双向链表（项目建立写法，只含增删查改）

#include <iostream>
#include "ac.h" 
/* run this program using the console pauser or add your own getch, system("pause") or input loop */

int main(int argc, char** argv) {
	
	Node *head;
	while(1){
		printf("1.创建链表\n");
		printf("2.插入结点\n");
		printf("3.删除结点\n");
		printf("4.输出链表\n");
		printf("5.退出程序\n");
		
		int q = 0;
		scanf("%d",&q);
		
		switch(q){
			case 1:{
				head = creatlist();
				printf("请输入你需要创建的链表结点数：");
				int num = 0 ;
				scanf("%d",&num);
				Node *sq = head;
				printf("请依次输入结点的值（以空格相隔）：");
				for(int i = 0 ; i < num ; i ++){
					Element n = 0;
					scanf("%d",&n);
					while(sq->next != NULL) sq = sq->next;
					
					creatNode(sq,n);
				} 
				break;
			}
			
			case 2:{
				printf("请输入你要插入结点的位置：");
				int num;
				scanf("%d",&num);
				Element e;
				printf("请输入你要插入的节点的值：");
				scanf("%d",&e); 
				insert(head,num,e); 
				break;
			}
			
			case 3:{
				printf("请输入你要删除结点的位置：");
				int num;
				scanf("%d",&num);
				deleteNode(head,num); 
				break;
			}
			
			case 4:{
				print(head);
				break;
			}
			
			case 5:{
				return 0;
				break;
			}
		} 
	}
	return 0;
}

#include<iostream>
#include<malloc.h>
using namespace std;

typedef int Element;

typedef struct Node
{
	Node *pre;
	Element data;
	Node *next;
}Node;

Node *creatlist();//创建链表表头

void creatNode(Node *head,Element data);//创建链表结点并插入在head后面

void insert(Node *head, int e,Element data);//在链表第e个位置插入值为data的结点

void deleteNode(Node *head ,int e);//删除第e个位置的结点

void print(Node *head);//遍历并打印列表 

#include "ac.h"

Node *creatlist()
{
	Node *head = (Node*)malloc(sizeof(Node));
	head->next = NULL;
	head->pre = NULL;
	return head;
}

void creatNode(Node *head,Element data)
{
	Node *q = (Node*)malloc(sizeof(Node));
	q->data = data;
	q->next = head->next;
	head->next = q;
	q->pre = head;	
}

void insert(Node *head, int e,Element data)
{
	Node *q = head;
	int cn = 0;
	while(q->next != NULL && cn < e){
		q = q->next;
		cn++;
	}
	if(q->next == NULL &&cn != e){
		printf("该位置不合法\n");
		return;
	} 
	creatNode(q->pre,data);	
} 

void deleteNode(Node *head ,int e)
{
	Node *q = head;
	int cn = 0;
	while(q->next != NULL && cn < e){
		q = q->next;
		cn++;
	}
	
	if(q->next == NULL &&cn != e){
		printf("该位置不合法\n");
		return;
	} 
	
	q->next->pre = q->pre;
	
	q->pre->next = q->next;
	
	free(q); 
}

void print(Node *head)
{
	Node *q = head;
	if(q->next == NULL){
		printf("链表为空\n");
		return;
	}
	
	while(q->next != NULL){
		printf("%d ",q->next->data);
		q = q->next; 
	}
	printf("\n");
}