双向链表的设计与实现

1.双向链表可以完成普通链表的所有操作，并且解决了普通链表逆向遍历效率低的问题。

双向链表相对于普通链表没有多大提示，需要注意的就是插入删除操作时的异常处理，

插入删除0号节点的异常，第一次插入的异常，最后一次删除的异常。

dlinklist.h文件

#pragma once
#include "stdio.h"
#include "stdlib.h"
#include "string.h"

typedef void DLinkList;

typedef struct _tag_DLinkListNode
{
	struct _tag_DLinkListNode* next;
	struct _tag_DLinkListNode* pre;
}DLinkListNode;

typedef struct _tag_DLinkList
{
	int length;
	DLinkListNode header;
	DLinkListNode* slider;
}TDLinkList;

DLinkList* DLinkList_Create();

void DLinkList_Destroy(DLinkList* list);

void DLinkList_Clear(DLinkList* list);

int DLinkList_Length(DLinkList* list);

int DLinkList_Insert(DLinkList* list, DLinkListNode* node,int pos);

DLinkListNode* DLinkList_Get(DLinkList* list,int pos);

DLinkListNode* DLinkList_Delete(DLinkList* list,int pos);



DLinkListNode* DLinkList_DeleteNode(DLinkList* list,DLinkListNode* node);

DLinkListNode* DLinkList_Reset(DLinkList* list);

DLinkListNode* DLinkList_Current(DLinkList* list);

DLinkListNode* DLinkList_Next(DLinkList* list);

DLinkListNode* DLinkList_Pre(DLinkList* list);

dlinklist.c文件

#include "dlinklist.h"

DLinkList* DLinkList_Create()
{
	TDLinkList* list = NULL;
	list = (TDLinkList*)malloc(sizeof(TDLinkList));
	memset(list, 0, sizeof(TDLinkList));
	return list;
}

void DLinkList_Destroy(DLinkList* list)
{
	TDLinkList *tmp = NULL;
	tmp = (TDLinkList *)list;
	if (NULL == list)
	{
		printf("func err DLinkList_Destroy()\n");
	}
	//2 释放头结点空间 
	if (tmp != NULL)
	{
		free(tmp);
	}
	return;
}

void DLinkList_Clear(DLinkList* list)
{
	TDLinkList *tmp = NULL;
	tmp = (TDLinkList *)list;
	if (NULL == list)
	{
		printf("func err DLinkList_Clear()\n");
	}
	//2 清空链表
	tmp->header.next = NULL;
	tmp->header.pre = NULL;
	tmp->slider = NULL;
	tmp->length = 0;

	return;
}

int DLinkList_Length(DLinkList* list)
{
	TDLinkList* rList = NULL;
	if (list == NULL)
	{
		printf("Length:list is NULL\n");
		return -1;
	}
	rList = (TDLinkList*)list;

	return rList->length;
}

DLinkListNode* DLinkList_Get(DLinkList* list, int pos)
{
	TDLinkList* rList = NULL;
	DLinkListNode* current = NULL;
	int i = 0;
	if (list == NULL || pos < 0)
	{
		printf("Get:list is NULL or pos < 0\n");
		return NULL;
	}
	rList = (TDLinkList*)list;
	current = &(rList->header);

	for (i = 0; i < pos; i++)
	{
		current = current->next;
	}

	return current->next;
}


int DLinkList_Insert(DLinkList* list, DLinkListNode* node, int pos)
{
	int ret = 0, i = 0;
	TDLinkList* sList = (TDLinkList*)list;

	if (list == NULL || node == NULL || pos < 0)
	{
		printf("Insert:list is NULL or node is NULL or pos<0");
		return -1;
	}
	DLinkListNode* current = &(sList->header);
	DLinkListNode* next = NULL;

	for (i=0;inext != NULL;i++)
	{
		current = current->next;
	}
	next = current->next;

	current->next = node;
	node->next = next;

	if (next != NULL)//当链表插入第一个元素时，需要特殊处理
	{
		next->pre = node;
	}
	node->pre = current;

	if (sList->length == 0)
	{
		sList->slider = node;//当链表插入第一个元素处理游标
	}

	//若在0位置插入，需要特殊处理，新结点next前pre指向null
	if (current == &(sList->header))
	{
		node->pre = NULL;
	}

	sList->length++;

	return ret;
}

//删除最后一个节点时需要特殊处理
DLinkListNode* DLinkList_Delete(DLinkList* list, int pos)
{
	int i = 0;
	TDLinkList* sList = (TDLinkList*)list;
	DLinkListNode* ret = NULL;

