Even with a very small, better code is really easy to make multiple small errors."},{"Start":"08:04.970 ","End":"08:07.460","Text":"Now that should be a fix,"},{"Start":"08:07.460 ","End":"08:12.740","Text":"and I get a 132 lines, printed,"},{"Start":"08:12.740 ","End":"08:15.380","Text":"which is exactly what I expected,"},{"Start":"08:15.380 ","End":"08:19.145","Text":"but this time around there was scope for a few errors and I did have a few errors,"},{"Start":"08:19.145 ","End":"08:25.820","Text":"but I do have a 132 why 132 and 144 we didn\u0027t print the 1 times table, did we?"},{"Start":"08:25.820 ","End":"08:31.535","Text":"Because we started at 2 and we\u0027re 12 short of 144,"},{"Start":"08:31.535 ","End":"08:34.205","Text":"which is why it\u0027s a 132."},{"Start":"08:34.205 ","End":"08:35.780","Text":"Hope that made sense."},{"Start":"08:35.780 ","End":"08:38.615","Text":"We have done exactly what we had before."},{"Start":"08:38.615 ","End":"08:43.700","Text":"We\u0027ve got a couple of while loops nested inside each other."},{"Start":"08:43.700 ","End":"08:46.940","Text":"We are responsible for incrementing multiplier inside"},{"Start":"08:46.940 ","End":"08:50.450","Text":"this loop and table and the outer loop,"},{"Start":"08:50.450 ","End":"08:53.975","Text":"but we also have to set multiplier back to 1,"},{"Start":"08:53.975 ","End":"08:56.780","Text":"not 0 as I did but 1,"},{"Start":"08:56.780 ","End":"09:00.875","Text":"so that we see the first line of the table and next time around here."},{"Start":"09:00.875 ","End":"09:03.800","Text":"Otherwise, it will skip everything in here because it thinks"},{"Start":"09:03.800 ","End":"09:07.915","Text":"multiplier is already greater than or equal to 12."},{"Start":"09:07.915 ","End":"09:12.680","Text":"That\u0027s it. I\u0027ll see you in the next one."}],"ID":28030},{"Watched":false,"Name":"Exercise 8","Duration":"7m 2s","ChapterTopicVideoID":26934,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.450","Text":"Hi again, everyone. In this exercise we\u0027ve"},{"Start":"00:03.450 ","End":"00:06.544","Text":"been asked to create a new method called doWhileCount,"},{"Start":"00:06.544 ","End":"00:11.415","Text":"and in part A to use a doWhile loop to output the numbers from 1-10."},{"Start":"00:11.415 ","End":"00:14.190","Text":"In part B, we\u0027re asked to test the method and if it"},{"Start":"00:14.190 ","End":"00:17.850","Text":"continues producing output past 10 or appear to have crashed,"},{"Start":"00:17.850 ","End":"00:21.975","Text":"we can reset using the virtual machine icon in BlueJ."},{"Start":"00:21.975 ","End":"00:25.065","Text":"We are asked to then correct any errors found."},{"Start":"00:25.065 ","End":"00:27.270","Text":"In part c, in the same method,"},{"Start":"00:27.270 ","End":"00:30.285","Text":"we add another doWhile loop after the previous one,"},{"Start":"00:30.285 ","End":"00:34.995","Text":"which outputs the numbers from 10-100 in steps of 10."},{"Start":"00:34.995 ","End":"00:42.335","Text":"Once again, we test in part d and if it continues past 100 or appears to have crashed,"},{"Start":"00:42.335 ","End":"00:48.065","Text":"we click on the reset virtual machine icon in BlueJ and correct any errors found."},{"Start":"00:48.065 ","End":"00:50.930","Text":"In part e, we\u0027re asked in the same method"},{"Start":"00:50.930 ","End":"00:54.050","Text":"to add another doWhile loop after the previous one,"},{"Start":"00:54.050 ","End":"01:01.040","Text":"which outputs the numbers from 2,000 to minus 5,000 in steps of 100."},{"Start":"01:01.040 ","End":"01:02.420","Text":"Then in part F,"},{"Start":"01:02.420 ","End":"01:03.925","Text":"we test the method again,"},{"Start":"01:03.925 ","End":"01:07.655","Text":"if it goes past minus 5,000 or appears to crash,"},{"Start":"01:07.655 ","End":"01:09.920","Text":"we can reset using the BlueJ."