WEBVTT 0 00:00.230 --> 00:00.620 All right. 1 00:00.620 --> 00:05.630 So now that we've reached Step 3, we are moving onwards and upwards. 2 00:05.630 --> 00:11.780 And we're going to add a little bit more functionality to our hangman game so that it functions more, 3 00:11.780 --> 00:13.760 and more like a real game. 4 00:13.760 --> 00:21.170 So in this particular step, we're going to add the ability for the user to continue guessing again, and 5 00:21.170 --> 00:21.920 again. 6 00:21.920 --> 00:29.960 Repeating the hangman checks until they get all the letters in the word. 7 00:29.960 --> 00:37.610 So if you go ahead and right-click on solution.py, and then run that solution, we can see what the end 8 00:37.610 --> 00:40.100 result of this step will look like. 9 00:40.100 --> 00:42.410 So we have the chosen_word, 10 00:42.410 --> 00:45.380 we have the number of characters in that word, 11 00:45.380 --> 00:48.290 and then we are asked to guess a letter. 12 00:48.290 --> 00:56.600 So if I start from the beginning and I guess "c", now what we want to happen is this we're getting another 13 00:56.600 --> 00:58.400 opportunity to guess. 14 00:58.400 --> 01:04.400 And we want this to repeat by writing a while loop in our code. 15 01:04.400 --> 01:06.650 So that's TODO Number 1. 16 01:06.650 --> 01:16.190 Now the next thing we want to do is to update this for loop here, so that if we guess a previous correct 17 01:16.190 --> 01:23.160 letter such as the C in this case, when we guess another letter correctly, we want to keep the previous 18 01:23.160 --> 01:29.880 correct guess and the new letter and add all of that to our variable called display. 19 01:29.970 --> 01:37.440 Now, in contrast, let's take a look what happens at the moment if we use our current state of our 20 01:37.440 --> 01:39.300 code in main.py. 21 01:39.420 --> 01:49.380 So if I guess "a" and all the A's in aardvark gets filled in, the next time that I guess this 22 01:49.380 --> 01:58.500 word, my previous ones will be lost because I'm again checking against the current guess. 23 01:58.500 --> 02:02.460 So think about how you might solve that. 24 02:02.460 --> 02:10.110 And if you get stuck, there's always hints in the Description box for you, but there is quite a bit 25 02:10.110 --> 02:15.600 of thinking and quite a bit of struggling in this particular program that you're writing. 26 02:15.600 --> 02:21.930 But as always, it's really good when you struggle because that means you're learning something. 27 02:21.930 --> 02:27.180 If you're not struggling at all, then this part is probably too easy for you and you need to skip ahead 28 02:27.180 --> 02:28.320 quite a few days. 29 02:28.320 --> 02:35.280 But if you are struggling, then that means you are at the right stage in your programming journey and 30 02:35.280 --> 02:37.950 you will eventually get to where you want to be. 31 02:38.490 --> 02:42.510 So I'm going to go quiet now and let you have time to think. 32 02:42.510 --> 02:49.050 So pause the video, read the Description, try out the solution, run, and see if you can figure out 33 02:49.050 --> 02:51.720 these two TODOs in step three. 34 03:01.980 --> 03:04.290 All right, let's go through the solution. 35 03:04.290 --> 03:12.210 Now, if you haven't attempted to solve this, I recommend to stop, and don't watch the solution just 36 03:12.210 --> 03:12.630 yet. 37 03:12.630 --> 03:18.840 It's only worth watching the solution if you've actually tried at least for ten 20 minutes, 38 03:18.930 --> 03:25.330 because otherwise, the solution is just going to be somebody reading to you a bunch of code and 39 03:25.330 --> 03:27.970 you won't do any learning. 40 03:27.970 --> 03:35.830 And I'm really, really against this idea of spoon-fed education where we're just told what the 41 03:35.830 --> 03:41.650 answer is, because without the thinking phase, we're not truly learning, we're just repeating somebody 42 03:41.650 --> 03:42.670 else's thought. 43 03:42.670 --> 03:45.370 And the most important thing to learn is how to think. 44 03:45.370 --> 03:50.140 That's what a really valuable program of skill is. 45 03:50.290 --> 03:51.910 Okay, so I believe you. 46 03:51.910 --> 03:52.870 You've already tried it. 47 03:52.870 --> 03:55.510 Now let's see if we can go through the solution. 48 03:55.510 --> 04:00.520 So the first step is to use a while loop to get let the user guess again. 49 04:00.520 --> 04:07.750 Because at the moment once they make this one guess, then everything continues and we are at the end 50 04:07.750 --> 04:09.910 of the script. 