双向链表的一些操作

//Filename:DLink.cpp
//Writed by CaoLichen
//双向链表及其操作

#include<stdio.h>
#include<stdlib.h>

//结点类型
typedef struct DNode
{
	int data;
	struct DNode *next;							//指向后继结点
	struct DNode *pre;							//指向前继结点
}DLink;

//线性表初始化
DLink *InitLink(DLink *head)
{
	head = (DLink *)malloc(sizeof(DLink));		//申请空间
	head->next = NULL;
	head->pre = NULL;
	return head;
}

//建立双向链表
void CreateLink(DLink *head, int n)
{
	DLink *tmp;
	for(; n > 0; n --){
		tmp = (DLink *)malloc(sizeof(DLink));
		printf("请输入数据：");
		scanf("%d",&(tmp->data));
		
		tmp->next = head->next;						//头插法，逆序排放
		head->next = tmp;
		tmp->pre = head;
		if(tmp->next != NULL){
			tmp->next->pre = tmp;
		}

		//head = head->next;
		
	}

	printf("建立双向链表成功！\n");
}

//打印列表
void PrintLink(DLink *head)
{
	head = head->next;
	while(head != NULL){
		printf("%d\n",head->data);
		head = head->next;
	}

	printf("打印双向列表成功！\n");
}

//删除第n个结点
int DeleteLink(DLink *head, int n)
{
	int count = 1;									//当 n=1时会出错，删除的是头结点
	while(count != n && head != NULL){
		head = head->next;
		count ++;
	}

	if(head == NULL){
		printf("删除结点出现错误！\n");				// n大于链表长度
		return 0;
	}

	head->pre->next = head->next;					//
	if(head->next != NULL){
		head->next->pre = head->pre;
	}

	free(head);										//释放空间

}

//在第n个结点后添加结点
int InsertLink(DLink *head, int n)
{
	int count = 1;
	//int num;
	DLink *tmp;
	//head = head->next;
	while(count != n && head != NULL){
		count ++;
		head = head->next;
	}

	if(head == NULL){
		printf("添加结点出现错误！\n");			// n 大于链表的长度
		return 0;
	}

	printf("请输入插入的数据：");
	tmp = (DLink *)malloc(sizeof(DLink));
	scanf("%d",&tmp->data);
	
	tmp->next = head->next;
	head->next = tmp;
	tmp->pre = head;
	if(tmp->next != NULL){
		tmp->next->pre = tmp;
	}
	
}

int main(){
	DLink *head;
	head = NULL;
	head = InitLink(head);						//双向链表初始化

	int n;
	printf("请输入数据总量：");
	scanf("%d",&n);
	CreateLink(head,n);							//建立双向链表

	PrintLink(head);							//打印线性表

	printf("请输入要删除结点位置：");
	scanf("%d",&n);
	DeleteLink(head,n);							//删除结点

	PrintLink(head);							//打印线性表

	printf("请输入要添加结点位置：");
	scanf("%d",&n);
	InsertLink(head,n);							//添加结点

	PrintLink(head);							//打印线性表

	return 0;
}