C示例程序更新单链表中的项目

#include <stdio.h>

#include <stdlib.h>



struct node {

   int data;

   struct node *next;

};



struct node *head = NULL;

struct node *current = NULL;



//Create Linked List

void insert(int data) {

   // Allocate memory for new node;

   struct node *link = (struct node*) malloc(sizeof(struct node));



   link->data = data;

   link->next = NULL;



   // If head is empty, create new list

   if(head==NULL) {

      head = link;

      return;

   }



   current = head;



   // move to the end of the list

   while(current->next!=NULL)

      current = current->next;



   // Insert link at the end of the list

   current->next = link;

}



void display() {

   struct node *ptr = head;



   printf("\n[head] =>");

   //start from the beginning

   while(ptr != NULL) {

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

      ptr = ptr->next;

   }



   printf(" [null]\n");

}



void update_data(int old, int new) {

   int pos = 0;



   if(head==NULL) {

      printf("Linked List not initialized");

      return;

   }



   current = head;

   while(current->next!=NULL) {

      if(current->data == old) {

         current->data = new;

         printf("\n%d found at position %d, replaced with %d\n", old, pos, new);

         return;

      }



      current = current->next;

      pos++;

   }



   printf("%d does not exist in the list\n", old);

}



int main() {

   insert(10);

   insert(20);

   insert(30);

   insert(1);

   insert(40);

   insert(56);



   display();

   update_data(40, 44);

   display();



   return 0;

}