51 04:09.910 --> 04:12.610 Now, how do we make them guess again? 52 04:12.610 --> 04:14.950 Well, we would need a while loop. 53 04:14.950 --> 04:23.080 So while some condition is True, or while some condition is False, then we want to continue running 54 04:23.080 --> 04:24.490 a block of code. 55 04:24.490 --> 04:30.850 And then when that condition switches, we skip out of the loop and we continue in our code. 56 04:30.850 --> 04:33.490 So what is going to be that condition? 57 04:33.490 --> 04:41.950 Well we can have a condition called, game_over, and we can set that to False. 58 04:42.550 --> 04:45.040 Now, we can check for that condition. 59 04:45.040 --> 04:48.340 We can say while not game over, 60 04:48.340 --> 04:53.050 so while game_over is False, we want the user to make some guesses, 61 04:53.050 --> 04:55.810 we want to update this display, 62 04:55.810 --> 05:02.410 and we also want to do the rest of the code because we need to check through the letter of their guess 63 05:02.410 --> 05:09.610 and see if we can update the display, et cetera, et cetera. So all of the rest of the code actually go into the 64 05:09.610 --> 05:11.650 while loop, and by go in, 65 05:11.650 --> 05:19.000 if you remember, it means that they get indented one step so that they're inside this while heading. 66 05:19.360 --> 05:25.360 Now when do we actually change the while loop so that they can come out of it? 67 05:25.360 --> 05:33.440 Well, if we have these blanks in our display to represent the unguessed letters, if all the unguessed 68 05:33.440 --> 05:40.130 letters are guessed and there are no more underscores, well then, at that point that's when our game 69 05:40.130 --> 05:41.150 is over, right? 70 05:41.150 --> 05:45.710 So let's add an if statement and check if display... 71 05:45.800 --> 05:56.000 And there's a really useful function in Python which is called in, and what we can do with in is we 72 05:56.000 --> 05:59.600 can check to see if something exists in something else. 73 05:59.600 --> 06:10.670 So we can say if this underscore ( _ ) is not in our display variable, 74 06:10.670 --> 06:15.410 so this string does not contain any of these underscores, 75 06:15.410 --> 06:19.400 well at that point, they've guessed everything because there's no more blanks. 76 06:19.400 --> 06:21.050 They've guessed all the letters. 77 06:21.050 --> 06:23.150 Then at this point, we can print. 78 06:23.150 --> 06:24.260 "You win." 79 06:24.620 --> 06:33.050 And that's also the right time point when we can change our game over so that we set it to, True, because 80 06:33.050 --> 06:33.830 they've won, 81 06:33.830 --> 06:35.750 therefore, game is over. 82 06:35.750 --> 06:38.960 Now we're going to define other conditions for game_over later on, 83 06:38.960 --> 06:45.890 but for now, at least, we have one place where our code can exit the while loop, which is really, 84 06:45.890 --> 06:50.690 really important when you're writing while loops, because otherwise you get into this infinite loop 85 06:50.690 --> 06:52.460 situation and that's not good. 86 06:52.460 --> 06:57.920 So let's test our first TODO and see if it does what we expect it to do. 87 06:57.920 --> 07:04.880 So aardvark, let's guess a letter, "a" a gets filled in and then it's asking us, Guess another letter. 88 07:04.880 --> 07:05.240 Right? 89 07:05.240 --> 07:08.370 So let's keep typing because we know what the word is. 90 07:08.370 --> 07:11.640 But now we encounter another issue, 91 07:11.640 --> 07:19.680 because notice how the "r" is being placed into our display variable, 92 07:19.680 --> 07:23.310 and the rest of them are filled in with blanks, 93 07:23.310 --> 07:30.690 but our previous guess, the "a" has disappeared from the display variable, and it's replaced by blanks. 94 07:30.690 --> 07:37.800 So in this particular situation, we'll never get to the state where there are no more underscores in 95 07:37.800 --> 07:45.390 the display, because each time this while loop runs, we're only ever checking one letter, which is 96 07:45.390 --> 07:47.520 the current guest letter. 97 07:47.550 --> 07:54.810 So to fix that, we have to go into TODO Number 2 and change the for loop so that we can keep the 98 07:54.810 --> 07:59.160 previous correct letters in the display string. 