C实现带头双向循环链表

头文件：

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

typedef int LTDataType;

typedef struct ListNode
{
    LTDataType a;
    struct ListNode* prev;
    struct ListNode* next;
}ListNode;

//创建返回链表的头节点
ListNode* ListCreat();
//销毁
void ListDestory(ListNode* plist);
//打印
void ListPrint(ListNode* plist);
//尾插
void ListPushBack(ListNode* plist, LTDataType val);
//尾删
void ListPopBack(ListNode* plist);
//创建节点
ListNode* BuyListNode(LTDataType val);
//头插
void ListPushFront(ListNode* plist, LTDataType val);
//头删
void ListPopFront(ListNode* plist);
//查找
LTDataType ListFind(ListNode* head, LTDataType val);
//在pos的位置插入(前插)
void ListInsert(ListNode* pos, LTDataType x, LTDataType val);
//删除pos的节点(前删)
void ListErase(ListNode* pos, LTDataType x);

实现：

#include"LIstNode.h"

//创建返回链表的头节点
ListNode* ListInit()
{
    ListNode* head = (ListNode*)malloc(sizeof(ListNode));
    head->next = head;
    head->prev = head;
    return head;
}
//销毁
void ListDestory(ListNode* head)
{
    assert(head);
    ListNode* cur = head->next;
    while (cur!= NULL || cur->next != NULL)
    {
        ListNode* _next = cur->next;
        free(cur);
        cur = _next;
    }
    free(head);
    head->a = 0;
    head->next = NULL;
    head->prev = NULL;
}
//打印
void ListPrint(ListNode* head)
{
    assert(head);
    ListNode* cur =head->next;
    while (cur != NULL)
    {
        printf("%d ", cur->a);
        cur = cur->next;
    }    
}
//尾插
void ListPushBack(ListNode* head, LTDataType val)
{
    assert(head);
    ListNode* New = BuyListNode(val);
    ListNode* tail = head->prev;
    tail->next = New;
    New->next = head;
    New->prev = tail;
    tail = New;
}
//创建节点
ListNode* BuyListNode(LTDataType val)
{
    ListNode* NewHead = (ListNode*)malloc(sizeof(ListNode));
    NewHead->a = val;
    NewHead->next = NULL;
    NewHead->prev = NULL;
    return NewHead;
}
//尾删
void ListPopBack(ListNode* head)
{
    ListNode* tail = head->prev;
    head->prev = tail->prev;
    tail->prev->next = head;
    tail = head->prev;
}
//头插
void ListPushFront(ListNode* head, LTDataType val)
{
    ListNode* cur = head->next;
    ListNode* New = BuyListNode(val);
    head->next = New;
    New->prev = head;
    New->next = cur;
    cur->prev = New;
}
//头删
void ListPopFront(ListNode* head)
{
    ListNode* cur = head->next;
    ListNode* _next = cur->next;
    head->next = _next;
    _next->prev = head;
}
//查找
LTDataType ListFind(ListNode* head, LTDataType val)
{
    ListNode* cur = head->next;
    int count = 1;
    while (cur != NULL)
    {
        if (cur->a == val)
            return count;
        cur = cur->next;
        ++count;
    }
    return -1;
}

//在pos的位置插入(前插)
void ListInsert(ListNode* pos, LTDataType x, LTDataType val)
{
    ListNode* New = BuyListNode(val);
    int count = 1;
    ListNode* cur = pos->next;
    while (count < x)
    {
        cur = cur->next;
        ++count;
    }
    New->prev = cur->prev;
    cur->prev->next = New;
    New->next = cur;
    cur->prev = New;
}
//删除pos的节点(前删)
void ListErase(ListNode* pos, LTDataType x)
{
    int count = 1;
    ListNode* cur = pos->next;
    while (count < x)
    {
        cur = cur->next;
        ++count;
    }
    cur->prev = cur->prev->prev;
    cur->prev->next = cur;
}