WEBVTT 00:01.130 --> 00:06.640 Going to continue on with our discussion of memory and talk about a very important concept called array's 00:07.320 --> 00:15.730 an array is a series of elements of the same type place continuously in memory so to us meaning they're 00:15.740 --> 00:17.220 all next to each other. 00:18.540 --> 00:26.000 Their real use is to store a large sequence of information and we'll be using them a lot in this course. 00:26.880 --> 00:39.120 Here's how do you create an array of type in we'll just call it in tray and knows these square brackets 00:39.130 --> 00:49.000 these kind of mean array and inside the square brackets we're going to have a value as to be a constant 00:49.000 --> 00:54.530 expression like the literals of five in this case or using something with the conc keyword. 00:54.640 --> 00:58.100 This is Max 5. 00:58.170 --> 01:02.200 Let's say Hey this works as well 01:05.400 --> 01:13.090 and you can access each element by using an index. 01:13.100 --> 01:25.820 So if you say array and say we want the very first one will say of 0 this noticer we're using the brackets 01:25.820 --> 01:26.750 again. 01:26.780 --> 01:32.930 So this kind of mean in index of when you kind of just using the variable and when you're declaring 01:32.930 --> 01:40.740 it it just means array K and those that we are you are not starting from is from 1. 01:40.800 --> 01:42.590 We're starting from zero. 01:42.720 --> 01:47.520 So it's something you'll have to get used to when programming in general. 01:47.610 --> 01:56.570 We start from zero not from 1 when we count arrays are the perfect example of this if we wanted to access 01:56.570 --> 01:59.600 the last element of the array we would do this. 01:59.600 --> 02:09.220 So since we know it's 5 it will always be the length the beer a minus one. 02:09.220 --> 02:22.160 So for noticed that the 0 1 2 3 4 5 elements but they're offset by 1 k. 02:22.310 --> 02:28.150 So just notice that if you want the last element of the array it's always the length of the array of 02:28.160 --> 02:32.160 5 in this case minus one. 02:32.180 --> 02:41.640 So this is always the case and 0 2 4 are called the indices of the array k. 02:42.020 --> 02:45.210 So those are the valid indices. 02:45.230 --> 02:51.090 So here is my mental model for arrays and general. 02:51.240 --> 02:59.800 So we have the array name and they're really just a bunch of empty boxes. 02:59.880 --> 03:01.460 It's really how I think of it. 03:01.540 --> 03:06.440 And again they're contiguous so that means they're all laid out next to each other. 03:06.440 --> 03:13.590 They're in a sequence K and up here are all the indices of the array. 03:13.600 --> 03:18.860 So in this case there are an number of boxes. 03:18.890 --> 03:23.880 OK so from 0 to and minus 1 are the indices. 03:24.010 --> 03:27.120 And of course inside are all the value. 03:27.190 --> 03:38.910 So whatever you know in this case for Inter it all be integers say hey. 03:39.200 --> 03:50.210 And those individual boxes are just like any other variables so this injury of 0 is really just an integer 03:51.040 --> 03:56.880 k and they're really just like any other integer variable that we've used before. 03:59.950 --> 04:02.850 So in fact you can think of it this way. 04:03.040 --> 04:10.120 And each index there is a variable of the array type that can be used just like an array just like a 04:10.120 --> 04:13.620 regular variable k. 04:13.660 --> 04:23.380 So as for initialization you can't initialize an array the same way that you can with a regular integer. 04:23.410 --> 04:27.290 Let's say so you have to do it a bit differently. 04:27.470 --> 04:29.890 And here's an example of how we could do it. 04:29.980 --> 04:41.730 So you can have one two three or five all in these kind of curly braces. 04:41.930 --> 04:51.600 K so this law actually set one in the very first position the first index to and the second and three 04:51.600 --> 04:53.560 in the third and so on. 04:54.780 --> 04:59.300 So these are all the values that all have. 04:59.330 --> 05:05.850 So what's Well we can actually do some different initializations using these. 05:05.890 --> 05:15.450 So let's say we had this this is also evaluate an initialize and it will set the first index to have 05:15.540 --> 05:20.650 value 1 and the second to be 2 and the third to be 3. 05:20.700 --> 05:25.310 The fourth will actually be zero and the fifth will be zero as well. 05:26.150 --> 05:36.860 And so actually sort of fill in the values for you and just set them to default so zero and this is 05:36.940 --> 05:42.460 can even do something like this and that will set them all to be zero. 05:42.770 --> 05:49.210 So we're always going to be using this kind of syntax for initializing our array. 05:49.220 --> 06:00.920 So let's see a concrete example of this so let's do something like this. 06:01.090 --> 06:18.050 Let's say we had this do you for us x 8 and 10 as our array values and we had these 06:23.300 --> 06:26.730 and that's just some all of the elements of the areas. 06:26.750 --> 06:30.040 See what we. 06:31.450 --> 06:34.570 Zero knows we're starting from zero. 06:34.780 --> 06:39.520 So these will be the eyes really the index k. 06:39.580 --> 06:44.220 This is why I love for loops is because they operate so well on arrays. 06:45.470 --> 06:53.040 Max gloss and we're just some each one. 06:53.080 --> 07:06.900 So we're going to access the array using each index this will get the I-F element of the array. 07:06.970 --> 07:16.140 So I will go from in this case 0 to 4 and see at some 07:24.090 --> 07:29.000 this this yet 30. 07:29.020 --> 07:29.460 Right. 07:29.470 --> 07:33.880 So that's 10 that's 10 and 10. 07:33.910 --> 07:35.170 So that's the. 07:36.790 --> 07:44.260 So arrays are very powerful and we'll be using them quite a bit in the rest of our projects that we 07:44.260 --> 07:44.860 do. 07:45.340 --> 07:50.280 So in the next lecture I want to talk about their relationships with pointers.