WEBVTT 00:00.700 --> 00:06.630 We've learned before that arrays are a contiguous sequence of single variables. 00:07.090 --> 00:10.500 These arrays are called one dimensional arrays. 00:10.830 --> 00:12.940 You can have more than one dimension. 00:13.340 --> 00:23.680 And let's say we wanted a two dimensional array type Gerais just call and entry to the. 00:23.910 --> 00:32.010 And just like for we have the size and we have another size. 00:32.480 --> 00:41.440 So this theory actually has 100 elements so there are 10 rows in 10 columns. 00:42.520 --> 00:49.140 The first 10 represents the number of rows and the next is the number of columns. 00:50.150 --> 00:53.440 So for each row there are 10 columns. 00:53.480 --> 00:55.560 Think of it that way. 00:55.570 --> 01:08.610 This is effectively a grid of of in this case integers that can be set that can have values k just like 01:08.790 --> 01:10.820 the one dimensional counterparts. 01:10.890 --> 01:13.240 It's also contiguous in memory. 01:13.620 --> 01:19.460 Here's my mental model for two D-Rays this here 01:23.060 --> 01:31.880 the indices start at the top left and go from right to left in the columns and from top to bottom for 01:32.070 --> 01:38.490 the rows just notice like one dimensional array is that indices start at zero. 01:39.020 --> 01:54.510 And so array that's it Ray to d of 0 0 is the very top top left element and say 01:56.780 --> 02:02.340 re to d of 0 1 02:04.920 --> 02:09.410 would be the top middle element in this example. 02:11.460 --> 02:26.700 And Ray we have two one would be the bottom middle in this example really two dimensional array is working 02:27.000 --> 02:30.260 the same as one dimensional arrays just in two directions. 02:31.240 --> 02:41.910 The indices go from zero to rolling minus one for rows and zero to column length minus one for columns. 02:41.920 --> 02:46.600 So here's how you would initialize a two dimensional array. 02:46.940 --> 02:48.690 So it's this 02:51.490 --> 02:55.980 and say we had another one let's get this well 03:00.710 --> 03:05.960 in what's called Judy it has to 03:08.640 --> 03:19.650 linked to in the row and the length three in the call games that's always row so your column is here. 03:21.680 --> 03:28.750 So here's how you'd initialize this say in three 03:31.700 --> 03:41.010 six K or six total elements in this array. 03:41.200 --> 03:41.630 Right. 03:42.910 --> 03:51.680 So in this case it would make a two dimensional array of two by three two rows and three columns of 03:51.710 --> 03:52.490 like or. 03:52.630 --> 03:53.230 Yeah. 03:53.290 --> 03:59.880 And just like I said for and one to three would be in the first row. 04:00.210 --> 04:00.790 OK. 04:01.100 --> 04:09.210 So this would go into the first row and four five six would be in the second row. 04:10.240 --> 04:18.610 And here's kind of a more intuitive way to initialize if we just say like this 04:23.650 --> 04:27.970 then this is also a good way to initialize. 04:28.330 --> 04:37.480 So you can group entire rows gather as well using these braces go even crazier than just two dimensions. 04:37.480 --> 04:40.590 We can have as many dimensions as we want it really. 04:40.600 --> 04:46.950 So we could have say hooray three like this. 04:46.960 --> 04:52.940 So do three and four. 04:52.970 --> 04:55.950 So this creates a three dimensional array. 04:56.120 --> 05:03.200 It has two rows of three by four a raise if you want to think of it that way Oregon. 05:03.200 --> 05:07.480 Think of it as having two rows three columns and four dead. 05:09.170 --> 05:15.380 If you want to think of it that way as well we won't be using anything above a two dimensional array 05:15.390 --> 05:19.570 but you can technically have as many dimensions that you want. 05:20.100 --> 05:24.290 So we'll see how those interact with pointers in the next lecture.