WEBVTT 00:00.730 --> 00:08.300 In this lecture we'll go over medic operations that you can do these will really be like grade school 00:08.300 --> 00:10.540 math that you've done. 00:11.090 --> 00:24.380 So what starch won't say we have a variable x and we'll sign it five in one of it y and will sign it 00:24.470 --> 00:36.900 11 Let's make another one say Zed and we'll say X plus Wise's the addition operator so we'll see what 00:36.900 --> 00:38.160 this output it's 00:41.010 --> 00:43.870 you said is 00:52.050 --> 00:55.570 No it's right. 00:55.720 --> 00:59.700 And it gives you 16 as you probably expect. 00:59.740 --> 01:07.270 So it's so shy a minus. 01:07.490 --> 01:13.520 He's negative 6 and multiply that should give you five. 01:13.520 --> 01:14.450 Right. 01:15.080 --> 01:23.040 So these are what are called a binary operator binary meaning there's two sides to this operators. 01:23.060 --> 01:28.550 You have the operator in the middle and then you have on the left side of this X and then on the right 01:28.550 --> 01:30.130 side the Y. 01:30.140 --> 01:33.990 That's why it's binary because it works on two different sides of itself. 01:35.640 --> 01:41.840 But let's see what happens if you say divide things get a bit more interesting. 01:43.050 --> 01:46.870 It's from that and the value is zero. 01:47.720 --> 01:57.710 Rants are saying 5 which is the value X and 11 which is the value y and 0. 01:57.840 --> 01:59.210 And why is that while. 01:59.250 --> 02:08.660 Like I said in The Last Lecture types are interpreted in a specific way and integers are whole numbers. 02:08.720 --> 02:19.820 So you can't have something like zero point five or something like this for like that it'll always lop 02:19.820 --> 02:24.710 off the end of it which should be its decimal point onwards. 02:24.740 --> 02:29.400 And just use the whole number which would be zero in this case. 02:29.450 --> 02:31.940 So you have to be very careful about that. 02:31.970 --> 02:38.030 In fact you can actually take advantage of it in certain situations which we'll probably see later on. 02:39.200 --> 02:45.710 So let's use a different operator called the modulus operator. 02:45.710 --> 02:47.550 This is the percent sign. 02:49.140 --> 02:56.820 So if you remember back in your grade for five or three math class you probably went over something 02:56.820 --> 03:04.390 like long division and if you remember if something didn't evenly divide you always get a remainder. 03:04.790 --> 03:07.360 And this is what this is. 03:07.370 --> 03:21.170 So if you had say 11 as X into Y What do you think the value would be. 03:21.230 --> 03:23.060 What is the Zenn value here. 03:24.530 --> 03:35.680 Well it's one because you will divide 11 five times but there will be one remainer rate and that's what 03:35.860 --> 03:40.840 that's what this one is the remainder of the division that was was done 03:44.580 --> 03:53.080 and modulus is very useful for certain things and be using it quite a bit more later on in our programs. 03:53.430 --> 04:00.480 Is also very nice shortcuts to some of the operations that we can do. 04:01.720 --> 04:15.850 So say you wanted to we had X equals one and we said it's said as. 04:15.890 --> 04:22.600 For now let's say we had wanted to say X equals x 04:25.540 --> 04:31.340 plus 1 plus one can. 04:31.390 --> 04:37.090 So we're saying X gets value x plus 1. 04:37.100 --> 04:40.390 So at the end of this this should be two right. 04:41.060 --> 04:45.160 And we should have four as our result for zed 04:51.580 --> 04:52.810 for here. 04:53.100 --> 05:05.790 Well there's this shorthand that you can do it x plus plus this will be the same same results as above. 05:07.170 --> 05:08.530 Let's just comment that out 05:11.410 --> 05:14.040 and you should see again values for. 05:14.050 --> 05:15.490 So what is this. 05:15.540 --> 05:23.460 This line here this line 20 x plus plus is the exact same as this line above. 05:23.470 --> 05:30.900 In fact it's just a nice shorthand for this is what's called incrementing something. 05:31.300 --> 05:34.810 And you can actually do the same with decrementing as well. 05:34.960 --> 05:44.890 So you can actually say X minus minus will be the equivalent of X equals X minus 1. 05:45.030 --> 05:50.110 See that she's just 2 so X would be 0 at this point. 05:51.020 --> 05:57.090 At the end of 20 line 20 and 0 plus due to 06:00.770 --> 06:08.180 there's also other shorthands that are kind of interesting which are these show you do you do something 06:08.180 --> 06:09.160 like this as well. 06:09.180 --> 06:12.190 X plus equals 1. 06:12.260 --> 06:16.680 This will be the same as X plus plus with the same 06:21.470 --> 06:22.540 same ones. 06:22.750 --> 06:30.480 You also have X minus equals 1 which would be the same as X minus minus even use multiplying. 06:30.500 --> 06:37.190 So X times equals 2 which would multiply it by 2 and reassign the value. 06:37.430 --> 06:42.330 And you can do even to divide and modulus as well. 06:42.370 --> 06:49.220 So that's something interesting to keep in mind just for these are just shorthands programmers very 06:49.220 --> 06:54.700 much like shorthands because we don't want to type code all the time. 06:56.210 --> 07:01.980 So these are the basic operations that will work for. 07:02.140 --> 07:05.340 Double float and so on. 07:07.480 --> 07:11.200 But for char's This also works. 