	if (list == NULL || pos < 0)
	{
		printf("Delete:list is NULL or node is NULL or pos<0");
		return NULL;
	}
	DLinkListNode* current = &(sList->header);
	DLinkListNode* next = NULL;

	for (i = 0; i < pos && current->next != NULL; i++)
	{
		current = current->next;
	}
	ret = current->next;
	next = ret->next;

	current->next = next;
	if (next != NULL)//需要特殊处理
	{
		next->pre = current;
		if (current == &(sList->header))
		{
			next->pre = NULL;
		}
	}

	if (sList->slider == ret)
	{
		sList->slider = next;
	}

	sList->length--;

	return ret;
}

DLinkListNode* DLinkList_DeleteNode(DLinkList* list, DLinkListNode* node)
{
	TDLinkList* sList = (TDLinkList*)list;
	DLinkListNode* ret = NULL;
	int i = 0;

	if (sList != NULL)
	{
		DLinkListNode* current = &(sList->header);

		//查找node在循环链表中的位置
		for (i = 0; i < sList->length; i++)
		{
			if (current->next == node)
			{
				ret = current->next;
				break;
			}
			current = current->next;
		}

		//如果ret找到，根据i去删除
		if (ret != NULL)
		{
			DLinkList_Delete(list, i);
		}
	}

	return ret;
}

DLinkListNode* DLinkList_Reset(DLinkList* list)
{
	TDLinkList* sList = (TDLinkList*)list;
	DLinkListNode* ret = NULL;

	if (sList != NULL)
	{
		sList->slider = sList->header.next;
		ret = sList->slider;
	}
	return ret;

}

DLinkListNode* DLinkList_Current(DLinkList* list)
{
	TDLinkList* sList = (TDLinkList*)list;
	DLinkListNode* ret = NULL;

	if (sList != NULL)
	{
		ret = sList->slider;
	}
	return ret;
}

DLinkListNode* DLinkList_Next(DLinkList* list)
{
	TDLinkList* sList = (TDLinkList*)list;
	DLinkListNode* ret = NULL;

	if (sList != NULL && sList->slider != NULL)
	{
		ret = sList->slider;
		sList->slider = ret->next;
	}

	return ret;

}

DLinkListNode* DLinkList_Pre(DLinkList* list)
{
	TDLinkList* sList = (TDLinkList*)list;
	DLinkListNode* ret = NULL;

	if (sList != NULL && sList->slider != NULL)
	{
		ret = sList->slider;
		sList->slider = ret->pre;
	}

	return ret;
}

main.c文件

#include "dlinklist.h"

struct Value
{
	DLinkListNode circlenode;
	int v;
};

int main()
{
	int i = 0;
	struct Value* pv;
	DLinkList* list = DLinkList_Create();

	struct Value v1, v2, v3, v4, v5;
	v1.v = 1;
	v2.v = 2;
	v3.v = 3;
	v4.v = 4;
	v5.v = 5;

	DLinkList_Insert(list, (DLinkListNode*)&v1, DLinkList_Length(list));
	DLinkList_Insert(list, (DLinkListNode*)&v2, DLinkList_Length(list));
	DLinkList_Insert(list, (DLinkListNode*)&v3, DLinkList_Length(list));
	DLinkList_Insert(list, (DLinkListNode*)&v4, DLinkList_Length(list));
	DLinkList_Insert(list, (DLinkListNode*)&v5, DLinkList_Length(list));

	for (i = 0; i < DLinkList_Length(list); i++)
	{
		pv = (struct Value*)DLinkList_Get(list, i);
		printf("%d\n", pv->v);
	}

	printf("\n");

	DLinkList_Delete(list, DLinkList_Length(list) - 1);
	DLinkList_Delete(list, 0);


	for (i = 0; i < DLinkList_Length(list); i++)
	{
		pv = (struct Value*)DLinkList_Next(list);
		printf("%d\n", pv->v);
	}

	printf("\n");

	DLinkList_Reset(list);
	DLinkList_Next(list);

	pv = (struct Value*)DLinkList_Current(list);

	printf("%d\n", pv->v);

	pv = (struct Value*)DLinkList_DeleteNode(list,(DLinkListNode*)pv);
	pv = (struct Value*)DLinkList_Current(list);
	printf("%d\n", pv->v);

	DLinkList_Pre(list);

	pv = (struct Value*)DLinkList_Current(list);
	printf("%d\n", pv->v);

	printf("Length:%d\n", DLinkList_Length(list));

	DLinkList_Destroy(list);
	system("pause");
	return 0;
}