99 07:59.160 --> 08:00.870 So how do we do this? 100 08:00.870 --> 08:02.700 There's many ways of doing this, 101 08:02.700 --> 08:07.890 and one way of doing this is simply by creating a list. 102 08:07.920 --> 08:14.700 Now notice I'm going outside the while loop to create this list, because I want this list to accumulate 103 08:14.700 --> 08:19.620 while the loop runs, so that each time it's not being wiped blank. 104 08:19.620 --> 08:30.510 So if I create a new list here, which is called correct_letters and set it to a blank or an empty list 105 08:30.510 --> 08:39.060 like so, if this was placed inside the while loop, then every time the loop repeats, that list is 106 08:39.060 --> 08:45.030 going to be wiped to zero because of this part here in this line. 107 08:45.030 --> 08:48.180 So instead we want it to be outside the while loop. 108 08:48.180 --> 08:56.190 And now what we're going to do is if the letter that we're looping in through the word, is matching the 109 08:56.190 --> 09:03.390 guessed letter by the user, then not only do we add that letter to the display, but we also add that 110 09:03.390 --> 09:06.570 letter to our list of correct letters. 111 09:06.570 --> 09:13.390 So correct letters.append() and we're going to append this current letter that we're looping through. 112 09:13.390 --> 09:15.430 You can also append the guess. 113 09:15.430 --> 09:18.070 But at this point they are exactly equal. 114 09:18.070 --> 09:20.500 So it doesn't really matter which one you choose. 115 09:20.500 --> 09:24.040 It just depends on which you think is more readable. 116 09:24.910 --> 09:30.850 Now if we rerun this code, it doesn't really change much, right? 117 09:30.850 --> 09:34.630 If I change a letter, it's still not doing what I want. 118 09:34.630 --> 09:39.310 So what I have to do also is probably add another check. 119 09:39.310 --> 09:43.450 So I'm going to check another condition using an elif. 120 09:43.450 --> 09:50.800 So if the current guess matches the letter that we're currently looping on, then we add the letter 121 09:50.800 --> 09:55.750 to the display and if it doesn't match, then we add an underscore. 122 09:55.750 --> 09:57.940 But there's another condition we need to check. 123 09:57.940 --> 10:06.250 We need to check, elif, the current letter that we're looping in, is in the list of correct_letters. 124 10:06.250 --> 10:13.090 Because remember, if on a previous run of the while loop, a letter was guessed to be correct, then 125 10:13.090 --> 10:16.000 it gets added to this list of correct letters. 126 10:16.000 --> 10:22.330 And so now whenever we check our letters and we want to fill in the other letters in the display, we 127 10:22.330 --> 10:24.100 need to make an elif. 128 10:24.280 --> 10:26.890 So in this case, what are we going to do? 129 10:26.920 --> 10:30.790 We're going to add the current_letter to the display. 130 10:30.790 --> 10:33.160 So similar to this line here. 131 10:33.160 --> 10:38.680 So now if we rerun this code and we add a letter. 132 10:38.680 --> 10:41.560 So now "b" has been added to the display, 133 10:41.560 --> 10:43.090 let's try "n". 134 10:43.090 --> 10:47.140 So you can see now b is added but n is also added. 135 10:47.140 --> 10:49.840 So the flow goes like this. 136 10:49.840 --> 10:52.690 The four letter in chosen_word, 137 10:52.690 --> 10:56.620 the first one that gets turned into a letter is b. 138 10:56.620 --> 11:00.130 So we're checking is b equal to the guess at this point? 139 11:00.130 --> 11:00.850 Yes. 140 11:00.850 --> 11:05.230 So then we add b to the display and we add blanks to the rest of it. 141 11:05.230 --> 11:09.520 Now then the correct letter is added to this list. 142 11:09.520 --> 11:12.580 So b now lives inside this list. 143 11:12.580 --> 11:18.440 And notice it's outside the while loop so it doesn't get modified when the while loop repeats from the 144 11:18.440 --> 11:20.150 top of the block of code. 145 11:20.150 --> 11:24.080 So the next time this runs, we're guessing a different letter, 146 11:24.080 --> 11:32.000 we're guessing "n". So when n is true, then we are adding n to our display, 147 11:32.000 --> 11:39.380 but when something else is not one of the letters that we're looping in, it's not matching guess, for 148 11:39.380 --> 11:44.270 example b, but it is in fact inside the list of correct letters, 149 11:44.270 --> 11:51.290 then that letter also gets added to the display. And this might be something that you want to try and 150 11:51.290 --> 12:00.170 run in Thonny if it is confusing, but if it all makes sense, then feel free to continue to the next 151 12:00.170 --> 12:02.960 step in the game.