c file handling program example

/*this program adds two numbers
and save it into a file named sum_rslt.txt*/

#include< stdio.h>
#include< stdlib.h>
void main()
{
 FILE *f;
 char an='Y';
 struct d
 {
  int a,b,c;
 };
 struct d e;

 f=fopen("sum_rslt.txt","a+");


 while(an=='Y')
 {
  printf("enter first no : ");
  scanf("%d",&e.a);
  fprintf(f,"\nfirst no : %d",e.a);

  printf("\nenter second no : ");
  scanf("%d",&e.b);
  fprintf(f,"\nsecond no : %d",e.b);

  e.c=(e.a+e.b);

  fprintf(f,"\nreslt : %d\n\n\n",e.c);

  printf("\n\npress Y to do again : ");
  fflush(stdin);
  an=getche();
  printf("\n\n");
 }
 fclose(f);
}