帮忙~c程序找错

return_book()

{

FILE *fp,*fp2;

int i,n;int cardnum;char lendbook[10];

printf("pls input your card no\n"); scanf("%d",&cardnum);

fp=fopen("card.txt","r");

for(i=0;fread(&card[i],sizeof(struct card),1,fp)!=0;i++)

{

if(card[i].cardnum==cardnum)

{

n=i;

fclose(fp);

printf("pls input the book name you want to return\n");

scanf("%s",lendbook);

fp=fopen("students.txt","r");

for(i=0;fread(&student[i],sizeof(struct student),1,fp)!=0;i++)

{

if(strcmp(student[i].lendbook,lendbook)==0)

{

fclose(fp);

fp=fopen("students.txt","r");

fp2=fopen("bookl.txt","w");

for(i=0;fread(&student[i],sizeof(struct student),1,fp)!=0;i++)

{

if(strcmp(student[i].lendbook,lendbook)==0)

{continue; }

fwrite(&student[i],sizeof(struct student),1,fp2);

}

fclose(fp);

fclose(fp2);

fp=fopen("students.txt","w");

fp2=fopen("bookl.txt","r");

for(i=0;fread(&student[i],sizeof(struct student),1,fp2)!=0;i++)

fwrite(&student[i],sizeof(struct student),1,fp);