WEBVTT 00:00.180 --> 00:06.210 So far, you have seen that all the instructions you write in and out a program will be executed one 00:06.210 --> 00:13.140 by one, the key line to be executed and then laid three and I'm falling five, etc. But as you progress, 00:13.140 --> 00:19.650 you will want to make your program more dynamic and you will want to be able to execute only some instructions, 00:19.930 --> 00:22.990 depending on some conditions that you test. 00:23.390 --> 00:30.690 For example, you might do a certain action if a push button is priced and if it's not pressed, you 00:30.690 --> 00:32.010 would do another action. 00:32.220 --> 00:35.970 So let's write our first condition to understand how it works. 00:36.220 --> 00:40.410 So let's create a viable in the voice set, let's say temperature. 00:40.410 --> 00:45.280 We will use integer, OK, to make it simpler and let's see 30 degrees. 00:45.660 --> 00:52.350 So as you can see, this variable is declared inside the setup function, which means that the label 00:52.350 --> 00:57.990 is local to the set of function and we won't be able to use it like that in the loop function because 00:57.990 --> 00:59.170 this is a different scope. 00:59.490 --> 00:59.880 Don't know. 00:59.880 --> 01:04.640 Let's say we want to check if the temperature is equal to some value. 01:04.920 --> 01:12.360 Well, to create a condition, you can just use if the if you want or it should green then space and 01:12.360 --> 01:17.510 then you will open parenthesis and introduces, you will make a test. 01:17.980 --> 01:19.800 I'm just going to write one. 01:19.980 --> 01:24.830 Temperature is equal to, let's say, 20 degrees. 01:25.350 --> 01:25.730 All right. 01:25.740 --> 01:30.730 And you can see to test the equality we need to put to equal sign. 01:30.780 --> 01:34.710 OK, one equal sign is to assign a value. 01:34.710 --> 01:42.180 So to assign the value from the right to the step on the left to equal sine will simply test if the 01:42.180 --> 01:44.670 value on the left is equal to the value on the right. 01:44.940 --> 01:51.810 And if it's this, we return a boolean, which value is true, and if not, it will return boolean, 01:51.810 --> 01:53.520 which value is false. 01:54.010 --> 02:00.960 So now you have written your IFPRI the condition in parentheses you can go back to a new line and open 02:00.960 --> 02:09.450 close brackets so you can either open the brackets here or here on the same line as if this is just 02:09.450 --> 02:16.230 a matter of preference and readability, though not if the temperature is exactly equal to 20. 02:16.410 --> 02:18.890 And we are going to do some action here. 02:19.020 --> 02:23.720 OK, if not, then the block of code here will not be executed. 02:24.570 --> 02:26.250 Let's say say OK, print Ellen. 02:27.360 --> 02:31.110 Let's put simply, OK, let's run that program. 02:31.320 --> 02:35.420 So first we need of course, to to been. 02:41.760 --> 02:42.510 Conditions. 02:45.980 --> 02:52.520 And as you will see, well, nothing gets executed here if we use 30. 02:55.420 --> 03:04.270 We will see, OK, because the conditions here will be evaluated to true, OK, so this is great because 03:04.270 --> 03:10.410 it means you can decide to execute this block of code only if the condition here is true. 03:10.750 --> 03:12.820 So you have different operators. 03:12.820 --> 03:19.800 You have the equal equal which will test the equality, then you might want to test the inequality. 03:20.170 --> 03:24.080 In this case, you will use exclamation mark and equal. 03:24.700 --> 03:32.040 So if the temperature is different than 30 degrees of any value but here, which is different than 30, 03:32.350 --> 03:33.660 this condition would be true. 03:33.670 --> 03:35.740 And we enter this book of code. 03:36.010 --> 03:42.750 Now, you can also test with the lower than this mean strictly lower then. 03:43.510 --> 03:49.660 So if the temperature here is equal to 29 or lower, then this will work. 03:49.870 --> 03:55.210 If it's equal to 30, it will not work because this means strictly lower. 03:55.210 --> 03:58.270 Then then you have the lower are equal. 03:58.300 --> 04:01.990 So this is the bracket plus equals sign. 04:02.320 --> 04:11.440 And if the temperature is 30, that will also what you can test also with greater than the temperature 04:11.440 --> 04:13.430 is strictly greater than 30. 04:13.480 --> 04:20.180 So starting at 31, you can test with the greater are equal than 30. 04:20.560 --> 04:23.680 Now this will test just one condition. 04:23.830 --> 04:29.190 You might want to test different conditions and combine them together. 04:29.500 --> 04:36.490 For example, if you want to check if the temperature is between 20 and 29, what you could do is check 04:36.490 --> 04:42.610 first if the temperature is greater or equal than 20. 