双链表(建立、删除、添加节点、打印)

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curses.h>
using namespace std;

typedef struct student
{
    int data;
    struct student *next;
    struct student *pre;
}dnode;

dnode *creat()
{
    dnode *head,*p,*s;
    int x,cycle=1;
    head=(dnode*)malloc(sizeof(dnode));
    p=head;
    while(cycle)
    {
        printf("\nplease input the data:");
        scanf("%d",&x);
        if(x)
        {
            s=(dnode*)malloc(sizeof(dnode));
            s->data = x;
            printf("\n %d",s->data);
            p->next = s;
            s->pre = p;
            p=s;
        }
        else cycle=0;
    }
    head = head->next;
    head->pre = NULL;
    p->next = NULL;

    return head;
}

dnode* del(dnode *head,int num)
{
    dnode *p1,*p2;
    p1=head;
    while(num!=p1->data && p1->next!=NULL)
        p1 = p1->next;

    if(num == p1->data)
    {
        if(p1 == head)
        {
            head = head->next;
            head->pre=NULL;
            free(p1);
        }
        else if(p1->next == NULL)
        {
            p1->pre->next = NULL;
            free(p1);
        }
        else
        {
            p1->pre->next = p1->next;
            p1->next->pre = p1->pre;
            free(p1);
        }
    }
    else
        printf("\n%d could not been found",num);

    return head;
}

dnode* insert(dnode *head,int num)
{
    dnode *p0,*p1;
    p1=head;
    p0=(dnode*)malloc(sizeof(dnode));
    p0->data = num;

    while(p0->data>p1->data && p1->next!=NULL)
     p1 = p1->next;

    if(p0->data <= p1->data)
    {
        if(head == p1)
        {
            p0->next = p1;
            p1->pre = p0;
            head=p0;
        }
        else
        {
            p1->pre->next = p0;
            p0->next = p1;
            p0->pre = p1->pre;
            p1->pre = p0;
        }
    }
    else //p0->data is bigest
    {
        p1->next = p0;
        p0->pre = p1;
        p0->next = NULL;
    }

    return head;
}

int length(dnode *head) //measuring the length of list
{
    int n=0;
    dnode *p;
    p=head;
    while(p)
    {
        p=p->next;
        n++;
    }
    return n;
}

int print(dnode *head) //print the list
{
    dnode *p;
    int n=0,i=1;
    n=length(head);
    printf("\nNow.These %d records are: ",n);
    p=head;
    if(!head) return -1;
    while(p)
    {
        printf("\n %d   ",p->data);
        p=p->next;
    }
}

int main (int argc, char **argv)
{
    dnode *head;
    int num,n;
    while(1)
    {
        printf("\n-----------------");
        printf("\n******Menu****** |");
        printf("\n0:exit           |");
        printf("\n1:cerat dlist    |");
        printf("\n2:delete a dnode |");
        printf("\n3:insert a dnode |");
        printf("\n4:print dlist    |");
        printf("\n-----------------");
        printf("\n please chose your number listed above(0 mease stop): ");
        scanf("%d",&num);
        switch(num)
        {
            case 0: return 0;
            case 1: head=creat(); break;
            case 2: printf("\nchose the number you want delete: ");
                    scanf("%d",&n);
                    head=del(head,n);
                    break;
            case 3: printf("\nchose the number you want insert: ");
                    scanf("%d",&n);
                    head=insert(head,n);
                    break;
            case 4: print(head);break;
            default: printf("\nyour number is invalid,please input again");break;
        }
    }
} /*  ----- End of main() ----- */