changing the line using fseek in c

#include<stdio.h>
void main()
  {
    FILE *f;
    char uname[20],pass[20],name1[]={"b"},pass1[]={"2"};
    int s=0,i=0;
    f=fopen("users.dat","r+");
    clrscr();
    do
    {
     s=(4*i);
     i++;
     fseek(f,s,SEEK_SET);
     fscanf(f,"%s %s",uname,pass);
     printf("\n%s %s",uname,pass);
     printf("\tcur pos : %ld",ftell(f));
     fflush(f);
    }while(!feof(f));
    getch();
  }