},{"Start":"01:09.920 ","End":"01:12.095","Text":"But reset virtual machine icon,"},{"Start":"01:12.095 ","End":"01:15.085","Text":"and then we can correct any errors found."},{"Start":"01:15.085 ","End":"01:21.605","Text":"Now we\u0027re going to create some doWhile loop in the method called doWhileCount."},{"Start":"01:21.605 ","End":"01:24.770","Text":"Very similar to what we\u0027ve already done but using doWhile loops."},{"Start":"01:24.770 ","End":"01:26.840","Text":"Let\u0027s have a look at the difference in"},{"Start":"01:26.840 ","End":"01:31.805","Text":"syntax between this and a while loop and this a for loop."},{"Start":"01:31.805 ","End":"01:34.865","Text":"It starts with the keyword do,"},{"Start":"01:34.865 ","End":"01:37.820","Text":"and this time there are no brackets at all,"},{"Start":"01:37.820 ","End":"01:40.835","Text":"you close the brackets."},{"Start":"01:40.835 ","End":"01:44.378","Text":"At the end of the brackets you have the call or"},{"Start":"01:44.378 ","End":"01:48.829","Text":"the clause for the while and it didn\u0027t give me that hint there while expected."},{"Start":"01:48.829 ","End":"01:53.645","Text":"In this case, we\u0027ve been asked to output the numbers from 1-10."},{"Start":"01:53.645 ","End":"01:55.925","Text":"I want to keep going round while,"},{"Start":"01:55.925 ","End":"01:59.475","Text":"let\u0027s say i, is less than 10."},{"Start":"01:59.475 ","End":"02:02.180","Text":"It will still give me an error if I try and"},{"Start":"02:02.180 ","End":"02:05.270","Text":"compile that because this line needs terminating,"},{"Start":"02:05.270 ","End":"02:09.440","Text":"you\u0027ll see there\u0027s a red block there and it\u0027s telling me there\u0027s an error."},{"Start":"02:09.440 ","End":"02:14.840","Text":"It did say that semicolon expected so it\u0027s giving me a hint here in BlueJ currently,"},{"Start":"02:14.840 ","End":"02:18.740","Text":"but the syntax does require a semicolon."},{"Start":"02:18.740 ","End":"02:21.530","Text":"Didn\u0027t require that for a while loop or for a 4 loop and that\u0027s"},{"Start":"02:21.530 ","End":"02:26.330","Text":"because the closing bracket marks off the end of the block."},{"Start":"02:26.330 ","End":"02:29.623","Text":"Here, we\u0027ve got something following the block."},{"Start":"02:29.623 ","End":"02:32.315","Text":"It does need that line terminated."},{"Start":"02:32.315 ","End":"02:35.550","Text":"That would be what the syntax for the loop\u0027s going to look like,"},{"Start":"02:35.550 ","End":"02:38.750","Text":"but we didn\u0027t actually declare a variable i."},{"Start":"02:38.750 ","End":"02:40.215","Text":"We need to make sure we do that."},{"Start":"02:40.215 ","End":"02:44.835","Text":"It starting at 1 and it\u0027s going to go up to 10,"},{"Start":"02:44.835 ","End":"02:50.420","Text":"and the inside of the loop is going to be just the same as before."},{"Start":"02:50.420 ","End":"02:55.450","Text":"We are simply going to print the value of our variable."},{"Start":"02:55.450 ","End":"02:58.910","Text":"That is part A done and let\u0027s have"},{"Start":"02:58.910 ","End":"03:02.435","Text":"a go at doing it and seeing if there\u0027s any errors, there will be an error."},{"Start":"03:02.435 ","End":"03:03.740","Text":"What have I forgotten?"},{"Start":"03:03.740 ","End":"03:06.440","Text":"I forgotten to iterate the variables,"},{"Start":"03:06.440 ","End":"03:08.810","Text":"so I would have got a infinite loop again,"},{"Start":"03:08.810 ","End":"03:10.805","Text":"it would have just printed 1 forever"},{"Start":"03:10.805 ","End":"03:14.990","Text":"because i would never be greater than or equal to 10."