1 00:00:04,700 --> 00:00:09,020 Alright, so let's revise our guessing game. specifically, what we're going to do 2 00:00:09,020 --> 00:00:13,720 is give our players another guess, and we'll do that by requesting input again. 3 00:00:13,720 --> 00:00:17,960 So at the moment, we've got the code on line 6, which tests whether the guess is 4 00:00:17,970 --> 00:00:20,910 less than answer then we print a message, "Please guess higher". We're going to add 5 00:00:20,910 --> 00:00:25,680 some code down here on line 8, and we're going to type guess equals 6 00:00:25,680 --> 00:00:30,660 int parenthesis input left and right parenthesis and then a closing 7 00:00:30,660 --> 00:00:35,129 right parenthesis. Now it's important that this line is indented at the same 8 00:00:35,129 --> 00:00:39,149 level as line 7, and in my case, you can see that it is. Both lines are part 9 00:00:39,149 --> 00:00:43,739 of the same code block and are indented to the same level. Alright, so at this 10 00:00:43,740 --> 00:00:48,000 point we've got a second guess from the player. The next step is to see if that 11 00:00:48,000 --> 00:00:52,280 guess was correct or not. So we're going to add some code on line 9 now: 12 00:00:52,280 --> 00:00:58,360 if guess is equal to answer, so two equal signs there, : 13 00:00:58,360 --> 00:01:06,740 then on the next line, print parenthesis double quotes Well done, you guessed it. 14 00:01:06,740 --> 00:01:10,000 And obviously, we've going a closing double quote and right parenthesis there. 15 00:01:10,000 --> 00:01:13,860 So we're comparing guess to answer, to see if they got the correct answer. So note 16 00:01:13,860 --> 00:01:18,360 that we have to use two equal symbols here, one on line 8 and one on line 9. 17 00:01:18,360 --> 00:01:22,380 A single equal is used when binding a variable to a value, or when 18 00:01:22,380 --> 00:01:26,020 assigning a value to a variable, if you prefer to think of it that way. 19 00:01:26,020 --> 00:01:30,640 Now when testing for equality, we use two equal signs. Okay, so that's all we need 20 00:01:30,660 --> 00:01:34,220 to do. We've used an if statement to check if they got the right answer. 21 00:01:34,220 --> 00:01:37,320 I'll leave the code like that because I want to make it clear that you don't have to 22 00:01:37,320 --> 00:01:41,700 have elif and else in your if statements. The code would benefit from an else 23 00:01:41,700 --> 00:01:45,720 clause, but we'll come back to that. Al right, so that's the second guess when 24 00:01:45,720 --> 00:01:50,260 the first guess was lower than the answer. We'll do the same thing if it was higher. 25 00:01:50,300 --> 00:01:55,360 So I'm going to come down, specifically, for the code here, and on line 13, 26 00:01:55,360 --> 00:02:00,060 type the same code in. I could copy and paste it. I'll type it in again, guess equals int 27 00:02:00,060 --> 00:02:04,800 left parenthesis input, left and right parentheses and then closing parenthesis. 28 00:02:04,800 --> 00:02:11,400 If, on the next line, guess is equal to, so two equal signs, answer : press ENTER, 29 00:02:11,400 --> 00:02:17,960 print parentheses double quotes, Well done, you guessed it. 30 00:02:17,960 --> 00:02:21,020 Alright, so we've done the same, when testing whether the guess is greater 31 00:02:21,020 --> 00:02:25,760 than the answer as well. And again, very important that you've got the correct 32 00:02:25,760 --> 00:02:28,850 indentation there, and that the code's indented nicely under the print 33 00:02:28,850 --> 00:02:31,720 statement on line 12, which we've done. 34 00:02:31,720 --> 00:02:37,340 So our if and elif blocks each contain, now, another if block. Specifically, 35 00:02:37,340 --> 00:02:40,760 that's the blocks on lines 9 to 10, and also on lines 36 00:02:40,760 --> 00:02:45,140 14 to 15. The two if statements are indented one level, at the 37 00:02:45,140 --> 00:02:50,300 same level as the other lines in the same block, as you can see. Lines 10 and 15, 38 00:02:50,300 --> 00:02:53,920 they're indented another level because they're in another block. 39 00:02:53,920 --> 00:02:59,180 Those lines will only be executed when the condition guess is equal to answer, is true. 40 00:02:59,180 --> 00:03:06,280 Alright, so let's see if this works. I'm just going to run this as opposed to debugging. 