线性表双链表实现

前言：

其实链表最核心的地方就是链的问题，只要把一种搞明白，后面的就不那么难了（刚开始接触链表怎么也不明白，想的多了，用的劲多了，也就慢慢理解了）

双链表的代码可以直接运行，显示出效果，代码用C语言写的，有什么问题可以评论留言，看到会回复

效果图：

#include <stdio.h>
#include <malloc.h> 

typedef int ElemType;
typedef struct DLink{
	ElemType data;						//数据域
	struct DLink *before,*next;			//前驱和后继指针 
}DLink,*DLinkList;

/*创建一个双向链表*/
DLinkList InitDLink(DLink *dl)
{
	dl = (DLinkList)malloc(sizeof(DLink));
	DLinkList newnode,oldnode=dl;
	int i = 1;
	while(i<=10)
	{
		newnode = (DLinkList)malloc(sizeof(DLink));
		oldnode->next=newnode;				//前驱指针 
		newnode->before=oldnode;			//后继指针
		newnode->data=i;			
		oldnode=newnode;
		i++;
	}
	oldnode->next=NULL;
	return dl;
}

/*求双向链表的长度*/
int LenghtDLink(DLink *dl)
{
	DLinkList LinkLenght = dl->next;
	int lenght = 0;
	while(LinkLenght)
	{
		LinkLenght = LinkLenght->next;
		lenght++;
	}
	return lenght;
}

/*双向链表插入操作*/
DLinkList InsertDLink(DLink *dl,int i,ElemType e)
{
	DLinkList newnode,oldnode=dl;
	int j = 1;
	while(oldnode && j<i)
	{
		oldnode = oldnode->next;
		j++;
	}
	if(!oldnode || j>i)
		return dl;
	newnode = (DLinkList)malloc(sizeof(DLink));		//生成新结点
	newnode->data = e;
	newnode->next = oldnode->next;
	oldnode->next = newnode;
	newnode->before = oldnode;
	return dl;
}

/*双向链表删除操作*/
DLinkList DeleteDLink(DLink *dl,int i)
{
	int lenght = LenghtDLink(dl);
	if(i<1||i>lenght)
		return dl;
	int j = 1;
	DLinkList deletenode=dl;
	while(deletenode && j<i)
	{
		deletenode = deletenode->next;
		j++;
	}
	deletenode->next = deletenode->next->next;
	deletenode->next->next->before = deletenode->next->before;
	return dl;
}

int main(void)
{
	DLink Initdl,Insertdl,Deletedl,*Initlink,*Insertlink,*Deletelink;
	Initlink = InitDLink(&Initdl);
	printf("插入数据前,双向链表长度：%d\n",LenghtDLink(Initlink));
	Initlink = Initlink->next;
	while(Initlink)
	{
		printf("前驱指针域：%p\t数据域：%d\t后继指针域：%p\n",Initlink->before,Initlink->data,Initlink->next);
		Initlink = Initlink->next;
	}
	printf("\n");
	
	
	Insertlink = InitDLink(&Insertdl);
	int address = 6;
	Insertlink = InsertDLink(Insertlink,address,666);
	printf("插入数据后,双向链表长度：%d\n",LenghtDLink(Insertlink));
	Deletelink = Insertlink;
	Insertlink = Insertlink->next;
	while(Insertlink)
	{
		printf("前驱指针域：%p\t数据域：%d\t后继指针域：%p\n",Insertlink->before,Insertlink->data,Insertlink->next);
		Insertlink = Insertlink->next;
	}
	printf("\n");
	
	
	Deletelink = DeleteDLink(Deletelink,address);
	printf("删除数据后,双向链表长度：%d\n",LenghtDLink(Deletelink));
	Deletelink = Deletelink->next;
	while(Deletelink)
	{
		printf("前驱指针域：%p\t数据域：%d\t后继指针域：%p\n",Deletelink->before,Deletelink->data,Deletelink->next);
		Deletelink = Deletelink->next;
	}
	return 0;
}