目录

引言 

一：结构定义

二：带头循环双向链表的各种操作 

1.初始化

2.创建节点 

3.尾插 

4.头插 

5.打印数据 

6.判空 

7.尾删 

8.头删 

9.查找 

10.销毁 

11.pos位置之前插入 

12.删除pos位置的值 

三：结束语 

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接下来的日子会顺顺利利，万事胜意，生活明朗-----------林辞忧

引言 

我们所知道链表有八种结构，是由循环与不循环，带头不带头，单向与双向相互组合而成的，头节点是不存储任何数据的，其中我们主要学习的为带头循环双向和无头不循环单向链表（单链表），接下来我们将深入了解关于带头循环双向链表的魅力

一：结构定义

typedef int DLDataType;
typedef struct DList
{
	struct DList* next;
	struct DList* prev;
	DLDataType data;
}DLNode;

二：带头循环双向链表的各种操作 

1.初始化

DLNode* DLInit()//初始化
{
	DLNode* phead = DLBuyNode(-1);
	phead->next = phead;
	phead->prev = phead;
	return phead;
}

2.创建节点 

DLNode* DLBuyNode(DLDataType x)//创建节点
{
	DLNode* newnode = (DLNode*)malloc(sizeof(DLNode));
	if (newnode == NULL)
	{
		perror("malloc fail");
		return NULL;
	}
	newnode->next = NULL;
	newnode->prev = NULL;
	newnode->data = x;
	return newnode;
}

3.尾插 

void DLPushBack(DLNode* phead, DLDataType x)//尾插
{
	assert(phead);
	//DLInster(phead, x);
	DLNode* newnode = DLBuyNode(x);
	DLNode* tail = phead->prev;
	tail->next = newnode;
	newnode->prev = tail;
	newnode->next = phead;
	phead->prev = newnode;
}

4.头插 

void DLPushFront(DLNode* phead, DLDataType x)//头插
{
	assert(phead);
	//DLInster(phead->next, x);
	DLNode* newnode = DLBuyNode(x);
	DLNode* next = phead->next;
	newnode->next = next;
	next->prev = newnode;
	phead->next = newnode;
	newnode->prev = phead;
}

5.打印数据 

void DLPrint(DLNode* phead)//打印数据
{
	assert(phead);
	DLNode* cur = phead->next;
	printf("guard<=>");
	while (cur != phead)
	{
		printf("%d<=>",cur->data);
		cur = cur->next;
	}
	printf("\n");
}

6.判空 

bool DLEmpty(DLNode* phead)//判空
{
	assert(phead);
	return phead->prev == phead;
}

7.尾删 

void DLPopBack(DLNode* phead)//尾删
{
	assert(phead);
	assert(!DLEmpty(phead));
	//DLErase(phead->prev);
	DLNode* tail = phead->prev;
	DLNode* tailPrev = tail->prev;
	tailPrev->next = phead;
	phead->prev = tailPrev;
	free(tail);
}

8.头删 

void DLPopFront(DLNode* phead)//头删
{
	assert(phead);
	assert(!DLEmpty(phead));
	//DLErase(phead->next);
	DLNode* del = phead->next;
	DLNode* next = del->next;
	phead->next = next;
	next->prev = phead;
	free(del);
}

9.查找 

DLNode* DLFind(DLNode* phead, DLDataType x)//查找
{
	DLNode* cur = phead->next;
	while (cur != phead)
	{
		if (cur->data == x)
		{
			return cur;
		}
		cur = cur->next;
	}
	return NULL;
}

10.销毁 

void DLDestroy(DLNode* phead)//销毁
{
	assert(phead);
	DLNode* cur = phead->next;
	while (cur != phead)
	{
		DLNode* next = cur->next;
		free(cur);
		cur = next;
	}
	free(phead);
}

11.pos位置之前插入 

void DLInster(DLNode* pos, DLDataType x)//pos位置之前插入
{
	assert(pos);
	DLNode* newnode = DLBuyNode(x);
	DLNode* Prev = pos->prev;
	Prev->next = newnode;
	newnode->prev = Prev;
	newnode->next = pos;
	pos->prev = newnode;
}

12.删除pos位置的值 

void DLErase(DLNode* pos)//删除pos位置的值
{
	assert(pos);
	DLNode* posPrev = pos->prev;
	DLNode* posnext = pos->next;
	posPrev->next = posnext;
	posnext->prev = posPrev;
	free(pos);
}

三：结束语 

可以看出带头循环双向链表这个结构设计的非常巧妙，解决了单链表找尾难的问题，大大提高了效率