04:43.830 --> 04:54.210 OK, and then you can use what we call end Kastel to ampersands, this will combine two conditions, 04:54.690 --> 05:01.960 but you need to put this into parenthesis here and then put another condition to Currentzis and let's 05:01.960 --> 05:03.270 say temperature. 05:04.310 --> 05:06.260 Is lower than. 05:07.660 --> 05:12.140 Urges a strictly lower and well what this will do. 05:12.160 --> 05:19.180 So you entered the chief and then you see that you have and between two conditions that this condition 05:19.180 --> 05:20.190 will be evaluated. 05:20.620 --> 05:26.650 But if the temperature is greater or equal than 20 and then this one will be evaluated and still the 05:26.650 --> 05:33.460 temperature is strictly lower than 30 and then and will basically return true for the whole condition. 05:33.820 --> 05:41.340 If both conditions are true, if I put 25, this will work because this is true. 05:42.210 --> 05:43.600 OK, this is true. 05:43.870 --> 05:46.810 And thus the whole stuff is true. 05:46.810 --> 05:48.390 And then we enter this book of code. 05:48.910 --> 05:51.490 So we are going to see that also later. 05:51.940 --> 05:59.640 So you have the end operator, which will be true only if everything is true and you have the operator, 05:59.950 --> 06:01.660 but you can use two pipes. 06:02.440 --> 06:09.880 And with this operator, the whole condition will be true if at least one of the conditions is true. 06:10.630 --> 06:15.040 So if this condition is true, let's say but 35 now. 06:15.520 --> 06:17.420 So the temperature is greater than 20. 06:17.450 --> 06:21.160 OK, this is true that this condition will be false. 06:22.360 --> 06:28.320 But then with the operator, because this condition is true, then this one can be true or false. 06:28.330 --> 06:29.110 It doesn't matter. 06:29.350 --> 06:33.050 The whole condition will be true and is a book of good will be executed. 06:33.430 --> 06:33.840 All right. 06:33.850 --> 06:35.230 And that's not all. 06:35.230 --> 06:36.730 We have the conditions. 06:37.390 --> 06:43.240 We have a simple if in any condition here, you are going to test something and execute this block of 06:43.240 --> 06:50.000 code, but maybe you can also decide to execute something if the condition is not true. 06:50.020 --> 06:58.480 OK, so if this is false, then you can use the false statements just after the if block here. 06:58.960 --> 07:04.570 You create a new block of code and this will be executed in the condition here is false. 07:04.990 --> 07:07.620 Let's just put a simple condition. 07:07.840 --> 07:08.770 Temperature. 07:10.150 --> 07:15.220 Is equal to Secretary Kerry Prince, OK, and if. 07:18.280 --> 07:22.810 It's not funny we print not poking, it's upload in code. 07:23.710 --> 07:24.810 Let's see what happens. 07:27.220 --> 07:29.750 Not OK, but what happened here? 07:29.830 --> 07:30.800 We entered. 07:30.820 --> 07:34.180 If we check the condition, the condition is false. 07:34.180 --> 07:36.380 So we don't enter this book of code. 07:36.700 --> 07:38.290 Instead, we go to the ELLSON. 07:38.290 --> 07:39.600 We enter this block of code. 07:39.850 --> 07:43.980 And what you can also do is add intermediate blocks else. 07:44.080 --> 07:46.570 If so, what you can do. 07:47.740 --> 07:50.170 Is to test different conditions. 07:53.770 --> 08:00.160 So let's say we want to first test if the temperature is 40, then we print these and then the hold 08:00.700 --> 08:03.970 if as if a structure is over. 08:04.000 --> 08:06.900 So after this, we just go to line 50. 08:07.240 --> 08:12.540 But if this condition is not true, then we are going to test the next one. 08:12.760 --> 08:15.550 If this condition is true, we enter this block of code. 08:19.090 --> 08:21.670 And then it's as if. 08:23.770 --> 08:25.060 And let's see what happens. 08:28.120 --> 08:33.210 OK, we see it because this condition is false, which is the signal on this condition is true. 08:33.490 --> 08:37.300 And then we prayed that if I use another value. 08:40.700 --> 08:45.920 You can see we test for the condition here and then the condition here and then because none of the 08:45.920 --> 08:50.750 condition is true, we don't under any block of code and we enter the else block of code. 08:50.930 --> 08:51.350 All right. 08:51.350 --> 08:58.160 And one more thing to know is also, again, to pay attention to this code here, the number two available 08:58.160 --> 09:00.800 with created in the scope of this set to function. 09:00.830 --> 09:05.120 OK, you can see here we have curly brackets, which means this is a new school. 09:05.270 --> 09:06.890 This is a nested scope. 09:07.190 --> 09:12.950 So we can use the term approach available inside the scope if you want, because it is nested compared 09:12.950 --> 09:15.920 to the scope where the temperature was created. 09:16.790 --> 09:24.530 So to recap and conditions, you will use a structure when you want to do a different action depending 09:24.530 --> 09:27.620 on some conditions that you want to test.