WEBVTT 0 00:00.230 --> 00:00.620 All right. 1 00:00.620 --> 00:02.300 So how did that go? 2 00:02.330 --> 00:03.770 I hope it went really well, 3 00:03.770 --> 00:07.700 and you've managed to complete it all by yourself. If you got stuck, 4 00:07.700 --> 00:10.430 I really recommend just having a sandwich, 5 00:10.430 --> 00:13.640 have a cup of tea, take a break, and then come back to it. 6 00:13.640 --> 00:17.780 You'd be surprised what your brain can do when it just has a little bit of rest. 7 00:17.780 --> 00:23.030 But I want you to make sure that you've really given it a proper go before you come here and watch the 8 00:23.030 --> 00:28.430 solution, because I'm going to walk you through the solution step by step in case there are little 9 00:28.460 --> 00:32.830 bits or something that you didn't understand, or something that you want to check. 10 00:32.830 --> 00:37.300 But I really, really hope that you've managed to tackle most of this yourself. 11 00:37.660 --> 00:42.730 All right, so without further ado, let's get started coding up our Blackjack Project. 12 00:43.570 --> 00:47.260 Hopefully you've already used, Hints 1, 2 or 3. 13 00:47.260 --> 00:53.380 And I'm going to get started with Hint 4 and build up our Blackjack project step by step. 14 00:53.950 --> 01:02.710 Now the idea of the Hint 1, 2, and 3 is to get you to create these small TODOs of your own 15 01:02.710 --> 01:08.770 so that you can have practice breaking down the problem into a list, and then breaking it down into 16 01:08.770 --> 01:13.450 a flowchart, and then breaking it down into smaller, bite-sized TODOs. 17 01:13.540 --> 01:16.000 So let's start out with the first one. 18 01:16.060 --> 01:25.320 We have to create a deal_card() function that uses the list below to return a random card, and 11 is 19 01:25.320 --> 01:27.270 going to be the Ace in this deck. 20 01:27.870 --> 01:29.100 So let's get started. 21 01:29.100 --> 01:32.430 And we're going to go and create our deal_card() function. 22 01:32.640 --> 01:37.110 Now this function is going to contain these cards, 23 01:37.110 --> 01:39.660 so I'm going to go ahead and paste it in, 24 01:39.660 --> 01:41.070 make sure it's indented. 25 01:41.070 --> 01:43.020 So it's inside the function. 26 01:43.110 --> 01:48.780 And now I'm going to use these cards to randomly pick one out of this list. 27 01:48.780 --> 01:54.780 So to do that we can of course import our Random Module. 28 01:54.780 --> 02:02.130 And then I'm going to use random.choice() to pick a random card from my list of cards. 29 02:02.130 --> 02:06.480 And then this of course has an output, this random.choice(). 30 02:06.480 --> 02:13.680 So I'm going to save that output, namely the random card inside another variable called card. 31 02:13.770 --> 02:19.170 And then finally we're going to return this chosen card as the output. 32 02:19.200 --> 02:21.510 So that's Step 4 done. 33 02:22.650 --> 02:25.110 Now let's move on to Step 5. 34 02:25.200 --> 02:31.170 So we're going to deal the user and computer two cards each using the deal_card() function. 35 02:31.170 --> 02:39.440 And very helpfully, the hint tells us that we can start out with a blank user card and a blank computer 36 02:39.440 --> 02:40.220 card list. 37 02:40.220 --> 02:44.840 So we basically just have to add two cards to each of these lists. 38 02:44.960 --> 02:53.450 To do this, I'm going to use a for loop, and I'm going to use the range() operator to run this for loop 39 02:53.450 --> 02:54.230 twice. 40 02:54.230 --> 02:58.010 So you've seen this syntax before when we talked about for loops. 41 02:58.010 --> 03:03.160 And I've got an underscore here because we don't actually need this particular variable, 42 03:03.160 --> 03:05.980 all we need is for this loop to run twice, 43 03:05.980 --> 03:10.720 and this code is going to achieve that. Every single time this loop runs, 44 03:10.720 --> 03:14.440 we're going to get a new card by calling deal_card(). 