Page 125 - DCAP201_FUNDAMENTALS_OF_DATA_STRUCTURES

Fundamentals of Data Structures

Notes
Figure 8.17: New Node Left Pointer

Source: http://www.csie.ntu.edu.tw/~hsinmu/courses/lib/exe/fetch.php?media=dsa_12spring:
dsame_chap3.pdf

Position node right pointer points to the new node and the next node of position nodes left
pointer points to new node.

Figure 8.18: Position Node Right Pointer

Source: http://www.csie.ntu.edu.tw/~hsinmu/courses/lib/exe/fetch.php?media=dsa_12spring:
dsame_chap3.pdf
Now, let us write the code for all these three cases.

!
Caution We must update the first element pointer in the calling function, not just in the
called function. For this reason we need to send double pointer.

The following code inserts a node in the doubly linked list.
void DLLInsert(struct DLLNode **head, int data, int position) {int k =
1;
struct DLLNode *temp, *newNode;
newNode = (struct DLLNode *) malloc(sizeof ( struct DLLNode ));
if(!newNode) { //Always check for memory errors
printf (“Memory Error”);
return;
}
newNode—>data = data;
if(position == 1) { //Inserting a node at the beginning
newNode—>next = *head;
newNode—>Prev = NULL;
*head—> Prev = newNode;
*head = newNode;
return;
}

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