},{"Start":"03:14.990 ","End":"03:19.558","Text":"Let\u0027s not make that error and let\u0027s just run it."},{"Start":"03:19.558 ","End":"03:23.645","Text":"I would expect the numbers 1-10 to be output and they are."},{"Start":"03:23.645 ","End":"03:28.895","Text":"Let\u0027s move on to part c. It\u0027s is same as before."},{"Start":"03:28.895 ","End":"03:36.165","Text":"This time we\u0027re going to terminate the loop when i reaches 100,"},{"Start":"03:36.165 ","End":"03:39.050","Text":"so i needs to be less than or equal to 100."},{"Start":"03:39.050 ","End":"03:40.775","Text":"In order for this loop to keep going,"},{"Start":"03:40.775 ","End":"03:43.235","Text":"don\u0027t forget the semicolon."},{"Start":"03:43.235 ","End":"03:46.820","Text":"We\u0027re going to increment i by 10 each"},{"Start":"03:46.820 ","End":"03:51.650","Text":"time around a loop and obviously we still need to output it."},{"Start":"03:51.650 ","End":"03:59.660","Text":"There we go, so system.out.printline and the increment is inside there."},{"Start":"03:59.660 ","End":"04:04.905","Text":"That will output from 10-100 in steps of 10."},{"Start":"04:04.905 ","End":"04:07.570","Text":"I should really set the value of i here,"},{"Start":"04:07.570 ","End":"04:13.090","Text":"but I know it\u0027s already going to be 10 when this loop finishes, or is it?"},{"Start":"04:13.090 ","End":"04:15.580","Text":"Let\u0027s try. Let\u0027s see what happens."},{"Start":"04:15.580 ","End":"04:19.270","Text":"What\u0027s happened is, is actually 11 and 21 and so on."},{"Start":"04:19.270 ","End":"04:21.955","Text":"Because at the end of the loop,"},{"Start":"04:21.955 ","End":"04:28.420","Text":"it had already incremented the value path 10-11."},{"Start":"04:28.420 ","End":"04:34.410","Text":"I do indeed need to set an i to 10 again,"},{"Start":"04:34.410 ","End":"04:38.980","Text":"because i would\u0027ve been incremented at this point and reached 11."},{"Start":"04:38.980 ","End":"04:41.440","Text":"The while clause then ran saying,"},{"Start":"04:41.440 ","End":"04:43.960","Text":"is it less than or equal to 10?"},{"Start":"04:43.960 ","End":"04:45.610","Text":"Now it\u0027s not, it\u0027s 11."},{"Start":"04:45.610 ","End":"04:47.635","Text":"Then it would exit out of the loop."},{"Start":"04:47.635 ","End":"04:50.142","Text":"If I had carried on printing, it will be 11, 21,"},{"Start":"04:50.142 ","End":"04:52.230","Text":"31 and so on,"},{"Start":"04:52.230 ","End":"04:54.700","Text":"so I do need to reset i to 10 there."},{"Start":"04:54.700 ","End":"04:58.280","Text":"Now, trust me, when I say that that will work and we\u0027ll test it next time around."},{"Start":"04:58.280 ","End":"05:01.790","Text":"In the final part, part E and F,"},{"Start":"05:01.790 ","End":"05:11.125","Text":"we are going to use the doWhile loop to output the numbers from 2,000 to minus 5,000."},{"Start":"05:11.125 ","End":"05:14.240","Text":"This is a slight variation on the earlier one,"},{"Start":"05:14.240 ","End":"05:17.520","Text":"where we would start to get 2,020,"},{"Start":"05:17.520 ","End":"05:22.970","Text":"and so the odd numbers came out at the end slightly [inaudible]."},{"Start":"05:22.970 ","End":"05:29.525","Text":"Let\u0027s have a look. This course that should be greater than or equal to minus 5,000."},{"Start":"05:29.525 ","End":"05:30.800","Text":"Whilst that is true,"},{"Start":"05:30.800 ","End":"05:33.059","Text":"we carry on printing."},{"Start":"05:33.140 ","End":"05:37.950","Text":"The value is in here."},{"Start":"05:37.950 ","End":"05:44.255","Text":"What we need to do with i is to subtract 100 each time around the loop."},{"Start":"05:44.255 ","End":"05:49.415","Text":"We do need an initial value of i of 2,000,"},{"Start":"05:49.415 ","End":"05:54.215","Text":"not 2,020 because it\u0027s easier to see the result with 2,000."