1 00:00:00,740 --> 00:00:02,270 Hi there and welcome back. 2 00:00:02,270 --> 00:00:03,330 In this coding exercise, 3 00:00:03,330 --> 00:00:06,330 we looked at loops and if statements 4 00:00:06,330 --> 00:00:08,710 and we've got two parts to the coding exercise. 5 00:00:08,710 --> 00:00:10,680 In one of them, we have to use an if statement 6 00:00:10,680 --> 00:00:12,540 inside a loop and in the other one, 7 00:00:12,540 --> 00:00:16,200 we have to use the if statement's elif clause. 8 00:00:16,200 --> 00:00:18,650 But let's take a look at how we could solve this. 9 00:00:19,870 --> 00:00:20,703 First things first, 10 00:00:20,703 --> 00:00:23,970 you have to read the coding exercise description, of course 11 00:00:24,890 --> 00:00:28,440 and here we've got, now the coding exercise has two steps. 12 00:00:28,440 --> 00:00:30,490 You have to modify the code in the first step 13 00:00:30,490 --> 00:00:33,710 so that the evens list contains only the even numbers 14 00:00:33,710 --> 00:00:34,890 of the numbers list. 15 00:00:34,890 --> 00:00:36,940 So we have the numbers list down here. 16 00:00:36,940 --> 00:00:39,160 It has numbers from one to nine 17 00:00:39,160 --> 00:00:42,150 and then we have an evens list that is empty 18 00:00:42,150 --> 00:00:45,750 and here we have a for loop for number in numbers 19 00:00:45,750 --> 00:00:48,920 and every number we're going to append, 20 00:00:48,920 --> 00:00:50,840 so clearly the evens list at the moment 21 00:00:50,840 --> 00:00:52,930 is going to end up with all the same numbers 22 00:00:52,930 --> 00:00:54,530 as the numbers list. 23 00:00:54,530 --> 00:00:55,430 So we want to make sure 24 00:00:55,430 --> 00:00:58,520 that only the even numbers get appended. 25 00:00:58,520 --> 00:01:00,610 And the description here says 26 00:01:00,610 --> 00:01:03,120 that you do not need to print anything. 27 00:01:03,120 --> 00:01:05,930 So we will just append things there and that's it. 28 00:01:05,930 --> 00:01:07,690 For part two, we need to add a clause 29 00:01:07,690 --> 00:01:09,890 to the if statement such that is the user's input 30 00:01:09,890 --> 00:01:11,520 is q in lowercase, 31 00:01:11,520 --> 00:01:14,820 then our programme prints Quit with the uppercase Q. 32 00:01:14,820 --> 00:01:16,840 And remember, that Python will care about uppercase 33 00:01:16,840 --> 00:01:18,990 and lowercase letters, so that's important. 34 00:01:20,640 --> 00:01:23,030 Let's bring this back up here 35 00:01:23,030 --> 00:01:24,720 and here we have the if statement. 36 00:01:24,720 --> 00:01:26,630 If the user's input is a in lowercase, 37 00:01:26,630 --> 00:01:27,520 we're printing Add, 38 00:01:27,520 --> 00:01:30,380 so we have to add another if clause there 39 00:01:30,380 --> 00:01:33,420 to make sure that if it's q, we print Quit. 40 00:01:33,420 --> 00:01:35,780 Let's tackle part one first. 41 00:01:35,780 --> 00:01:37,170 Here we're appending every number 42 00:01:37,170 --> 00:01:39,430 in the numbers list to the evens list 43 00:01:39,430 --> 00:01:40,540 so what we have to do is make sure 44 00:01:40,540 --> 00:01:42,130 that we only append some numbers, 45 00:01:42,130 --> 00:01:43,640 the numbers that are even. 46 00:01:43,640 --> 00:01:45,970 In order to check for even numbers in Python, 47 00:01:45,970 --> 00:01:48,110 we can use the modulus operator. 48 00:01:48,110 --> 00:01:51,975 We can say if number is divisible by two, 49 00:01:51,975 --> 00:01:52,820 so what the modulus operator does 50 00:01:52,820 --> 00:01:54,630 is it gives us the remainder 51 00:01:54,630 --> 00:01:57,690 of a division, so if the number divided by two 52 00:01:57,690 --> 00:02:00,860 has no remainder, then this will be zero 53 00:02:00,860 --> 00:02:03,190 and that is how we can tell whether a number is divisible 54 00:02:03,190 --> 00:02:05,140 by another number. 55 00:02:05,140 --> 00:02:06,550 So here we'll check whether number 56 00:02:06,550 --> 00:02:08,100 is divisible by two 57 00:02:08,100 --> 00:02:11,210 and if it is, then we will append the events list. 58 00:02:11,210 --> 00:02:12,740 If it's not, then we won't. 59 00:02:12,740 --> 00:02:14,940 Going to part two, all we have to do here 60 00:02:14,940 --> 00:02:16,693 is add an elif clause. 61 00:02:17,571 --> 00:02:21,630 So we can say elif user_input is equal to q, 62 00:02:21,630 --> 00:02:22,683 then we will print. 63 00:02:24,500 --> 00:02:27,120 You could just do an if statement, a separate one 64 00:02:27,120 --> 00:02:29,550 but that will be a little bit slower in Python terms, 65 00:02:29,550 --> 00:02:31,600 so if you can use the elif here, 66 00:02:31,600 --> 00:02:32,570 then that's better. 67 00:02:32,570 --> 00:02:34,270 You can use the elif because the user input 68 00:02:34,270 --> 00:02:37,320 will never be both a and q at the same time, 69 00:02:37,320 --> 00:02:39,900 so there's no sense in checking both of them. 70 00:02:39,900 --> 00:02:41,040 If the user's input is a, 71 00:02:41,040 --> 00:02:43,550 then we're not going to check whether it's q. 72 00:02:43,550 --> 00:02:45,880 So that will give us a little bit of a speed boost, 73 00:02:45,880 --> 00:02:47,850 a very small one granted. 74 00:02:47,850 --> 00:02:48,683 Once you've got that, 75 00:02:48,683 --> 00:02:50,200 you can check the solution 76 00:02:50,200 --> 00:02:51,550 and make sure it's correct. 77 00:02:53,110 --> 00:02:54,530 And here we can see that it is correct, 78 00:02:54,530 --> 00:02:56,903 so we can continue when we're happy with that. 79 00:02:57,920 --> 00:02:59,300 As always, if you have any questions, 80 00:02:59,300 --> 00:03:01,250 do post them in the course Q and A 81 00:03:01,250 --> 00:03:04,000 and we'll be more than happy to help you out. 82 00:03:04,000 --> 00:03:05,690 Thanks for joining me in this video. 83 00:03:05,690 --> 00:03:08,440 Hope it's been useful and I'll see you in the next one.