07:11.200 --> 07:14.260 So let's say we had to delete all this 07:17.030 --> 07:30.920 and say we can't share C equals a and we said C plus plus K. 07:31.130 --> 07:36.310 What do you think the value of c is. 07:36.330 --> 07:40.650 If we run it it's B. 07:40.950 --> 07:47.880 Capital B so you can actually add 1 to. 07:48.020 --> 07:51.950 This is actually this is a single coded a. 07:51.980 --> 08:01.730 Here is actually a number and that number corresponds with the what's called an ASCII table. 08:01.730 --> 08:13.220 So the ASCII table will have all of the letters and numbers for the ASCII set character set and this 08:13.220 --> 08:16.350 corresponds to a specific number. 08:16.490 --> 08:20.360 So A is 70 something I can't remember really. 08:20.480 --> 08:27.560 So one thing you should do after this lecture you shouldn't look up all the Ask the ASCII table and 08:27.920 --> 08:31.330 check to see what value a has. 08:31.330 --> 08:41.520 So in this case you should print out since we're adding 1 to a and then incrementing it at c or so. 08:41.870 --> 08:49.780 Remember Like I said it's all interpreted differently even though it could be used similarly. 08:49.780 --> 08:54.480 So we're using the binary operator addition here. 08:55.020 --> 09:03.630 And this is what's called a unitary operator because it only acts on one side as plussed class a unique 09:03.720 --> 09:06.890 OPERATOR So one unit. 09:07.050 --> 09:09.590 You mean in French 09:16.480 --> 09:24.870 so the last thing I want to talk about with arithmetic operations is what's called precedence. 09:25.270 --> 09:32.500 So let's say we had our original example here 09:36.030 --> 09:40.830 sequels five why sloven 09:43.100 --> 09:50.130 in said Kuhn's X plus Y. 09:50.530 --> 09:55.340 So this. 09:56.520 --> 10:01.180 So you'll notice here what happens first. 10:02.380 --> 10:10.810 Because you have two different Opper operators we have the addition operator and we have the assignment 10:10.840 --> 10:13.060 operator as well. 10:13.060 --> 10:17.480 And yet we know the results is 16. 10:17.500 --> 10:29.970 So we know it does this X plus wife first and then it assigns it that value 16 to Zed Well like I said 10:29.970 --> 10:40.320 this is called precedence and this this is something that all operators have in precedence is really 10:41.220 --> 10:47.340 you can think of it as kind of the order of operations that will happen first. 10:47.570 --> 10:56.030 So in this case this addition has higher precedence than the assignment because that's what was completed 10:56.030 --> 10:56.900 first. 10:58.390 --> 11:00.900 Here's another example. 11:00.970 --> 11:16.600 So let's say we had Zed equals 10 watts 30 times every 6 or 6 minus 9 11:20.970 --> 11:22.980 and this 11:27.220 --> 11:29.610 sace what's the end result. 11:29.620 --> 11:32.260 It's 181 k. 11:32.330 --> 11:37.250 So what happens first well if you remember you're old. 11:37.390 --> 11:46.030 Matthew probably learned something something effective bed mass which is multiplication and division 11:46.600 --> 11:51.010 will come before subtraction and addition. 11:51.070 --> 12:02.630 So this happens first this 36 times or 30 times 36 and then it gets divided and then you add then subtract. 12:02.630 --> 12:03.110 Right. 12:05.120 --> 12:11.660 So if you look up the there's also besides the ASCII table is also something called precedence table 12:12.740 --> 12:20.800 and you'll see in the precedence table that multiply and divide are at the same level but multiply will 12:20.800 --> 12:27.790 come first and it's higher precedence than addition or subtraction. 12:27.790 --> 12:34.480 Now if you don't remember any of this stuff which I I rarely don't want to remember what you should 12:34.480 --> 12:41.600 do is have parentheses around every so if you wanted this to happen first 12:46.720 --> 12:49.890 you'll still see 181 as the result. 12:50.050 --> 12:56.590 If say you wanted a different precedence Let's say you want to do the dition first 13:00.260 --> 13:05.210 10 plus 30 times 36 minus 9 13:10.110 --> 13:13.410 that give you a totally different number 8. 13:13.420 --> 13:23.810 So if you if you don't want any kind of ambiguity you really want to use your make clear use of parentheses 13:23.840 --> 13:25.950 to say what should come first. 13:25.970 --> 13:27.320 This will always happen first. 13:27.320 --> 13:36.810 This 10 plus 30 then it will multiply by 36 and divide and will subtract. 13:36.810 --> 13:45.850 So this is very very important stuff so always just remember if you don't want any ambiguity use use 13:45.880 --> 13:47.180 these parentheses. 13:47.350 --> 13:53.150 And after the lecture you should go and look up the both the ASCII table and the precedence table. 13:53.160 --> 13:58.140 See all of the operations that come for what. 13:58.200 --> 14:02.610 So in the next lecture we'll start talking about some simple input.