},{"Start":"05:54.215 ","End":"05:59.162","Text":"That\u0027s it. Let\u0027s see what happens when we test it."},{"Start":"05:59.162 ","End":"06:08.070","Text":"Yes, it\u0027s hit minus 5,000 and it started at 2,000 here,"},{"Start":"06:08.070 ","End":"06:10.340","Text":"and we can still see the previous output as well,"},{"Start":"06:10.340 ","End":"06:14.180","Text":"the numbers 1-10 and then 10-100."},{"Start":"06:14.180 ","End":"06:17.405","Text":"We fix that problem that we had earlier wherever it\u0027s going from 11."},{"Start":"06:17.405 ","End":"06:22.130","Text":"The doWhile loop looks very similar to the while loop."},{"Start":"06:22.130 ","End":"06:25.640","Text":"We\u0027ve just got the termination clause at the bottom,"},{"Start":"06:25.640 ","End":"06:30.610","Text":"that does mean that the inside is always going to run at least once."},{"Start":"06:30.610 ","End":"06:33.515","Text":"If that\u0027s going to make a difference to your program,"},{"Start":"06:33.515 ","End":"06:36.260","Text":"didn\u0027t particularly in this one compared to the while loop 1,"},{"Start":"06:36.260 ","End":"06:37.805","Text":"they do exactly the same thing."},{"Start":"06:37.805 ","End":"06:42.620","Text":"But it could be possible for a doWhile loop to be more appropriate than"},{"Start":"06:42.620 ","End":"06:48.825","Text":"a while loop in situations where you want the inside always run at least once."},{"Start":"06:48.825 ","End":"06:52.445","Text":"If that\u0027s the case, then a doWhile loop it\u0027s going to be more appropriate."},{"Start":"06:52.445 ","End":"06:54.020","Text":"That\u0027s it for this one,"},{"Start":"06:54.020 ","End":"06:55.445","Text":"and in the final video,"},{"Start":"06:55.445 ","End":"07:00.500","Text":"we will see something slightly more useful using a doWhile loop,"},{"Start":"07:00.500 ","End":"07:03.180","Text":"so I\u0027ll see you shortly for that one."}],"ID":28031},{"Watched":false,"Name":"Exercise 9","Duration":"10m 22s","ChapterTopicVideoID":26935,"CourseChapterTopicPlaylistID":255413,"HasSubtitles":true,"ThumbnailPath":null,"UploadDate":null,"DurationForVideoObject":null,"Description":null,"MetaTitle":null,"MetaDescription":null,"Canonical":null,"VideoComments":[],"Subtitles":[{"Start":"00:00.000 ","End":"00:03.210","Text":"Hello again, everyone. In this exercise,"},{"Start":"00:03.210 ","End":"00:05.940","Text":"we\u0027re asked to create a new method called primeNumbers and in"},{"Start":"00:05.940 ","End":"00:08.910","Text":"Part a to declare and initialize a number of variables."},{"Start":"00:08.910 ","End":"00:12.490","Text":"Firstly, a variable called number with the value 2,"},{"Start":"00:12.490 ","End":"00:15.885","Text":"then a variable called factorsFound with the value 0,"},{"Start":"00:15.885 ","End":"00:18.720","Text":"limit with a value 20,"},{"Start":"00:18.720 ","End":"00:21.455","Text":"and a factor with no initial value."},{"Start":"00:21.455 ","End":"00:24.335","Text":"In Part b, we are asked to create a do while loop,"},{"Start":"00:24.335 ","End":"00:29.995","Text":"which terminates when number is no longer less than or equal to limit."},{"Start":"00:29.995 ","End":"00:31.470","Text":"In Part c,"},{"Start":"00:31.470 ","End":"00:33.770","Text":"within the do while loop that we created,"},{"Start":"00:33.770 ","End":"00:37.685","Text":"we\u0027re asked to first of all assign the value of number to factor,"},{"Start":"00:37.685 ","End":"00:40.880","Text":"then to create another do while loop which terminates"},{"Start":"00:40.880 ","End":"00:44.390","Text":"when factor is no longer greater than or equal to 2."},{"Start":"00:44.390 ","End":"00:46.265","Text":"Within the inner while loop,"},{"Start":"00:46.265 ","End":"00:50.510","Text":"we\u0027re asked to determine whether number divided by factor gives"},{"Start":"00:50.510 ","End":"00:56.120","Text":"a remainder of 0 and to increment the factorsFound variable when it does."