I hope you were joking when you asked what the error was !!
Your code had bunch of errors ,which could be corrected if you write the code in small chunks.
From what i can tell, you just opened you fav notepad app & wrote what you think would have worked .anyways i have corrected the code which compiles but not sure what logic it uses .
Cheers !!
#include <stdio.h>
struct bank
{
int acc_no;
char acc_name[10];
float balence;
int pin;
char acc_type[10];
}s1[3];
int main(){
int i;
printf(" enter bank Customer record ");
for(i=0; i<3; i++)
{
scanf("%d %s %f %d %s", &(s1[i].acc_no), s1[i].acc_name, &(s1[i].balence), &(s1[i].pin), s1[i].acc_type );
}
for(i=0;i<3;i++);
{
if(s1[i].balence>1000000)
printf("%s is golden customer", s1[i].acc_name);
else if(s1[i].balence>500000 && s1[i].balence<100000){
printf("%s is silver customer", s1[i].acc_name);
}
else if(s1[i].balence<99999)
printf("%s is general customer", s1[i].acc_name);
}
return 0;
}