Sams Teach Yourself C in 21 Days

Deleting an Element from the List

Deleting an element from a linked list is a simple matter of manipulating pointers. The

exact process depends on where in the list the element is located:

• To delete the first element, set the head pointer to point to the second element in
  the list.


• To delete the last element, set the next pointer of the next-to-last element to NULL.


• To delete any other element, set the next pointer of the element before the one
  being deleted to point to the element after the one being deleted.
  In addition, the memory of the element that is removed from the list should be freed so
  the program does not claim more memory than it needs (this is called a memory leak).
  Freeing memory is done with the free()function, which is explained in detail on Day

20. Here’s the code to delete the first element in a linked list:
    free(head);
    head = head->next;
    This code deletes the last element in the list:
    person current1, current2;
    current1 = head;
    current2= current1->next;
    while (current2->next != NULL)
    {
    current1 = current2;

422 Day 15

FIGURE15.12

Adding a new element

to the middle of a

linked list. data

next pointer

data

next pointer

new data

NULL

data

NULL

head

Before addition

data

next pointer

data

next pointer

new data

next pointer

data

NULL

head

After addition

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