更新双向链表中的数据

实现

该算法的实现如下 −

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

struct node {
   int data;
   struct node *prev;
   struct node *next;
};

struct node *head = NULL;
struct node *last = NULL;
struct node *current = NULL;

//display the list
void printList() {
   struct node *ptr = head;

   printf("
[head] <=>");
   //从头开始
   while(ptr != NULL) {        
      printf(" %d <=>",ptr->data);
      ptr = ptr->next;
   }

   printf(" [last]
");
}

//创建链接列表
void insert(int data) {
   // 为新节点分配内存;
   struct node *link = (struct node*) malloc(sizeof(struct node));

   link->data = data;
   link->prev = NULL;
   link->next = NULL;

   // 如果 head 为空，则创建新列表
   if(head==NULL) {
      head = link;
      return;
   }

   current = head;
   
   // 移至列表末尾
   while(current->next!=NULL)
      current = current->next;

   // 在列表末尾插入链接
   current->next = link;
   last = link;
   link->prev = current;
}

void update_data(int old, int new) {
   int pos = 0;
   
   if(head == NULL) {
      printf("Linked List not initialized");
      return;
   } 

   current = head;
   while(current!=NULL) {
      pos++;
      
      if(current->data == old) {
         current->data = new;
         printf("
%d found at position %d, replaced with %d
", old, pos, new);
         return;
      }

      if(current->next != NULL)
         current = current->next;
      else
         break;
   }
   printf("%d does not exist in the list
", old);
}

int main() {
   insert(10);
   insert(20);
   insert(30);
   insert(1);
   insert(40);
   insert(56); 

   printList();
   update_data(56, 99);   
   printList();

   return 0;
}

输出

程序的输出应为 −

[head] <=> 10 <=> 20 <=> 30 <=> 1 <=> 40 <=> 56 <=> [last]

56 found at position 6, replaced with 99

[head] <=> 10 <=> 20 <=> 30 <=> 1 <=> 40 <=> 99 <=> [last]

linked_list_programs_in_c.html