45 03:14.560 --> 03:17.860 Now remember that deal_card() has an output. 46 03:17.860 --> 03:20.140 It outputs a random card. 47 03:20.140 --> 03:24.520 So if you want it's actually quite helpful to add some documentation to this. 48 03:24.520 --> 03:30.270 So we could say, """Returns a random card from the deck.""" 49 03:31.680 --> 03:38.490 And now when I write deal_card(), you can see that the doc tells me that this function is going to return 50 03:38.490 --> 03:40.110 a random card from the deck. 51 03:40.110 --> 03:43.650 So that random card is going to replace this function call. 52 03:43.650 --> 03:47.820 So we can capture that data by storing it inside a variable. 53 03:47.820 --> 03:56.070 So we'll call that new_card, and set it equal to the output from the function deal_card(). 54 03:56.370 --> 04:03.210 Now the next thing we're going to do is we're going to add this new_card to the user_cards. 55 04:03.210 --> 04:05.250 So at the moment it's an empty list, 56 04:05.250 --> 04:10.560 and all we have to do is say user_cards.append(), 57 04:10.560 --> 04:16.040 and then the object that we want to add to that list is going to be the new_card. 58 04:16.280 --> 04:22.220 Now, some of you might be tempted to instead use the +=, 59 04:22.430 --> 04:24.620 you might want to write something like this. 60 04:24.620 --> 04:27.920 User cards += new_card. 61 04:28.010 --> 04:31.340 And I want to show you what actually happens when you run this. 62 04:31.340 --> 04:33.410 Because this is a really common error. 63 04:33.410 --> 04:36.560 We get a Traceback, and we get a TypeError. 64 04:36.560 --> 04:45.260 It tells us that the 'int' object is not iterable and it highlights this line 49 as the reason for the 65 04:45.260 --> 04:45.740 error. 66 04:46.370 --> 04:48.140 So what's going on here? 67 04:48.170 --> 04:55.250 Well, this plus equals is actually shorthand for writing the extend() function. 68 04:55.250 --> 05:02.030 Now you can see that the extend function is something that extends a list by appending elements from 69 05:02.030 --> 05:03.050 the iterable. 70 05:03.050 --> 05:04.460 So what does this mean? 71 05:04.460 --> 05:11.500 Well, it means that whatever you put inside these parentheses, it has to be a list itself. 72 05:11.530 --> 05:21.760 For example, if this new_card was a list of cards, so maybe just the first dealt card and another 73 05:21.760 --> 05:28.750 card, or even just it by itself inside a set of square brackets which turns it into a list, 74 05:28.750 --> 05:34.810 well then if we run this code right now, we no longer have any errors. 75 05:34.810 --> 05:41.110 And if I convert this back to what you saw before, which is using the p+=, we also have no 76 05:41.110 --> 05:41.920 errors. 77 05:41.920 --> 05:48.190 But when you only want to add a single item, not a list to an existing list, then you have to use 78 05:48.190 --> 05:48.850 append(). 79 05:48.850 --> 05:53.620 So hopefully you didn't have this issue, but if you did, this is the reason. 80 05:54.190 --> 06:00.360 Now that we've created these two lines, you can see that it's a little bit redundant because we're 81 06:00.360 --> 06:05.670 creating this new_card variable just to hold the output from this function, 82 06:05.670 --> 06:10.320 and then we're immediately putting it into this list using the append(). 83 06:10.320 --> 06:19.020 So instead we can actually just get rid of the middleman and put deal_card() directly inside the append. 84 06:19.020 --> 06:23.160 And this does exactly the same thing in a single line of code. 85 06:23.430 --> 06:29.100 Once we've done this for user_cards, we'd probably want to do the same thing for the computer_cards. 86 06:29.100 --> 06:35.370 So computer_cards.append(), and then we call deal_card() again remembering the parentheses. 87 06:35.370 --> 06:38.310 So we've got a total of three parentheses at the end. 88 06:38.310 --> 06:41.490 And this way we deal a new_card 89 06:41.490 --> 06:45.450 and that new_card gets appended to the end of this list.