建立简单动态链运行后没有结果（C语言）在线等。谢谢！

Question

#include<stdio.h>

#include<stdlib.h>

#define LEN sizeof(struct student)

struct student

{

    long num;

    float score;

    struct student *next;

};

int n;

struct student *creat(void)

{

    struct stduent *head;

    struct student *p1,*p2;

    n=0;

    p1=p2=(struct student *) malloc(LEN);

    scanf("%ld,%f",&p1->num,&p1->score);

    head=NULL;

    while(p1->num!=0)

    {

        n=n+1;

        if(n==1) head=p1;

        else p2->next=p1;

        p2=p1;

        p1=(struct student *) malloc(LEN);

        scanf("%ld,%f",&p1->num,&p1->score);

    }

    p2->next=NULL;

    return (head);

}

int main()

{

    struct student *pt;

    pt=creat();

    printf("\n num:%ld\n score:%5.1f\n",pt->num,pt->score);

    return 0;

}