WEBVTT 00:00.080 --> 00:04.310 Now let's learn the first loop, which is the while loop. 00:04.310 --> 00:11.420 So the loops are different from the if statement in the way that with the if statement. 00:11.420 --> 00:19.640 If the expression in the condition is true, the statements in the body are only run once. 00:19.670 --> 00:25.910 Now, with loops like the while loop, the statements will be run. 00:25.910 --> 00:34.520 As long as this condition is true, this might be infinite number of times. 00:34.520 --> 00:42.740 So that's also something you need to watch out for that you might just create an infinite loop. 00:42.770 --> 00:47.390 Okay, so let's see a practical example of a while loop. 00:47.450 --> 00:53.120 So back in the code editor let's create an example with the while loop. 00:53.120 --> 01:01.610 Now I would like this to be something interesting, as I don't like to learn with boring examples myself. 01:01.610 --> 01:09.820 So let's create a simple guessing game That would run in the command line, and the job of the user 01:09.820 --> 01:12.640 would be to guess our password. 01:13.030 --> 01:18.970 So we need a variable where we're going to keep this password. 01:18.970 --> 01:21.280 Let it be magic. 01:21.310 --> 01:23.080 You can come up with something else. 01:23.080 --> 01:28.690 Then let's add a variable to count the attempts that someone has made. 01:29.380 --> 01:30.730 Start with zero. 01:30.880 --> 01:37.840 Then let's decide on the maximum attempts before his luck is running out. 01:37.870 --> 01:39.250 Let it be five. 01:39.250 --> 01:41.320 And now the game. 01:41.320 --> 01:42.880 So the while loop. 01:42.880 --> 01:44.110 That was pretty simple. 01:44.110 --> 01:52.300 We've got the while keyword parentheses that's mandatory to add them, and the expression that needs 01:52.300 --> 01:54.340 to go inside the condition. 01:54.340 --> 01:56.380 So this would be rather simple. 01:56.380 --> 02:05.770 If the attempts is less than maximum attempts, we run the code that is inside this loop body. 02:06.100 --> 02:08.470 So what could this be? 02:08.470 --> 02:11.420 Well we should first start with a question. 02:11.420 --> 02:16.280 So let's give them a chance to guess the password. 02:16.280 --> 02:18.380 So we echo that on the screen. 02:18.530 --> 02:21.470 So next we need to take the input from the user. 02:21.470 --> 02:23.750 Let's store it in a variable. 02:23.750 --> 02:30.170 And we also need to forget for a second that we haven't learned about the functions yet. 02:30.200 --> 02:36.170 And the only way to accept the input would be to call this specific functions. 02:37.910 --> 02:42.710 So let me just type that and we're going to talk about this later on. 02:42.710 --> 02:51.260 So those two functions basically they take the input from the command line and trim the white spaces 02:51.740 --> 02:52.310 okay. 02:52.310 --> 02:58.700 So at this point we are asking for the password for the user to guess the password. 02:58.700 --> 03:00.110 We take his answer. 03:00.110 --> 03:10.640 And since we use this attempts to figure out if we should still let him try again, we need to increase 03:10.640 --> 03:12.260 the attempts. 03:12.770 --> 03:20.260 So in PHP you have this plus plus operator that basically is increasing an integer by one. 03:20.290 --> 03:22.030 So we need to do that. 03:22.030 --> 03:24.640 Remember about infinite loops. 03:24.640 --> 03:32.140 If we would forget to increase this attempts variable value, we might end up with a loop that just 03:32.140 --> 03:33.790 runs forever. 03:34.630 --> 03:37.510 Okay, so now we need to take some decisions. 03:37.510 --> 03:48.520 Fortunately we know the if statement so we can see if maybe the guess is identical to our secret. 03:49.750 --> 03:53.800 So if that's the case we're just gonna echo. 03:54.400 --> 03:55.510 Correct. 03:57.310 --> 04:02.380 You've unlocked the treasure. 04:04.810 --> 04:12.400 Let's add a new line character, and maybe I'm gonna put some special symbol so it looks nice. 04:13.420 --> 04:16.840 Let me search for a diamond. 04:16.960 --> 04:23.880 You can copy those characters Actors from the code resources that are always on GitHub. 04:23.910 --> 04:26.460 Now we need also an alternative. 04:26.460 --> 04:34.020 And if the attempts are equal, the max attempts. 04:34.020 --> 04:38.760 Well, we need to tell to the user that that's the end of the game. 04:38.940 --> 04:43.170 So let's do echo out of attempts. 04:45.990 --> 04:48.060 The treasure. 04:50.970 --> 04:52.740 Remains locked. 04:55.050 --> 04:56.130 Newline character. 04:56.130 --> 05:00.090 And let's also add a symbol. 05:00.120 --> 05:03.120 Um, maybe just a lock. 05:04.050 --> 05:05.670 I think this would be fine. 05:05.850 --> 05:06.450 Okay. 05:06.480 --> 05:07.560 Semicolon. 05:07.590 --> 05:10.980 Next up, an alternative. 05:10.980 --> 05:13.080 So what can be an alternative? 05:13.110 --> 05:22.260 Either someone has guessed if the guess is different than the secret, then we just check if that was 05:22.260 --> 05:23.400 the last attempt. 05:23.400 --> 05:30.440 But the alternative to this is that wasn't the last attempt and the guess was incorrect. 05:31.040 --> 05:35.030 Which leaves us with saying that someone was wrong. 05:35.030 --> 05:37.430 But he can try again. 05:37.940 --> 05:46.970 And we also should say that there are some attempts left, so attempts left equal. 05:47.000 --> 05:54.830 Now we use the concatenation operator that we already know, and let's close that in parentheses and 05:54.830 --> 06:00.050 subtract the attempts from max attempts. 06:00.050 --> 06:02.600 So we are doing just simple math here. 06:02.600 --> 06:05.480 And let's make sure we add a new line character. 06:07.340 --> 06:11.780 And this is actually the whole game. 06:11.780 --> 06:13.100 One more thing. 06:13.100 --> 06:21.530 So if someone would guess the secret then we actually need to stop this loop, because the way it works 06:21.530 --> 06:30.720 is this loop will run the code that it is inside the body for maximum of five times. 06:30.720 --> 06:32.430 We've got five attempts. 06:32.430 --> 06:39.900 But if we would like to stop this loop earlier because something has happened, like in this case someone 06:39.900 --> 06:45.000 has guessed the password, so there is no point in asking about the password. 06:45.270 --> 06:47.340 Let's say two remaining times. 06:47.370 --> 06:49.740 We can use the break statement. 06:49.740 --> 06:53.100 It will just exit this loop. 06:53.130 --> 06:55.590 Okay, so it's time to try this out. 06:55.590 --> 06:58.290 I think everything should be fine here. 06:58.290 --> 07:00.720 So the password we have it here. 07:00.720 --> 07:03.450 Let me type something that's wrong. 07:03.450 --> 07:04.320 We've got. 07:07.200 --> 07:07.710 Okay. 07:07.710 --> 07:12.540 So we are out of attempts and we see that everything worked fine here. 07:12.540 --> 07:13.560 So let me try again. 07:13.560 --> 07:17.550 But this time I'm gonna type the proper password. 07:17.550 --> 07:18.510 Magic. 07:18.840 --> 07:21.690 We've got the correct success message. 07:21.690 --> 07:24.300 And as you see, the program stopped. 07:24.300 --> 07:32.730 Which also means that this break statement has successfully, well, basically broken us out of the 07:32.730 --> 07:33.360 loop.