双向循环链表

#include<stdio.h>
#include<malloc.h>
typedef struct DuLNode 
{  
   int data;  
   struct DuLNode *prior;
   struct DuLNode *next;  
}DuLNode;  
DuLNode * InitList()  
{  
   DuLNode *head,*p,*q;  
   int a;  
   printf("创建一个链表：\n");  
   head=(DuLNode *)malloc(sizeof(DuLNode));  
   head->next=NULL;                                   
   head->prior=NULL;  
   p=head;                                              
   scanf("%d",&a);  
while(a<=0)  
{  
   printf("您所输入的数据有误,请重新输入\n");  
   scanf("%d",&a);  
}  
while(a>0)  
{  
   q=(DuLNode *)malloc(sizeof(DuLNode));  
   //q->next=NULL;  
   q->data=a;  
   q->prior=p;                                     
   p->next=q;  
   p=p->next;  
   //scanf("%d",&a);   
}  
return head;  
}  
void insert(DuLNode *p,DuLNode *q)
{
    q->prior=p;
    q->next=p->next;
    (p->next)->prior=q;
    p->next=q;
}
void delete (DuLNode *p)
{
    (p->prior)->next=p->next;
    (p->next)->prior=p->prior;
}
main()
{
    struct DuLNode *a;
    a=InitList();
    printf("输出列表");
    a=a->next;
    while(a!=NULL)
    {
        printf ("%d",a->data );
        a=a->next ; 
    }
}