我想建立一个链表，并打印出来 ，请各位帮忙看看程序错在什么地方了？
#include<stdio.h>
#include<malloc.h>

struct stu
    {
        long num;
        int age;
    struct stu * next;
};
int n;
struct stu * create()
    {
         struct stu * p,* tail;
        struct stu * head;
        n = 0;
        head = NULL;
        p=(struct stu *)malloc(sizeof(struct stu));
        printf("请输入学号、年龄：\n");
        scanf("%ld,%d",&p->num,&p->age);
        while(p->num != 0)
        {
            n++;
            if(n == 1)
                head = p;
            else
                tail->next=p;
                tail=p;
            p=(struct stu *)malloc(sizeof(struct stu));
            printf("请输入学号、年龄：\n");
            scanf("%ld %d",&p->num,&p->age);   //为什么我运行的时候只能输入2个学生的信息，输入第三个的时候vc6.0就无法控制了，输入不进去了，程序错在什么地方？
        }

        tail->next = NULL;
        return head;
    }

main()
{
    struct stu *p;
    p=create();
    while(p->next != NULL)
    {
        printf("[num]: %ld,[age]:%d",p->num,p->age);
        p=p->next;
    }

}