带头节点的双向循环链表的基本操作

CircularList.h

#ifndef _LINKLIST_H_
#define _LINKLIST_H_

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

typedef int DataType;

typedef struct DListNode
{
	DataType data;
	struct DListNode *next;
	struct DListNode *previous;
}DListNode;

DListNode *BuyListNode(DataType data);
void DListInit(DListNode **pHead);
void DListPushBack(DListNode *pHead,DataType data);
void DListPopBack(DListNode *pHead);
void DListPushFront(DListNode *pHead, DataType data);
void DListPopFront(DListNode *pHead);
void DListInsert(DListNode *pos,DataType data);
void DListErase(DListNode *pos);
DListNode *DListFind(DListNode *pHead, DataType data);
void DListDestroy(DListNode *pHead);


#endif //_LINKLIST_H_

linklist.c

#include"CircularList.h"

//创建一个节点
DListNode *BuyListNode(DataType data)
{
	DListNode *ret = (DListNode *)malloc(sizeof(DListNode));
	if(NULL == ret)
	{
		assert(0);
	}
	else
	{
		ret->data = data;
		ret->next = NULL;
		ret->previous = NULL;
	}
	return ret;
}
//初始化
void DListInit(DListNode **pHead)
{
	assert(pHead);
	*pHead = BuyListNode(0);
	(*pHead)->next = (*pHead);
	(*pHead)->previous = *pHead;
}
//双向链表的尾插
void DListPushBack(DListNode *pHead,DataType data)
{
	DListNode *cur = NULL;
	//如果链表内只有头节点
	if(pHead->next == pHead)
	{
		cur = BuyListNode(data);
		pHead->next = cur;
		cur->previous = pHead;
		cur->next = pHead;
		pHead->previous = cur;
	}
	//如果链表内有其他节点
	else
	{
		cur = BuyListNode(data);
		pHead->previous->next  = cur;
		cur->previous = pHead->previous;
		pHead->previous = cur;
		cur->next = pHead;
	}
}
//双向链表的尾删
void DListPopBack(DListNode *pHead)
{
	DListNode *cur = NULL;//用来表示要删除的节点
	//如果链表内只有头节点，不用删除，直接返回
	if(pHead == pHead->next)
		return;
	else
	{
		cur = pHead->previous;
		pHead->previous = cur->previous;
		cur->previous->next = pHead;
		free(cur);
		cur = NULL;
	}
}
//头插
void DListPushFront(DListNode *pHead, DataType data)
{
	DListNode *cur = BuyListNode(data);
	//当链表只有头节点时
	if(pHead->next == pHead)
	{
		pHead->next = cur;
		cur->next = pHead;
		cur->previous = pHead;
		pHead->previous = cur;
	}
	else
	{
		cur->previous = pHead;
		cur->next = pHead->next;
		pHead->next ->previous = cur;
		pHead->next = cur;
	}
}
//双向链表的头删
void DListPopFront(DListNode *pHead)
{
	DListNode *cur = pHead->next;
	if(pHead->next == pHead)
		return;
	else
	{
		cur->next->previous = pHead;
		pHead->next = cur->next;
		free(cur);
		cur = NULL;
	}
}
//在任意位置插入
void DListInsert(DListNode *pos,DataType data)
{
	DListNode *cur = BuyListNode(data);
	if(NULL == pos)
		return;
	//在指定位置之后插入一个节点
	else
	{
		cur->next = pos->next;
		cur->previous = pos;
		pos->next = cur;
		cur->next->previous = cur;
	}
}
//在指定位置删除一个节点
void DListErase(DListNode *pos)
{
	if(pos == NULL)
		return ;
	else
	{
		pos->previous->next = pos->next;
		pos->next->previous = pos->previous;
		free(pos);
		pos = NULL;
	}
}
//查找Data数据的节点
DListNode *DListFind(DListNode *pHead, DataType data)
{
	DListNode *cur = pHead->next;//用来记录头节点的位置
	while(cur != pHead)
	{
		if(cur->data == data)
			return cur;
		cur = cur->next;
	}
	return NULL;
}
//销毁双向循环链表
void DListDestroy(DListNode *pHead)
{
	DListNode *cur = pHead->next;
	while(cur != pHead)
	{
		DListNode *ret = cur;
		cur = cur->next;
		free(ret);
		ret = NULL;
	}
	free(pHead);
	pHead = NULL;
}

link.c

#include"CircularList.h"

void Text()
{
	DListNode *pHead = NULL;
	DListInit(&pHead);
	DListPushBack(pHead, 1);
	DListPushBack(pHead, 2);
	DListPushBack(pHead, 3);
	//DListPopBack(pHead);
	DListPushFront(pHead, 4);
	DListPushFront(pHead, 5);
	DListPopFront(pHead);
	DListInsert(DListFind(pHead, 3),6);
    DListErase(DListFind(pHead,4));
    DListDestroy(pHead);
}

int main()
{
	Text();
	return 0;
}