},{"Start":"00:56.120 ","End":"00:58.815","Text":"Finally, within the inner do while loop"},{"Start":"00:58.815 ","End":"01:02.000","Text":"but after the conditional statement in Part iii above,"},{"Start":"01:02.000 ","End":"01:05.275","Text":"we\u0027re asked to decrement the factor variable."},{"Start":"01:05.275 ","End":"01:09.020","Text":"In Part d directly after the inner do while loop,"},{"Start":"01:09.020 ","End":"01:11.645","Text":"but inside the outer do while loop,"},{"Start":"01:11.645 ","End":"01:14.975","Text":"we\u0027re asked to check if factorsFound=1."},{"Start":"01:14.975 ","End":"01:18.800","Text":"If so, to output a message showing the current value of"},{"Start":"01:18.800 ","End":"01:23.310","Text":"the number variable followed by the literal string \"is a prime.\""},{"Start":"01:23.310 ","End":"01:27.320","Text":"In Part d ii, were asked to increment the number variable and in"},{"Start":"01:27.320 ","End":"01:31.715","Text":"d iii to assign a value 0 to factorsFound."},{"Start":"01:31.715 ","End":"01:34.460","Text":"Then we\u0027re asked to test the method produces"},{"Start":"01:34.460 ","End":"01:37.645","Text":"an output of all the prime numbers below 20,"},{"Start":"01:37.645 ","End":"01:41.750","Text":"these numbers here, and to correct any errors found."},{"Start":"01:41.750 ","End":"01:47.720","Text":"Finally, we\u0027re asked to change the initial value of limit to 100 and to test the method"},{"Start":"01:47.720 ","End":"01:54.405","Text":"again and that it produces output of all of the prime numbers below 100,"},{"Start":"01:54.405 ","End":"01:56.264","Text":"which would be these numbers,"},{"Start":"01:56.264 ","End":"01:59.665","Text":"and then to correct any errors found."},{"Start":"01:59.665 ","End":"02:06.440","Text":"Let\u0027s go and create a method called primeNumbers."},{"Start":"02:06.440 ","End":"02:10.930","Text":"Then we\u0027ve got to create some variables as usual in Part a."},{"Start":"02:10.930 ","End":"02:13.460","Text":"They look like they\u0027re all integers,"},{"Start":"02:13.460 ","End":"02:15.560","Text":"and so we can do that in one line."},{"Start":"02:15.560 ","End":"02:22.790","Text":"Number=2, factorsFound=0,"},{"Start":"02:22.790 ","End":"02:29.765","Text":"limit=20, and factor has no initial value."},{"Start":"02:29.765 ","End":"02:31.790","Text":"That\u0027s it for Part a."},{"Start":"02:31.790 ","End":"02:34.820","Text":"Then for Part b, we\u0027re asked to create a do while loop,"},{"Start":"02:34.820 ","End":"02:39.935","Text":"which terminates when number is no longer less than or equal to limit."},{"Start":"02:39.935 ","End":"02:45.260","Text":"Let\u0027s just think about the logic of the block."},{"Start":"02:45.260 ","End":"02:52.220","Text":"What needs to go in here terminates when number is no longer less than or equal to limit."},{"Start":"02:52.220 ","End":"02:59.255","Text":"Number needs to be greater than or equal to limit."},{"Start":"02:59.255 ","End":"03:05.945","Text":"As soon as it\u0027s no longer greater than or equal to limit, it will terminate."},{"Start":"03:05.945 ","End":"03:08.255","Text":"That\u0027s the Part b done."},{"Start":"03:08.255 ","End":"03:11.600","Text":"Then within this do while loop,"},{"Start":"03:11.600 ","End":"03:13.385","Text":"Part c i,"},{"Start":"03:13.385 ","End":"03:18.970","Text":"we\u0027re asked to assign the value of number to factor."},{"Start":"03:22.490 ","End":"03:28.250","Text":"Number goes into factor because we are assigning the value of number to factor."},{"Start":"03:28.250 ","End":"03:30.485","Text":"Then in Part c ii,"},{"Start":"03:30.485 ","End":"03:33.720","Text":"we were asked to create another do while loop,"},{"Start":"03:33.720 ","End":"03:35.970","Text":"so that\u0027s nested do while loop."