Structure and File Handling

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#define no 2
struct
{
int r_no;
char name[30];
int m1;
}s[no];
void main()
{
int i;
FILE *fp;
clrscr();
fp=fopen("C:\Student.dat","w");
if(fp==NULL)
 {
 printf("File cannot be created!");
 exit(0);
 }
for(i=0;i<no;i++)
 {
 printf("\nData collection for student%d:",i+1);
 printf("\nRoll no: ");
 scanf("%d",&s[i].r_no);
 flushall();
 printf("Name: ");
 gets(s[i].name);
 printf("Mark: ");
 scanf("%d",&s[i].m1);
 }
fwrite(s,sizeof(s),no,fp);
rewind(fp);
printf("\nFailed students' info:\n");
printf("\nRollno Name\t\t\tMarks");
printf("\n------ ----\t\t\t-----");
fread(s,sizeof(s),no,fp);
for(i=0;i<no;i++)
 if(s[i].m1<40)
  printf("\n%-5d  %-25s%-7d",s[i].r_no,s[i].name,s[i].m1);
fclose(fp);
getch();
}