带头双向循环链表增删操作

头文件List.h存放函数声明

#ifndef _LIST_H
#define _LIST_H

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

typedef int LTDataType;

typedef struct ListNode{
	LTDataType _data;
	struct ListNode* _next;
	struct ListNode* _prev;
}ListNode;

typedef struct List{
	ListNode* _head;
}List;

//初始化函数
void ListInit(List* plist);
//销毁,释放函数
void ListDestroy(List* plist);

//尾插
void ListPushBack(List* plist, LTDataType x);
//尾删
void ListPopBack(List* plist);

//头插
void ListPushFront(List* plist, LTDataType x);
//头删
void ListPopFront(List* plist);

//打印函数
void ListPrint(List* plist);


#endif //_LIST_H

源文件List.c存放函数功能实现

#include "List.h"

//初始化函数
void ListInit(List* plist){
	assert(plist);
	plist->_head = (ListNode*)malloc(sizeof(ListNode));
	memset(&plist->_head->_data, 0, sizeof(LTDataType));
	plist->_head->_next = plist->_head->_prev = plist->_head;
}

//销毁,释放函数
void ListDestroy(List* plist){
	ListNode* tmp = plist->_head->_next;
	while (tmp != plist->_head){
		tmp->_next->_prev = tmp->_prev;
		tmp->_prev->_next = tmp->_next;
		free(tmp);
		tmp = plist->_head->_next;
	}
	free(plist->_head);
	plist->_head = NULL;
}

//尾插
void ListPushBack(List* plist, LTDataType x){
	ListNode* cur = (ListNode*)malloc(sizeof(ListNode));
	cur->_data = x;
	plist->_head->_prev->_next = cur;
	cur->_prev = plist->_head->_prev;
	plist->_head->_prev = cur;
	cur->_next = plist->_head;
	
}

//尾删
void ListPopBack(List* plist){
	ListNode* tmp = plist->_head->_prev;
	if (tmp != plist->_head){
		tmp->_prev->_next = tmp->_next;
		tmp->_next->_prev = tmp->_prev;
		free(tmp);
	}
}

//头插
void ListPushFront(List* plist, LTDataType x){
	ListNode* cur = (ListNode*)malloc(sizeof(ListNode));
	cur->_data = x;
	
	plist->_head->_next->_prev = cur;
	cur->_next = plist->_head->_next;
	plist->_head->_next = cur;
	cur->_prev = plist->_head;
}

//头删
void ListPopFront(List* plist){
	ListNode* tmp = plist->_head->_next;
	if (tmp != plist->_head){
		tmp->_prev->_next = tmp->_next;
		tmp->_next->_prev = tmp->_prev;
		free(tmp);
	}
}

//打印函数
void ListPrint(List* plist){
	ListNode* cur;
	printf("head<-->");
	for (cur = plist->_head->_next; cur != plist->_head; cur = cur->_next){
		printf("%d<-->", cur->_data);
	}
	printf("<-->head\n");
}

源文件main.c用来测试代码功能

#include "List.h"

int main(){
	List list;
	ListInit(&list);
	ListPushFront(&list, 7);
	ListPushFront(&list, 6);
	ListPushFront(&list, 5);
	ListPushFront(&list, 4);
	ListPopBack(&list);
	ListPopFront(&list);
	ListPrint(&list);

	ListDestroy(&list);
	system("pause");
	return 0;
}