/* Program 12.2, p. 328 

   Insert into an ordered, singly linked list.  The arguments are a pointer
   to the first node in the list, and the value to insert. 
*/

#include <stdlib.h>
#include <stdio.h>
#include "linkedlist.h"

int insert (NODE_T **rootp, int new_value)

{
   NODE_T *current;
   NODE_T *previous;
   NODE_T *new;

   /* get the pointer to the first node */
   current = *rootp;
   previous = NULL;

   /* look for the right place by walking down the list until we reach a 
      node whose value is greater than or equal to the new value */

   while (current != NULL && current -> value < new_value) {

      previous = current;
      current = current -> next;
   }

   /* allocate a new node and store the new value in it */

   new = (NODE_T *) malloc (sizeof (NODE_T));

   if (new == NULL) 
      return FALSE;

   new -> value = new_value;

   /* insert the node into the list */

   new -> next = current;

   if (previous == NULL)

      *rootp = new;

   else

      previous -> next = new;

   return TRUE;
}