学生籍贯信息管理系统

#include <stdio.h>
#include <malloc.h>
#define LEN sizeof(struct student)
#define NULL 0

struct student
{long num;
char name[20];
char jg[20];
struct student *next;
};

int n=0;

void save(struct student *head)
{ FILE *fp;
char filename[20];
struct student *p1;
printf("Please input the filename\n");
scanf("%s",filename);
if((fp=fopen(filename,"w"))==NULL)
      {printf("can't open file\n");
       return;
      }
for(p1=head;p1!=NULL;p1=p1->next)
      {fprintf(fp,"%ld",p1->num);
       fputc('\t',fp);
       fprintf(fp,"%s",p1->name);
       fputc('\t',fp);
       fputc('\t',fp);

       fprintf(fp,"%s",p1->jg);
       fputc('\n',fp);
      }
free(p1);
fclose(fp);
}

void print(struct student *head)
{ struct student*p;
printf("\nNow,these information is:\n");
p=head;
if(head!=NULL)
do
    {printf("%ld\t%s\t\t%s\n",p->num,p->name,p->jg);
     p=p->next;
    }while(p!=NULL);
}

struct student *creat()
{ struct student *head,*p1,*p2;
char ch;
p1=p2=(struct student *)malloc(LEN);
printf("\n      Welcome to student jiguan system!\n");
printf("Please input one's num,name and jiguan\n");
printf("\"0 0 0\":exit\n");
scanf("%ld%s%s",&p1->num,p1->name,p1->jg);
head=NULL;
while(p1->num!=0)
    {n=n+1;
     if(n==1)head=p1;