},{"Start":"03:35.970 ","End":"03:41.360","Text":"Let\u0027s do that before we think about the termination clauses to do the blocks there."},{"Start":"03:41.360 ","End":"03:45.935","Text":"Let\u0027s then put while and it\u0027s saying"},{"Start":"03:45.935 ","End":"03:50.570","Text":"terminate when factor is no longer greater than or equal to 2."},{"Start":"03:50.570 ","End":"03:55.775","Text":"I want factor to be greater than or equal to 2."},{"Start":"03:55.775 ","End":"03:58.430","Text":"When it\u0027s not, it will terminate."},{"Start":"03:58.430 ","End":"04:01.100","Text":"Inside the inner do loop,"},{"Start":"04:01.100 ","End":"04:05.405","Text":"we determine whether a number divided by factor gives"},{"Start":"04:05.405 ","End":"04:09.680","Text":"a remainder of 0 and increment the factorsFound variable when it does."},{"Start":"04:09.680 ","End":"04:12.710","Text":"That sounds like we need an if statement."},{"Start":"04:12.710 ","End":"04:20.270","Text":"If number modulo factor=0,"},{"Start":"04:20.270 ","End":"04:23.214","Text":"because that\u0027s what we\u0027re doing when we use the modulo operator,"},{"Start":"04:23.214 ","End":"04:30.110","Text":"we\u0027re dividing factor into number and then we\u0027re comparing the remainder to 0,"},{"Start":"04:30.110 ","End":"04:32.525","Text":"see if there is no remainder."},{"Start":"04:32.525 ","End":"04:36.890","Text":"If it does, we increment the factorsFound variable."},{"Start":"04:36.890 ","End":"04:41.420","Text":"I can do that on the same line as the if statement."},{"Start":"04:41.420 ","End":"04:44.375","Text":"I don\u0027t need curly brackets if it\u0027s just one statement,"},{"Start":"04:44.375 ","End":"04:49.775","Text":"I can just put it immediately after the condition and then terminate with a semicolon."},{"Start":"04:49.775 ","End":"04:53.180","Text":"Then within the inner do while loop but after"},{"Start":"04:53.180 ","End":"04:56.555","Text":"the conditional statement that we\u0027ve just done,"},{"Start":"04:56.555 ","End":"04:59.240","Text":"we decrement the factor variable."},{"Start":"04:59.240 ","End":"05:04.980","Text":"We say factor minus minus to decrement."},{"Start":"05:04.980 ","End":"05:07.965","Text":"That\u0027s Part iv done."},{"Start":"05:07.965 ","End":"05:09.790","Text":"Then in Part d,"},{"Start":"05:09.790 ","End":"05:14.615","Text":"it\u0027s saying directly after the inner do while loop."},{"Start":"05:14.615 ","End":"05:19.940","Text":"This is the inner do while loop but inside the outer do while loop."},{"Start":"05:19.940 ","End":"05:22.280","Text":"This is the line that\u0027s directly after it."},{"Start":"05:22.280 ","End":"05:25.345","Text":"Check if factorsFound is=1."},{"Start":"05:25.345 ","End":"05:28.190","Text":"If so, output a message showing the current value of"},{"Start":"05:28.190 ","End":"05:32.525","Text":"the number variable followed by the literal string \"is a prime.\""},{"Start":"05:32.525 ","End":"05:35.720","Text":"We\u0027re going to need another if statement here and this time we\u0027re"},{"Start":"05:35.720 ","End":"05:42.435","Text":"saying if factorsFound is=1."},{"Start":"05:42.435 ","End":"05:45.050","Text":"When it is, we\u0027ll do another one line"},{"Start":"05:45.050 ","End":"05:49.130","Text":"if statement here because there\u0027s no else or anything else."},{"Start":"05:49.130 ","End":"05:50.390","Text":"There\u0027s only single line,"},{"Start":"05:50.390 ","End":"05:53.510","Text":"we don\u0027t need to have curly brackets."},{"Start":"05:53.510 ","End":"05:59.060","Text":"System out print line and we want to say the current value of"},{"Start":"05:59.060 ","End":"06:02.090","Text":"the number variable and then follow it with"},{"Start":"06:02.090 ","End":"06:08.480","Text":"a literal string \"is a prime\" and that\u0027s done."