1 00:00:04,460 --> 00:00:09,510 So the challenge that I mentioned in the last video was to modify the program, our 2 00:00:09,510 --> 00:00:13,720 guessing game, using a while loop to allow the player to continue guessing. 3 00:00:13,720 --> 00:00:18,240 The important change is the use of a while loop. As long as the guess doesn't 4 00:00:18,240 --> 00:00:22,470 equal the answer, the loop will continue requesting a new guess and checking 5 00:00:22,470 --> 00:00:26,310 the answer. So I'm going to start by wrapping all the code, including the 6 00:00:26,310 --> 00:00:31,380 input line, in a while loop. I'm basically, going to come up to the guess equals int 7 00:00:31,380 --> 00:00:37,280 input line. Press over here, then I press ENTER there and I'm going to type while 8 00:00:37,280 --> 00:00:45,980 guess is not equal to answer : and then I'm going to indent all this code, 9 00:00:45,980 --> 00:00:50,460 right down to the end of the file. So I can just select it all and press tab, 10 00:00:50,460 --> 00:00:54,980 and it all gets indented, as you can see. And actually, what I'll do is, in terms of 11 00:00:54,989 --> 00:00:58,829 the print, let's change that as well. I'm going to cut that out and I'm 12 00:00:58,829 --> 00:01:03,449 going to put that on line six. We don't need to re-show that every time around 13 00:01:03,449 --> 00:01:08,220 the loop. Alright so the way we've got our code now, it's going to keep looping 14 00:01:08,220 --> 00:01:13,079 until guess equals answer. So in other words, when guess equals answer, the loop 15 00:01:13,079 --> 00:01:15,600 will be exited. So we've got a bit of tidying up to do, 16 00:01:15,600 --> 00:01:21,390 starting with the warning on line eight, and if we hover over that: name 17 00:01:21,390 --> 00:01:26,009 guess can be not defined. So guess hasn't been given a value yet, which means 18 00:01:26,009 --> 00:01:30,270 we can't use its value in the condition. So we can fix that by initializing 19 00:01:30,270 --> 00:01:37,700 guess. Let's do that after printing the answer - guess is equal to zero. 20 00:01:37,700 --> 00:01:42,509 Basically here, we want to initialize it to any number. I'll make a point of that, 21 00:01:42,509 --> 00:01:51,930 a note of that, to any number that doesn't equal the answer. Okay. So this is 22 00:01:51,930 --> 00:01:55,079 working because we're not allowing zero as a valid answer, so it's probably a good 23 00:01:55,079 --> 00:02:00,119 value to use here. Alright so what next? Well let's look on line 12. We're 24 00:02:00,120 --> 00:02:04,380 checking to see if the answer's correct. Now that we're allowing many guesses, 25 00:02:04,380 --> 00:02:07,649 we're going to be doing that check each time around the loop, and that means we 26 00:02:07,649 --> 00:02:11,038 don't know if they got the correct answer on the first guess, and therefore 27 00:02:11,038 --> 00:02:14,910 the message is currently wrong. So what I'm going to do is copy the text from 28 00:02:14,910 --> 00:02:20,489 line 21 and replace it on line 13. So come down here. I'm gonna 29 00:02:20,489 --> 00:02:23,730 copy that line. I could copy the text or the whole thing. I'll just copy the whole 30 00:02:23,730 --> 00:02:31,300 line and put it there, like so. Alright, now the other thing we need to do here, is if 31 00:02:31,300 --> 00:02:35,459 they have got the correct answer, we don't want to loop again. A break will 32 00:02:35,460 --> 00:02:40,380 break out of the loop, so let's add that after the print of Well done you guessed it, 33 00:02:40,380 --> 00:02:45,080 like so. Alright, so we're almost done at this point. Now we're getting the 34 00:02:45,090 --> 00:02:50,640 players input on line 10. That means we don't want to do it again, down here on 35 00:02:50,640 --> 00:02:56,500 line 20. In fact, all the code from line 20 onwards, can effectively be deleted. 36 00:02:56,500 --> 00:03:02,609 What I'll do now is I'll just comment that out, and essentially that's our 37 00:03:02,609 --> 00:03:06,620 solution, and basically, the code is complete. 38 00:03:06,620 --> 00:03:10,060 So let's actually test it, though, and see if it works. What we're going to do is, 39 00:03:10,079 --> 00:03:12,930 I'm going to run the program and confirm that it keeps requesting guesses until 40 00:03:12,930 --> 00:03:19,660 we get the correct answer. Alright so I know the answer's four - I'm just going to type 7, 41 00:03:19,660 --> 00:03:28,440 Please guess lower, 2, higher, 3. Obviously it's working, and 4, Well done 42 00:03:28,440 --> 00:03:32,040 you've guessed it. So clearly that's working. So that's the solution, or our 43 00:03:32,040 --> 00:03:38,520 solution. If your solution behaves in the same way, then well done. 44 00:03:38,520 --> 00:03:42,300 Now you may have written the code differently. There's often several ways 45 00:03:42,300 --> 00:03:45,960 to get the same results in almost any programming code, you care to come up 46 00:03:45,960 --> 00:03:49,980 with, so don't be worried if your code looks different to ours. And if you 47 00:03:49,980 --> 00:03:54,060 struggled to complete the challenge, also don't worry - the important thing here was 48 00:03:54,060 --> 00:03:57,420 to have a go. You'll find that my solution makes more sense, if you tried 49 00:03:57,420 --> 00:04:01,380 to solve the challenge yourself, first. More importantly, perhaps you'll also 50 00:04:01,380 --> 00:04:06,300 understand why, what you were trying, didn't work. 51 00:04:06,300 --> 00:04:09,450 Alright, now if you recall we had an optional extra part of the challenge, 52 00:04:09,450 --> 00:04:14,640 to check for zero, and break out of the loop if zero was typed. Now we can do that by 53 00:04:14,640 --> 00:04:18,630 adding an if block, after getting the players input. Let's have a go of doing 54 00:04:18,630 --> 00:04:23,060 that. So I'm gonna put that on line 12, before the test for the correct answer, 55 00:04:23,060 --> 00:04:31,560 and here I can go up and type if guess is equal to zero : break. Alright, that's 56 00:04:31,560 --> 00:04:35,490 the code. So that gives the player a way to get out of the program, if they can't 57 00:04:35,490 --> 00:04:39,360 guess the number. Now before testing that, I'm gonna increase the range of numbers 58 00:04:39,360 --> 00:04:42,930 they have to guess. Let's just test that as well, and instead of making it 10, as 59 00:04:42,930 --> 00:04:49,260 it currently is, I'm going to make that 1000. Run the program. Let's enter a few 60 00:04:49,260 --> 00:04:58,280 guesses and we know what the correct answer is - we'll say 500, Please guess higher, 750, 61 00:04:58,280 --> 00:05:05,880 Please guess lower, 625. Okay that's enough. Let's enter zero, and we can see we've successfully 62 00:05:05,880 --> 00:05:09,270 exited the program when I entered zero. Alright so that's the challenge 63 00:05:09,270 --> 00:05:13,440 completed, including the optional extra part as well. Now by the way, you should 64 00:05:13,440 --> 00:05:17,220 be able to guess the correct number within ten guesses. Now if you're not 65 00:05:17,220 --> 00:05:21,210 sure how you can do that, I did allude to it a little bit by the types of the 66 00:05:21,210 --> 00:05:27,500 numbers that I was entering, but full details will be disclosed in the next video.