WEBVTT 0 00:00.590 --> 00:08.270 Very often I've asked you in the quizzes especially to play computer, and the reason is because this 1 00:08.270 --> 00:13.580 skill of pretending to be a computer, reading through your code and imagining what you're going to 2 00:13.580 --> 00:18.830 do each time is really, really useful, especially when you're debugging. 3 00:18.860 --> 00:20.600 Take a look at this code. 4 00:20.810 --> 00:28.730 It takes an input in the form of an integer, and it asks the user for their year of birth, and then 5 00:28.730 --> 00:37.040 it uses an if statement to check if they were born between 1980 and 1994, in which case they're classified 6 00:37.040 --> 00:38.120 as a Millennial. 7 00:38.840 --> 00:44.300 But if they were born later than 1994, then they're classified as a Gen Z. 8 00:44.480 --> 00:50.720 So depending on which country you're from, there's different classifications for your particular generation. 9 00:50.720 --> 00:54.350 This is just the typical words that you hear on the internet, 10 00:54.350 --> 00:57.380 "You're a Millennial, you're a Gen Z, you're a Baby boomer." 11 00:57.380 --> 01:00.050 And this comes from a lot of the history of the US. 12 01:00.860 --> 01:08.720 But nonetheless, I want you to run the code, and I want you to see what happens when I put in 1994 13 01:08.870 --> 01:10.850 absolutely nothing. 14 01:10.850 --> 01:12.800 So we have our bug right there. 15 01:12.920 --> 01:19.610 Run through the code line by line and evaluate each statement and follow the logic and check what it 16 01:19.610 --> 01:20.960 will evaluate to. 17 01:20.990 --> 01:25.640 So I want you to play computer and figure out what is the problem, 18 01:25.640 --> 01:28.340 and then go ahead and fix the bug. 19 01:28.670 --> 01:29.810 Pause the video now. 20 01:32.720 --> 01:33.230 All right. 21 01:33.230 --> 01:37.670 So let's pretend that we got 1994 as the input. 22 01:37.670 --> 01:39.680 So now I'm the computer 23 01:39.680 --> 01:43.820 and I know that this year is equal to 1994. 24 01:43.850 --> 01:49.130 Now with this year being equal to 1994, I go into this if statement. 25 01:49.130 --> 01:53.720 So is 1994 greater than 1980? 26 01:54.380 --> 01:55.730 Yes it is. 27 01:55.730 --> 01:58.670 So this actually becomes True. 28 01:59.120 --> 02:01.760 Now I have to check the second condition, 29 02:01.760 --> 02:04.220 and it also has to be True for this 30 02:04.250 --> 02:05.930 if block to be triggered. 31 02:05.930 --> 02:10.370 So is 1994 less than 1994? 32 02:10.370 --> 02:11.240 No it's not. 33 02:11.240 --> 02:17.790 It's actually less than equal to 1994 or it's equal to 1994. 34 02:17.910 --> 02:21.630 So in this case, this condition becomes False, 35 02:21.630 --> 02:28.650 and we know that if we try to combine a True and a False, then it actually just becomes a False. 36 02:28.650 --> 02:30.510 So this gets skipped. 37 02:31.080 --> 02:34.590 Now next we look at the next statement, right? 38 02:34.590 --> 02:41.240 If 1994 is greater than 1994 well that's also not True. 39 02:41.270 --> 02:43.160 It could be greater or equal to, 40 02:43.160 --> 02:45.230 or it could just be equal to. 41 02:45.260 --> 02:48.860 So this condition is also False. 42 02:48.860 --> 02:52.190 So that means it's also going to skip this next line 43 02:52.190 --> 02:57.320 and there's no more lines of code left, which is why the computer doesn't print anything. 44 02:57.320 --> 03:02.060 So let's restore our code to before we started playing computer. 45 03:02.060 --> 03:12.170 And we can identify that this problem occurs because there is no bucket that actually catches the 1994. 46 03:12.320 --> 03:20.120 We could simply fix this code by changing one of these conditions to be greater than, or equal to, either 47 03:20.120 --> 03:21.590 here or here. 48 03:21.770 --> 03:27.080 And that means that the year 1994 is not skipped over in our conditions. 49 03:27.080 --> 03:32.390 And when we hit Run, it'll actually tell us that we are, in fact, a Gen Z.