实现双向链表的增删改查

头文件

#pragma once
#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
typedef int LTDataType;
typedef struct ListNode {LTDataType data;struct ListNode* prev;struct ListNode* next;
} LTNode;
//void LTInit(LTNode** pphead);
// 初始化双向链表，返回头结点指针
LTNode* LTInit();
// 销毁双向链表，释放所有节点
void LTDestroy(LTNode* phead);
// 打印双向链表
void LTPrint(LTNode* phead);
// 判断链表是否为空
bool LTEmpty(LTNode* phead);
// 尾插
void LTPushBack(LTNode* phead, LTDataType x);
// 尾删
void LTPopBack(LTNode* phead);
// 头插
void LTPushFront(LTNode* phead, LTDataType x);
// 头删
void LTPopFront(LTNode* phead);
//在pos位置之后插入数据
void LTInsert(LTNode* pos, LTDataType x);
// 删除 pos 位置的节点
void LTErase(LTNode* pos);
// 查找数据 x，返回对应节点的指针
LTNode* LTFind(LTNode* phead, LTDataType x);

函数实现

#define _CRT_SECURE_NO_WARNINGS 1
#include "s.h"
// 初始化双向链表，返回头结点指针
LTNode* LTInit() {LTNode* head = (LTNode*)malloc(sizeof(LTNode));if (head == NULL) {perror("malloc failed");exit(-1);}head->next = head;head->prev = head;return head;
}// 销毁双向链表，释放所有节点
void LTDestroy(LTNode* phead) {LTNode* cur = phead->next;while (cur != phead) {LTNode* next = cur->next;free(cur);cur = next;}free(phead);
}// 打印双向链表
void LTPrint(LTNode* phead) {LTNode* cur = phead->next;while (cur != phead) {printf("%d -> ", cur->data);cur = cur->next;}printf("NULL\n");
}// 判断链表是否为空
bool LTEmpty(LTNode* phead) {return phead->next == phead;
}// 尾插
void LTPushBack(LTNode* phead, LTDataType x) {LTNode* new_node = (LTNode*)malloc(sizeof(LTNode));new_node->data = x;// 插入到尾部new_node->prev = phead->prev;new_node->next = phead;phead->prev->next = new_node;phead->prev = new_node;
}// 尾删
void LTPopBack(LTNode* phead) {if (LTEmpty(phead)) return;LTNode* tail = phead->prev;tail->prev->next = phead;phead->prev = tail->prev;free(tail);
}// 头插
void LTPushFront(LTNode* phead, LTDataType x) {LTNode* new_node = (LTNode*)malloc(sizeof(LTNode));new_node->data = x;// 插入到头部new_node->next = phead->next;new_node->prev = phead;phead->next->prev = new_node;phead->next = new_node;
}// 头删
void LTPopFront(LTNode* phead) {if (LTEmpty(phead)) return;LTNode* first = phead->next;phead->next = first->next;first->next->prev = phead;free(first);
}// 在 pos 位置之后插入数据
void LTInsert(LTNode* pos, LTDataType x) {LTNode* new_node = (LTNode*)malloc(sizeof(LTNode));new_node->data = x;new_node->next = pos->next;new_node->prev = pos;pos->next->prev = new_node;pos->next = new_node;
}// 删除 pos 位置的节点
void LTErase(LTNode* pos) {pos->prev->next = pos->next;pos->next->prev = pos->prev;free(pos);
}// 查找数据 x，返回对应节点的指针
LTNode* LTFind(LTNode* phead, LTDataType x) {LTNode* cur = phead->next;while (cur != phead) {if (cur->data == x) {return cur;}cur = cur->next;}return NULL;
}

测试文件

#define _CRT_SECURE_NO_WARNINGS 1
#include "s.h"
int main() {LTNode* list = LTInit();LTPushBack(list, 10);LTPushBack(list, 20);LTPushBack(list, 30);LTPrint(list);LTNode* pos = LTFind(list, 20);if (pos) {LTInsert(pos, 25);}LTPrint(list);LTPopBack(list);LTPrint(list);LTDestroy(list);return 0;
}

实现效果