WEBVTT 00:00.300 --> 00:06.840 And to complete this programming section, let's have a look at the race you have seen that you can 00:06.840 --> 00:08.640 store data into valuables. 00:09.060 --> 00:14.290 Now, what if you need to store 10 values, for example, 10 symbols you got from a census? 00:14.880 --> 00:17.430 And what if you need to store 8000 votes? 00:17.790 --> 00:23.450 You can guess that declaring thousand valuables in your code is not practical at all. 00:23.870 --> 00:27.900 So this is where you will use arrays are what we can also call lists. 00:28.290 --> 00:29.510 What is an array? 00:29.730 --> 00:36.280 An array is simply a collection of values that are related and share the same data type. 00:36.840 --> 00:43.200 For example, you could have an array to store all students name from a classroom, another array to 00:43.200 --> 00:47.310 store the values you read from a photoresistor, etc.. 00:47.670 --> 00:51.420 So let's create an array here in the global scope. 00:51.990 --> 00:57.090 For example, we want to store list of temperatures as integers to make it simple. 00:57.390 --> 01:03.270 But first you need the data type of the values you are going to store in the array and then you are 01:03.270 --> 01:09.840 going to create a name for the array, just like you would create a name for variable temperature. 01:10.350 --> 01:15.960 So one common practice, if you want to start the list of temperature, then you can simply go to a 01:15.990 --> 01:18.820 temperature list or temperature. 01:18.990 --> 01:19.390 All right. 01:19.440 --> 01:24.600 OK, this is basically the same thing and this will make sense for you in the future. 01:24.990 --> 01:32.940 Then you open close brackets and inside brackets, you will need to define the size of the OK. 01:32.940 --> 01:41.010 Once you declare an array in C and C++ for Arduino, you first need to put a size and this size can't 01:41.010 --> 01:42.390 be modified after what? 01:42.720 --> 01:50.400 Let's say I want five elements in my array and here I have declared a three with five integer elements, 01:50.730 --> 01:53.960 but I have not initialized the value yet. 01:54.450 --> 01:55.470 Let's compile. 01:56.600 --> 01:57.410 The Rai's. 02:00.010 --> 02:06.670 OK, and now what I can do is I can initialize so I can initialize later on in the code or directly 02:06.670 --> 02:07.240 here. 02:07.930 --> 02:12.210 So one option I have is simply to put zero into brackets. 02:12.610 --> 02:19.900 This will initialize the array so all of the elements of the array to zero and then I can modify them 02:20.530 --> 02:21.040 if I want. 02:21.040 --> 02:24.160 I can also directly set a value for each element. 02:24.520 --> 02:25.750 So we have five elements. 02:25.750 --> 02:32.310 Let's say twenty three, twenty four, fifty six, 12 and 14. 02:33.670 --> 02:43.030 And this will put all of those values in all of the indexes of the array and know how to walk with this 02:43.030 --> 02:43.330 array. 02:43.330 --> 02:46.610 So here you can initialize it to work with the array. 02:46.660 --> 02:49.160 Well I'm going to do Sanyal. 02:50.690 --> 02:51.600 But being. 02:54.920 --> 03:04.190 And let's say we want to print the print, Ellen, we want to print the value 24 fonderie to get access 03:04.430 --> 03:06.530 to an element of the array. 03:06.560 --> 03:12.980 You first need to write the name of the right temperature, the right, and then you put some brackets 03:12.980 --> 03:16.910 and you write the index of the element you want. 03:17.060 --> 03:21.090 And in programming, we start to count at zero. 03:21.170 --> 03:23.690 If you'll remember, we don't start to count at one. 03:24.080 --> 03:31.820 So here you have five numbers, but in the index for this number is zero one, two, three and four. 03:32.300 --> 03:40.640 So if I want to have the value here, I need the index one and let's load and check in the same monitor. 03:43.110 --> 03:49.230 Yes, I have the volume 24, which is the second element of the array, which is the index number one. 03:49.800 --> 03:56.420 So now pay attention to that when you use the index to make sure you don't go after the last you here, 03:56.430 --> 03:59.690 the last index will be basically the size minus one. 04:00.060 --> 04:03.360 So don't try to go over the floor then. 04:03.360 --> 04:11.310 If you want to modify a value inside the array, whether you simply to the temperature array, you put 04:11.760 --> 04:14.940 the index to, let's say I want to modify the first one. 04:15.970 --> 04:23.860 So actually, index number one would be the second element, and let's put it this will put this value 04:23.860 --> 04:28.810 inside the element of the rate which corresponds to index one. 04:29.650 --> 04:35.500 If I print again after that, you would see that the value has changed. 04:35.980 --> 04:39.560 It was so twenty four and then it is thirty. 04:40.480 --> 04:46.570 OK, so you can see how to get access to one element, how to modify one element. 04:46.840 --> 04:53.110 And then if you want to go through all of the elements of the array, well you can use the for loop 04:53.110 --> 04:54.760 that we have just discovered before. 04:55.450 --> 04:59.820 So for int I is equal to zero. 05:00.340 --> 05:07.540 So we are going to start with an index at zero and then I is lower than the size of the area. 05:07.570 --> 05:10.540 So five so here is strictly lower. 05:10.570 --> 05:10.760 OK. 05:10.780 --> 05:16.630 This is very important because you don't want to get to the value five because five will be outside 05:16.630 --> 05:24.340 of the array because we start to count at zero and then I guess plus you close the parentheses, you 05:24.340 --> 05:27.790 open a new block of code and let's say serial that. 05:28.930 --> 05:34.450 Brent L.N., so what you can do is you can do temperature. 05:36.230 --> 05:44.920 All right, open the brackets and then the index here will be high so you can use actually the counter 05:45.350 --> 05:51.410 index we use in the fall, you can use it in the block of code because this is a valuable you create. 05:51.420 --> 05:52.850 So this is a local valuable. 05:52.850 --> 05:58.250 You create all the block of code that followed so you can use the eye. 05:58.430 --> 06:03.620 And I would be equal to zero one, two, three and four and then exit. 06:03.830 --> 06:05.180 So don't forget this. 06:06.020 --> 06:11.510 I'm going to comment those two lines here so we can print out of death. 06:12.140 --> 06:15.710 Let's upload the program and let's see what we get. 06:17.880 --> 06:24.390 OK, you can see 23, which is the first one, 30, which is the second value that was modified here, 06:24.810 --> 06:26.750 and then fifty six, 12 and 14. 06:26.770 --> 06:31.040 So we have just gone through all of the elements in the area. 06:31.350 --> 06:37.620 And these we are going to use the exact same structure later on when we use multiple entities in our 06:37.620 --> 06:38.060 program. 06:38.280 --> 06:39.960 So that would be malpractice for you. 06:40.260 --> 06:48.600 OK, to rig up an array is a collection of related valuables sharing the same data to create an array, 06:48.600 --> 06:53.150 you first need to declare it and give it a size which cannot be changed afterwards. 06:53.580 --> 06:58.430 Then you can access and modify any value from using an index. 06:58.860 --> 07:05.400 Finally, using full loop is a pretty efficient way of going through all the values from an array.