},{"Start":"06:08.480 ","End":"06:12.950","Text":"Then after that, but still inside the inner do while loop,"},{"Start":"06:12.950 ","End":"06:20.495","Text":"we want to increment a number variable and then assign the value 0 to factorsFound."},{"Start":"06:20.495 ","End":"06:23.105","Text":"That\u0027s everything we\u0027ve been asked to do."},{"Start":"06:23.105 ","End":"06:24.350","Text":"You should be able to run this."},{"Start":"06:24.350 ","End":"06:26.690","Text":"Now we\u0027ve got a do while loop and then"},{"Start":"06:26.690 ","End":"06:29.700","Text":"another one embedded inside that outer do while loop."},{"Start":"06:29.700 ","End":"06:35.805","Text":"Then a number of lines before and after do in a do while loop."},{"Start":"06:35.805 ","End":"06:38.210","Text":"We\u0027ve also got some conditionals in various places"},{"Start":"06:38.210 ","End":"06:40.715","Text":"that are a lot more complex than what we\u0027ve seen before."},{"Start":"06:40.715 ","End":"06:47.965","Text":"Let\u0027s see if we get what\u0027s expected in Part e. So create our object."},{"Start":"06:47.965 ","End":"06:49.925","Text":"We now have quite a few methods,"},{"Start":"06:49.925 ","End":"06:51.890","Text":"so we need to find where our method is."},{"Start":"06:51.890 ","End":"06:53.930","Text":"There it is, void primeNumbers."},{"Start":"06:53.930 ","End":"06:58.160","Text":"Let\u0027s run that, we\u0027re expecting a series of numbers,"},{"Start":"06:58.160 ","End":"07:00.055","Text":"but I only get one."},{"Start":"07:00.055 ","End":"07:01.955","Text":"What have I done wrong?"},{"Start":"07:01.955 ","End":"07:05.330","Text":"We know there\u0027s more than one prime number below 20."},{"Start":"07:05.330 ","End":"07:09.005","Text":"I have done something wrong somewhere."},{"Start":"07:09.005 ","End":"07:12.140","Text":"What it is, is this line here."},{"Start":"07:12.140 ","End":"07:16.070","Text":"I\u0027ve said, well, number is greater than or equal to limit."},{"Start":"07:16.070 ","End":"07:19.340","Text":"That\u0027s going to work the first time round because"},{"Start":"07:19.340 ","End":"07:22.640","Text":"it will always run once, this thing here."},{"Start":"07:22.640 ","End":"07:28.865","Text":"But number is not going to be greater than or equal to limit at any point."},{"Start":"07:28.865 ","End":"07:32.840","Text":"It will run once, but it will never run again because number is only"},{"Start":"07:32.840 ","End":"07:37.220","Text":"2 when we start and it gets incremented by 1 each time around the loop."},{"Start":"07:37.220 ","End":"07:39.260","Text":"I\u0027ve got this the wrong way round."},{"Start":"07:39.260 ","End":"07:44.374","Text":"It should be while number is less than or equal to limit."},{"Start":"07:44.374 ","End":"07:48.230","Text":"That hopefully will fix my problem."},{"Start":"07:48.230 ","End":"07:50.250","Text":"Let\u0027s see if that\u0027s true."},{"Start":"07:50.250 ","End":"07:54.650","Text":"Sure enough, I get all of the prime numbers below 20; 2, 3,"},{"Start":"07:54.650 ","End":"07:56.450","Text":"5, 7, 11,"},{"Start":"07:56.450 ","End":"07:59.750","Text":"13, 17, and 19."},{"Start":"07:59.750 ","End":"08:02.840","Text":"I was asked then to change in Part f,"},{"Start":"08:02.840 ","End":"08:08.117","Text":"the initial value of limit to 100 because it was only 20 before,"},{"Start":"08:08.117 ","End":"08:14.045","Text":"just to see if my code still works for all of the prime numbers below 100."},{"Start":"08:14.045 ","End":"08:19.045","Text":"Let\u0027s see if that does indeed generate the output I\u0027m expecting."