1 00:00:00,520 --> 00:00:03,430 ‫So now we're going to code bubble sort. 2 00:00:03,820 --> 00:00:06,850 ‫So we'll pick up where we left off with this array. 3 00:00:06,850 --> 00:00:11,950 ‫Except I'll shrink this down into the corner to make room for our code. 4 00:00:12,310 --> 00:00:14,720 ‫So the function is called bubble sort. 5 00:00:14,740 --> 00:00:21,370 ‫We'll pass it this array, but we're also going to pass this the size of the array. 6 00:00:21,730 --> 00:00:28,930 ‫So if you're coming from another programming language like Java or Python or JavaScript in those programming 7 00:00:28,930 --> 00:00:36,760 ‫languages, we don't have to pass this the size, but it is something that we have to do in C++ when 8 00:00:36,760 --> 00:00:38,320 ‫we're working with arrays. 9 00:00:38,650 --> 00:00:43,780 ‫And we'll talk a little bit more about this when we go over to VS Code to run this. 10 00:00:44,320 --> 00:00:51,370 ‫So in the last video, I talked about how the first time we went through the array, we did five swaps 11 00:00:51,370 --> 00:00:57,610 ‫and we have six items, then we did four swaps and three and so on. 12 00:00:57,940 --> 00:01:04,780 ‫That means that one of our four loops has to be decremental, and that's going to be this first for 13 00:01:04,780 --> 00:01:05,290 ‫loop. 14 00:01:05,650 --> 00:01:11,350 ‫We start out with I being equal to the size minus one. 15 00:01:11,680 --> 00:01:19,270 ‫So size in this case is six, which means I to begin with is going to be set to five and then we're 16 00:01:19,270 --> 00:01:25,390 ‫going to decrement this for loop and the next time will be four and three and so on. 17 00:01:25,810 --> 00:01:31,180 ‫And then we'll use I in the next for loop like this. 18 00:01:31,540 --> 00:01:37,930 ‫So this four loop will run five times the first time and then four and three and so on. 19 00:01:38,320 --> 00:01:46,240 ‫And then inside of this four loop, we'll say if array at the index of J and in the first iteration 20 00:01:46,240 --> 00:01:54,610 ‫that will be this item if it is greater than array at the index of J plus one, which is this item, 21 00:01:54,970 --> 00:02:02,080 ‫then we're going to want to swap these two items and we'll do that with these three lines of code. 22 00:02:02,380 --> 00:02:04,150 ‫So let's walk through these. 23 00:02:04,180 --> 00:02:09,430 ‫We'll say temp is equal to array at the index of J. 24 00:02:09,430 --> 00:02:14,350 ‫So we're saying temp is equal to four in this case. 25 00:02:14,650 --> 00:02:17,470 ‫And then we'll say array at the index of J. 26 00:02:17,500 --> 00:02:18,850 ‫That's that first item. 27 00:02:18,850 --> 00:02:26,080 ‫We're going to set that to be equal to array at the index of J plus one, which does this. 28 00:02:26,380 --> 00:02:32,140 ‫And then we'll set array at the index of J plus one to be equal to temp. 29 00:02:32,650 --> 00:02:33,610 ‫Like that. 30 00:02:33,610 --> 00:02:36,520 ‫And that swaps those two items. 31 00:02:37,240 --> 00:02:40,570 ‫And that is all of the code for bubble sort. 32 00:02:40,930 --> 00:02:47,410 ‫If we continue running, these four loops will eventually make the entire array look like this. 33 00:02:47,830 --> 00:02:50,980 ‫So we'll look at this code in a moment in VTS code. 34 00:02:50,980 --> 00:02:57,220 ‫And when we do, we'll start out with an array that looks like this and then we'll sort it. 35 00:02:57,670 --> 00:03:00,940 ‫So now let's flip over and take a look at this. 36 00:03:01,540 --> 00:03:04,540 ‫So there is our bubble sort function there. 37 00:03:04,900 --> 00:03:06,610 ‫And I'll scroll up. 38 00:03:06,850 --> 00:03:11,230 ‫And in our main function, this is the array that we're going to sort. 39 00:03:11,650 --> 00:03:16,390 ‫And we're going to use this line here to figure out the size of the array. 40 00:03:16,810 --> 00:03:25,150 ‫So when you say size of my array, what is going to be returned is the number of bytes in the array. 41 00:03:25,600 --> 00:03:28,090 ‫Integers are four bytes. 42 00:03:28,390 --> 00:03:33,670 ‫So that's going to return 24 because we have six items in the array. 43 00:03:34,000 --> 00:03:38,080 ‫So we have to divide this by one of the items in the array. 44 00:03:38,080 --> 00:03:41,830 ‫So we'll say size of my array at the index of zero. 45 00:03:41,860 --> 00:03:45,250 ‫One item in the array is going to be four bytes. 46 00:03:45,580 --> 00:03:48,670 ‫And that will give us the size of the array. 47 00:03:49,060 --> 00:03:54,880 ‫And the reason you have to do that is when you come down here and call the function bubble sort and 48 00:03:54,880 --> 00:03:56,980 ‫we pass it my array. 49 00:03:57,010 --> 00:04:04,030 ‫The only thing that you're passing this function when you pass it, my array is the address of this 50 00:04:04,030 --> 00:04:06,160 ‫first item in the array. 51 00:04:06,640 --> 00:04:11,060 ‫And when you pass it the array, you are not also passing the size. 52 00:04:11,080 --> 00:04:13,600 ‫You have to do that separately. 53 00:04:13,990 --> 00:04:19,060 ‫So you will see that we'll do something similar to this with all of our sorting algorithms. 54 00:04:19,480 --> 00:04:27,520 ‫So I want to emphasize, when we run bubble sort on my array, we are not returning a new array. 55 00:04:27,670 --> 00:04:34,390 ‫We are sorting this existing array in place and making this array sorted. 56 00:04:34,780 --> 00:04:41,410 ‫So down here at the bottom of our main function, we have this for loop that is going to loop through 57 00:04:41,410 --> 00:04:46,090 ‫my array and then output the values from that array. 58 00:04:46,760 --> 00:04:48,350 ‫So now I'll run this. 59 00:04:49,130 --> 00:04:54,050 ‫And you can see that my array has now been sorted one through six. 60 00:04:54,910 --> 00:04:56,710 ‫And that is our function. 61 00:04:57,470 --> 00:04:58,790 ‫For bubble sort.