41 00:03:06,280 --> 00:03:10,640 I'm gonna start by entering 9 as the first guess, 42 00:03:10,640 --> 00:03:14,980 Please guess lower - you can see on the screen. Now there's quite a few tests to do 43 00:03:14,980 --> 00:03:18,320 here, to check every possible path through the code. So let's guess 44 00:03:18,320 --> 00:03:23,440 correctly this time. I'm going to enter 5 as the second guess. 45 00:03:23,440 --> 00:03:28,940 We get the message, Well done, you guessed it, printed by line 15. So if you're not sure why the 46 00:03:28,940 --> 00:03:32,870 message came from line 15 rather than line 10, then run the program in the 47 00:03:32,870 --> 00:03:41,420 debugger to check that. I'm going to run the program again, this time I'm gonna enter 1. 48 00:03:41,420 --> 00:03:44,300 So you can see we've got the message telling us to guess higher, 49 00:03:44,300 --> 00:03:50,200 so I'm going to enter 5 - Well done, you guessed it, on the screen, and this output came 50 00:03:50,200 --> 00:03:54,220 from line 10. And again, if you're not sure why that's the case, make sure you 51 00:03:54,220 --> 00:03:57,280 run the code through the debugger, step through the code, and you'll see that 52 00:03:57,290 --> 00:04:00,760 that's the case. Alright, the code's working when we guess correctly the 53 00:04:00,760 --> 00:04:06,700 second time, but what happens if we get the second guess wrong. Well let's test that. 54 00:04:06,700 --> 00:04:12,580 So I'm going to enter 1 again, and now I'm going to enter 9, 55 00:04:12,580 --> 00:04:17,800 and as you see, that's not really very helpful. The program's terminated without telling us what happened. 56 00:04:17,800 --> 00:04:21,519 I wanted to show that you don't have to use elif and else clauses, 57 00:04:21,519 --> 00:04:25,240 but we really should use else here, to print out a message when the second 58 00:04:25,250 --> 00:04:28,340 guess is wrong. So let's actually add the code. so I'm 59 00:04:28,340 --> 00:04:33,040 going to come up to do that on, after line 10. So I'm going to come down here. 60 00:04:33,040 --> 00:04:39,500 I'm gonna press backspace so that my else is on the same level as the if, else : enter 61 00:04:39,500 --> 00:04:48,520 print on the next line, parentheses, Sorry, you have not guessed correctly. 62 00:04:48,520 --> 00:04:53,220 And we want to do the same thing when the guess is too low, and that's down here on 63 00:04:53,220 --> 00:04:57,240 line 18, which it will be when I type it. I'm back spacing again to make sure the 64 00:04:57,240 --> 00:05:02,680 else is at the same indentation level as the if, else, print parentheses double quotes. 65 00:05:02,680 --> 00:05:05,940 And of course, that should be "You have not guessed correctly", not "You have guessed correctly" 66 00:05:05,940 --> 00:05:09,200 because of course that means the else is executed if the guess 67 00:05:09,240 --> 00:05:23,580 has not been entered correctly. Same down here, so "Sorry, you have not guessed correctly". 68 00:05:23,580 --> 00:05:28,050 Okay, we got it right in the end. Alright, so again I mentioned it but pay careful 69 00:05:28,050 --> 00:05:32,160 attention here to the indentation. The if and else keywords have to be indented to 70 00:05:32,160 --> 00:05:36,870 the same level. This now makes it very easy to see which else or elif goes with 71 00:05:36,870 --> 00:05:41,100 which if. The indentation is essential for Python to understand what we want it 72 00:05:41,100 --> 00:05:45,740 to do, but the added benefit is that it also makes the code easier for us to read. 73 00:05:45,740 --> 00:05:50,080 Alright, so we're going to run the program again now. 74 00:05:50,080 --> 00:05:54,480 I'm just going to do the same thing. In my case, I'm going to enter 1 as the first guess, 75 00:05:54,480 --> 00:05:59,840 9 as the second one, and this time we've got a message, Sorry, you have not guessed correctly. 76 00:05:59,840 --> 00:06:02,520 So run the program yourself and experiment with different values 77 00:06:02,520 --> 00:06:06,600 for your guesses. The answer's always 5, which is a bit boring, but has the 78 00:06:06,600 --> 00:06:10,260 advantage to make it easier to test the program, in other words, you know which 79 00:06:10,260 --> 00:06:16,040 messages to expect. Alright, so in the next video we'll look at more of the conditional operators. 80 00:06:16,040 --> 00:06:19,080 See you in the next video.