Traversing link list

• Get pointer of the list head to local ptr, and traverse while ptr is not NULL.
• At least following are necessary:

#include <stdio.h>

#include <stdlib.h>

typedef struct node {

  int data;

  struct node *next;

  struct node *prev;

} NodeType;

NodeType *listHead=0, *listTail=0;

int listShow(void) {

    NodeType *ptr;

        

        ptr = listHead;

        if(ptr == 0) {
           // print "empty" and return 0;
        } 

        while (ptr) {

               printf("data = %d\n", ptr->data);

               ptr = ptr->next;

        }

    return 0;

}