谁帮我解释下，这程序文件以存储的时候就报错，我用的是VC 6.0，我想应该是二进制与ASCII之间的
问题，但是我那分不清，谁跟我说一下

#include <stdio.h>
#include <stdlib.h>
#define L sizeof(struct student)
typedef struct student
{
    long num;
    char name[15];
    struct student *next;
}stu;
stu *head,*head1;
int n=0,n1=0;
void creat()
{
    stu *p1,*p2;
    p1=(stu *)malloc(L);
    printf("输入学号:\n");
    scanf("%ld",&p1->num);
    printf("输入姓名:\n");
    scanf("%s",p1->name);
    while(p1->num!=0)
    {
        system("cls");
        n=n+1;
        if(n==1)
            head=p1;
        else
            p2->next=p1;
        p2=p1;
        p1=(stu *)malloc(L);
        printf("再输入学号:\n");
        scanf("%ld",&p1->num);
        printf("输入姓名:\n");
        scanf("%s",p1->name);
    }
    p2->next=NULL;
}
void cunchu( stu *p)
{
    FILE *fp;
    char filename[15];
    system("cls");
    printf("输入存储的文件名:\n");
    scanf("%s",filename);
    if((fp=fopen("filename","wb")==NULL))
    {
        printf("文件打开失败\n");
        exit(0);
    }
    while(p->num!=0)
    {
        fprintf(fp,"%ld,%s",&p->num,p->name);
        p=p->next;
    }
}
void shuchu()
{
    FILE *fp;
    stu *p1,*p2;
    char filename[15];
    system("cls");
    printf("输入所要查询信息所在的文件:\n");
    scanf("%s",filename);
    if((fp=fopen("filename","rb"))==NULL)
    {
        printf("打开失败\n");
        exit(0);
    }
    p1=(stu *)malloc(L);
    fscanf(fp,"%ld,%s",&p1->num,p1->name);
    printf("学号: %ld,姓名: %s",p1->num,p1->name);
    head1=NULL;
    while(!feof(fp))
    {
        n1=n1+1;
        if(n1==1)
            head1=p1;
        else
            p2->next=p1;
        p2=p1;
        p1=(stu *)malloc(L);
        fscanf(fp,"%ld,%s",&p1->num,p1->name);
        printf("\n学号: %ld,姓名: %s",p1->num,p1->name);
    }
}

void main()
{
    creat();
    cunchu(head);
    shuchu();
    system("pause");
}