1.双向链表的概念
1.1头节点 
1.2带头双向循环链表
注意： 哨兵位创建后，首尾连接自己
1.3双链表的初始化
// 双向链表的初始化
void ListInit(ListNode** pphead)
{// 给双链表创建一个哨兵位*pphead = ListBuyNode(-1);
}2.双向链表的打印
// 双向链表的打印
void ListPrint(ListNode* phead)
{// 遍历链表ListNode* pcur = phead->next;while (pcur != phead){// 打印printf("%d->", pcur->data);pcur = pcur->next;}printf("\n");
} 3.双向链表的尾插 
// 双向链表的尾插
void ListPushBack(ListNode* phead, ListDatatype x)
{// 创建一个存放数据的新节点ListNode* newnode = ListBuyNode(x);// 进行尾插// 新节点连接newnode->prev = phead->prev;newnode->next = phead;// 改变原来链表的连接phead->prev->next = newnode;phead->prev = newnode;
}4.双向链表的头插
void ListPushFront(ListNode* phead, ListDatatype x)
{// 创建一个存放数据的新节点ListNode* newnode = ListBuyNode(x);// 进行头插// 新节点连接newnode->prev = phead;newnode->next = phead->next;// 改变原来链表的连接phead->next->prev = newnode;phead->next = newnode;
}5.双向链表的尾删
void ListPopBack(ListNode* phead)
{assert(phead && phead->next != phead);// 进行尾删除ListNode* del = phead->prev;del->prev->next = del->next; del->next->prev = del->prev;// 释放空间free(del);del = NULL;
}6.双向链表的头删
void ListPopFront(ListNode* phead)
{assert(phead && phead->next != phead);// 进行头删除ListNode* del = phead->next;del->next->prev = phead;phead->next = del->next;// 释放空间free(del);del = NULL;
}7.双向链表的查找 
ListNode* ListFind(ListNode* phead, ListDatatype x)
{// 遍历双向链表ListNode* pcur = phead->next;while (pcur != phead){// 打印if (pcur->data == x){return pcur;}pcur = pcur->next;}// 没有找到return NULL;
} 8.双向链表在pos位置之后插入 
void ListInsret(ListNode* pos, ListDatatype x)
{assert(pos);// 创建一个存放数据的新节点ListNode* newnode = ListBuyNode(x);// 插入// 新节点连接newnode->prev = pos;newnode->next = pos->next;// 原链表连接pos->next->prev = newnode;pos->next = newnode;
}9.双向链表删除pos节点
void ListErase(ListNode* pos)
{//pos理论上来说不能为phead，但是没有参数phead，无法增加校验assert(pos);pos->prev->next = pos->next;pos->next->prev = pos->prev;free(pos);pos = NULL;
}10.双向链表的销毁
void ListDesTroy(ListNode* phead)
{assert(phead);// 遍历删除ListNode* pcur = phead->next;while (pcur != phead){ListNode* next = pcur->next;free(pcur);pcur = next;}//此时pcur指向phead，而phead还没有被销毁free(phead);phead = NULL;printf("销毁成功！");
}测试文件：
#include "List.h"void ListNodetext()
{ListNode* plist;ListInit(&plist);// 测试尾插ListPushBack(plist, 1);/*ListPrint(plist);*/ListPushBack(plist, 2);/*ListPrint(plist);*/ListPushBack(plist, 3);ListPrint(plist); // 1->2->3->// 测试头插//ListPushFront(plist, 6);//ListPrint(plist);//ListPushFront(plist, 7);//ListPrint(plist);//ListPushFront(plist, 8);//ListPrint(plist);// 测试尾删//ListPopBack(plist);//ListPrint(plist);//ListPopBack(plist);//ListPrint(plist);//ListPopBack(plist);//ListPrint(plist);// 测试头删//ListPopFront(plist);//ListPrint(plist);//ListPopFront(plist);//ListPrint(plist);//ListPopFront(plist);//ListPrint(plist);// 测试查找//ListNode* find = ListFind(plist, 30);//if (find == NULL)//{// printf("没有找到！");//}//else//{// printf("找到了！");//}// 测试pos位置之后插入//ListNode* find = ListFind(plist, 2);//ListInsret(find, 5);//ListPrint(plist);// 测试删除pos节点//ListNode* find = ListFind(plist, 3);//ListErase(find);//find = NULL;//ListPrint(plist);ListDesTroy(plist);plist = NULL;
}int main()
{ListNodetext();return 0;
}