},{"Start":"08:19.045 ","End":"08:22.970","Text":"There we go, all the numbers that I had previously,"},{"Start":"08:22.970 ","End":"08:25.010","Text":"but then we\u0027re going beyond 20 now,"},{"Start":"08:25.010 ","End":"08:28.025","Text":"all the way up to but not including 100."},{"Start":"08:28.025 ","End":"08:30.590","Text":"These are all of the numbers below 100."},{"Start":"08:30.590 ","End":"08:32.300","Text":"100 is not a prime number itself,"},{"Start":"08:32.300 ","End":"08:33.605","Text":"so that\u0027s why we\u0027re not going to see 100,"},{"Start":"08:33.605 ","End":"08:36.080","Text":"but there will be a number just above it."},{"Start":"08:36.080 ","End":"08:38.750","Text":"That is it."},{"Start":"08:38.750 ","End":"08:41.900","Text":"Quite complex program really."},{"Start":"08:41.900 ","End":"08:45.824","Text":"What it was doing was this inner do"},{"Start":"08:45.824 ","End":"08:51.095","Text":"while loop here was trying to see how many factors we find."},{"Start":"08:51.095 ","End":"08:53.225","Text":"A prime number by definition,"},{"Start":"08:53.225 ","End":"08:57.050","Text":"is only a prime number if it only has one factor,"},{"Start":"08:57.050 ","End":"08:58.840","Text":"not including 1,"},{"Start":"08:58.840 ","End":"09:03.780","Text":"so is divisible by itself and 1."},{"Start":"09:03.780 ","End":"09:05.885","Text":"We weren\u0027t dividing by 1 anyway here,"},{"Start":"09:05.885 ","End":"09:08.705","Text":"so we were just looking to see if it had more than one factor."},{"Start":"09:08.705 ","End":"09:13.010","Text":"If it did, we know that it\u0027s not a prime number,"},{"Start":"09:13.010 ","End":"09:15.740","Text":"but if it did I only have exactly one factor,"},{"Start":"09:15.740 ","End":"09:19.475","Text":"then it was a prime number and we printed out this line here."},{"Start":"09:19.475 ","End":"09:23.060","Text":"It just carried on until it reached the limit,"},{"Start":"09:23.060 ","End":"09:25.690","Text":"in which case it just stop."},{"Start":"09:25.690 ","End":"09:31.925","Text":"We can make this as big as we like and it would generate a whole series of numbers."},{"Start":"09:31.925 ","End":"09:36.215","Text":"The beauty of programming really is you can do with very little effort,"},{"Start":"09:36.215 ","End":"09:38.060","Text":"a lot more work."},{"Start":"09:38.060 ","End":"09:39.895","Text":"Let\u0027s just see that and look at that,"},{"Start":"09:39.895 ","End":"09:41.810","Text":"all of the prime numbers up to 1,000."},{"Start":"09:41.810 ","End":"09:45.335","Text":"We could do 1,000,000 if we wanted to and it would happily do them,"},{"Start":"09:45.335 ","End":"09:48.560","Text":"but perhaps not in this exercise right now."},{"Start":"09:48.560 ","End":"09:52.325","Text":"That\u0027s it, so I hope that was straightforward."},{"Start":"09:52.325 ","End":"09:55.040","Text":"In the end, there was a lot of different steps."},{"Start":"09:55.040 ","End":"10:00.200","Text":"But the real main thing we\u0027re looking here for and my deliberate error at the beginning"},{"Start":"10:00.200 ","End":"10:05.645","Text":"there was just to show you that you\u0027d always run at least once a do while loop."},{"Start":"10:05.645 ","End":"10:07.700","Text":"That\u0027s why when I had an error before,"},{"Start":"10:07.700 ","End":"10:09.335","Text":"when I had this the wrong way around,"},{"Start":"10:09.335 ","End":"10:11.675","Text":"it did show at least 1 prime number,"},{"Start":"10:11.675 ","End":"10:14.105","Text":"but it didn\u0027t show all of them because"},{"Start":"10:14.105 ","End":"10:17.690","Text":"this was terminating the loop after it had done one."},{"Start":"10:17.690 ","End":"10:22.680","Text":"Thanks very much for watching and I\u0027ll see you soon."}],"ID":28032}],"Thumbnail":null,"ID":255413}]

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1.2

11