1 00:00:00,450 --> 00:00:03,660 ‫So now we're going to create our pretend function. 2 00:00:04,110 --> 00:00:11,250 ‫So with pretend we're going to create a new node and then we'll have the next pointer from the new node 3 00:00:11,250 --> 00:00:18,330 ‫be set equal to head, and then we'll have the previous pointer from the first node and the linked list 4 00:00:18,330 --> 00:00:20,430 ‫point back to the new node. 5 00:00:20,850 --> 00:00:25,950 ‫We move head over to the new node and that adds that into our linked list. 6 00:00:26,250 --> 00:00:30,510 ‫That's if we're adding this into a linked list that already has items. 7 00:00:30,960 --> 00:00:36,540 ‫But if we have an empty length list, we'll have head and tail point to that new node. 8 00:00:36,780 --> 00:00:39,320 ‫So we'll start our function out like this. 9 00:00:39,330 --> 00:00:41,010 ‫We'll pass it a value. 10 00:00:41,040 --> 00:00:46,020 ‫We'll use that value to create a node like this. 11 00:00:46,470 --> 00:00:50,730 ‫And the first situation will code for is if we have an empty linked list. 12 00:00:51,410 --> 00:00:54,530 ‫So we'll say if the length is equal to zero. 13 00:00:55,210 --> 00:01:01,030 ‫We'll have head and tail be set equal to the new node, which does this. 14 00:01:01,480 --> 00:01:07,870 ‫So now let's code for when we do have items in the length list, we'll say else and we'll build out 15 00:01:07,870 --> 00:01:09,370 ‫this statement. 16 00:01:09,730 --> 00:01:16,090 ‫So the first thing we'll do is have the next pointer from the new node point to the same node that head 17 00:01:16,090 --> 00:01:17,110 ‫is pointing to. 18 00:01:17,110 --> 00:01:18,550 ‫And that does that. 19 00:01:18,550 --> 00:01:20,530 ‫We'll do that with this line of code. 20 00:01:20,560 --> 00:01:23,170 ‫New node next equals head. 21 00:01:23,530 --> 00:01:29,110 ‫So then we want the previous pointer from the L1 node to point to the new node. 22 00:01:29,440 --> 00:01:34,660 ‫So we'll say head previous equals new node. 23 00:01:35,020 --> 00:01:37,060 ‫Do that with this line of code head. 24 00:01:37,060 --> 00:01:38,890 ‫Previous equals new node. 25 00:01:39,010 --> 00:01:41,650 ‫Then we'll move head to point to the new node. 26 00:01:42,100 --> 00:01:48,250 ‫We'll do that with this line of code head equals new node, and that adds that into our linked list. 27 00:01:48,580 --> 00:01:54,880 ‫So let's add this in with the rest of our code, and the only thing left to do is to increase the length 28 00:01:54,880 --> 00:01:55,990 ‫by one. 29 00:01:56,380 --> 00:01:59,590 ‫So we'll look at this code in a moment in VZ code. 30 00:01:59,590 --> 00:02:06,850 ‫And when we do, we're going to create a length list with two nodes with values of two and three, and 31 00:02:06,850 --> 00:02:12,700 ‫then we'll pretend a node with a value of one, and then we'll have one, two, three. 32 00:02:13,000 --> 00:02:15,970 ‫So now let's flip over and take a look at this. 33 00:02:16,670 --> 00:02:21,500 ‫So there is our pre penned member function there and I'm going to scroll up. 34 00:02:22,190 --> 00:02:29,090 ‫And in our main function, this creates our doubly linked list with two items with values of two and 35 00:02:29,090 --> 00:02:29,980 ‫three. 36 00:02:29,990 --> 00:02:34,160 ‫And this line here will print those out and I'll run this. 37 00:02:34,700 --> 00:02:39,560 ‫And you can see that we have two nodes with a values of two and three. 38 00:02:40,070 --> 00:02:43,340 ‫So now I'm going to come up here and add a line. 39 00:02:44,520 --> 00:02:48,240 ‫And this will depend a node with a value of one. 40 00:02:48,240 --> 00:02:52,500 ‫And then once again, this line will print that out and I'll run this. 41 00:02:53,170 --> 00:03:00,970 ‫And now you can see that we have nodes with a values of one, two and three and that is our function 42 00:03:01,210 --> 00:03:02,620 ‫for pre pinned.