带头结点的双向循环链表

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带头结点的双向循环链表

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程序代码如下：

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Dlist.h

//Dlist.h

typedef int DataType;

typedef struct DListNode
{
	struct DListNode* _pNext;
	struct DListNode* _pPre;
	DataType _data;
}DListNode;


// 初始化 
void DListInit(DListNode** pHead);

// 双向链表的尾插 
void DListPushBack(DListNode* pHead, DataType data);

// 双向链表的尾删 
void DListPopBack(DListNode* pHead);

// 双向链表的头插 
void DListPushFront(DListNode* pHead, DataType data);

// 双向链表的头删 
void DListPopFront(DListNode* pHead);

// 任意位置插入 
void DListInsert(DListNode* pos, DataType data);

// 任意位置删除 
void DListErase(DListNode* pos);

// 查找值为data的结点 
DListNode* DListFind(DListNode* pHead, DataType data);

// 销毁 
void DListDestroy(DListNode** pHead);

//打印
void PrintDlist(DListNode* pHead);

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Dlist.c

//Dlist.c
#include 
#include 
#include "Dlist.h"

// 初始化 
void DListInit(DListNode** pHead)
{
	assert(pHead);

	(*pHead) = (DListNode*)malloc(sizeof(DListNode));
	(*pHead)->_pNext = (*pHead);
	(*pHead)->_pPre = (*pHead);
	(*pHead)->_data = 0;
}

DListNode* BuyNode(DataType d)
{
	DListNode* newNode = (DListNode*)malloc(sizeof(DListNode));

	if (NULL == newNode)
	{
		assert(0);
		return NULL;
	}

	newNode->_data = d;
	newNode->_pNext = NULL;
	newNode->_pPre = NULL;
	return newNode;
}

// 双向链表的尾插 
void DListPushBack(DListNode* pHead, DataType data)
{
	DListNode* newNode = BuyNode(data);
	DListNode* tail = pHead;
	while (pHead != tail->_pNext)
	{
		tail = tail->_pNext;
	}
	tail->_pNext = newNode;
	newNode->_pNext = pHead;
	pHead->_pPre = newNode;
	newNode->_pPre = tail;
}

// 双向链表的尾删 
void DListPopBack(DListNode* pHead)
{
	DListNode* tail = pHead;
	if (pHead == pHead->_pNext)
		return;
	while (pHead != tail->_pNext)
	{
		tail = tail->_pNext;
	}
	tail->_pNext = NULL;
	tail->_pPre->_pNext = pHead;
	tail->_pPre = NULL;
	free(tail);
	tail = NULL;
}

// 双向链表的头插 
void DListPushFront(DListNode* pHead, DataType data)
{
	DListNode* newNode = BuyNode(data);
	pHead->_pNext->_pPre = newNode;
	newNode->_pNext = pHead->_pNext;
	pHead->_pNext = newNode;
	newNode->_pPre = pHead;
}

// 双向链表的头删 
void DListPopFront(DListNode* pHead)
{
	DListNode* temp = NULL;
	if (pHead == pHead->_pNext)
		return;
	temp = pHead->_pNext;
	pHead->_pNext->_pPre = NULL;
	pHead->_pNext = pHead->_pNext->_pNext;
	pHead->_pNext->_pPre->_pNext = NULL;
	pHead->_pNext->_pPre = pHead;
	free(temp);
	temp = NULL;
}

// 任意位置插入 
void DListInsert(DListNode* pos, DataType data)
{
	if (pos == pos->_pNext)
	{
		DListPushFront(pos, data);
		return;
	}
	DListNode* newNode = BuyNode(data);
	pos->_pPre->_pNext = newNode;
	newNode->_pPre = pos->_pPre;
	newNode->_pNext = pos;
	pos->_pPre = newNode;
}

// 任意位置删除 
void DListErase(DListNode* pos)
{
	if (pos == pos->_pNext)
		return;
	pos->_pPre->_pNext = pos->_pNext;
	pos->_pNext->_pPre = pos->_pPre;
	pos->_pPre = NULL;
	pos->_pNext = NULL;
	free(pos);
	pos == NULL;
}

// 查找值为data的结点 
DListNode* DListFind(DListNode* pHead, DataType data)
{
	DListNode* cur = pHead;
	while (pHead != cur->_pNext)
	{
		if (data == cur->_data)
			return cur;
		cur = cur->_pNext;
	}
	return NULL;
}

// 销毁 
void DListDestroy(DListNode** pHead)
{
	assert(pHead);
	
	DListNode* cur1 = (*pHead)->_pNext;
	DListNode* cur2 = NULL;
	while ((*pHead) != cur1)
	{
		cur2 = cur1->_pNext;
		free(cur1);
		cur1 = cur2;
	}
	free((*pHead));
	(*pHead) = NULL;
}

//打印
void PrintDlist(DListNode* pHead)
{
	DListNode* cur = pHead;
	if (NULL == pHead)
	{
		printf("NULL\n");
		return;
	}
	while (pHead != cur->_pNext)
	{
		printf("%d-->", cur->_data);
		cur = cur->_pNext;
	}
	printf("%d-->%d\n", cur->_data,pHead->_data);
}

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test.c

//test.c
#include 
#include 
#include "Dlist.h"

Test()
{
	DListNode* pHead;
	// 初始化
	DListInit(&pHead);
	PrintDlist(pHead);

	// 双向链表的尾插
	DListPushBack(pHead, 6);
	DListPushBack(pHead, 7);
	DListPushBack(pHead, 8);
	DListPushBack(pHead, 9);
	DListPushBack(pHead, 10);
	PrintDlist(pHead);

	// 双向链表的尾删 
	DListPopBack(pHead);
	PrintDlist(pHead);

	// 双向链表的头插 
	DListPushFront(pHead, 4);
	DListPushFront(pHead, 3);
	DListPushFront(pHead, 2);
	DListPushFront(pHead, 1);
	DListPushFront(pHead, 1);
	PrintDlist(pHead);

	// 双向链表的头删 
	DListPopFront(pHead);
	PrintDlist(pHead);

	// 查找值为6的结点 
	DListNode* pos = DListFind(pHead, 6);

	// 任意位置插入 
	DListInsert(pos, 5);
	PrintDlist(pHead);

	// 查找值为7的结点
	pos = DListFind(pHead, 7);

	// 任意位置删除 
	DListErase(pos);
	PrintDlist(pHead);

	// 销毁 
	DListDestroy(&pHead);
	PrintDlist(pHead);
}

int main()
{
	Test();
	system("pause");
	return 0;
}

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程序运行结果如下：

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