Prime Numbers Between two Intervals using Function

#include<stdio.h>

#include<conio.h>

int check_prime(int num);

void main(){

   int n1,n2,i,flag;

   printf("Enter two numbers(intervals): ");

   scanf("%d %d",&n1, &n2);

   printf("Prime numbers between %d and %d are: ", n1, n2);

   for(i=n1+1;i<n2;++i)

   {

      flag=check_prime(i);

      if(flag==0)

         printf("%d ",i);

   }

   getch();

}

int check_prime(int num) /* User-defined function to check prime number*/

{

   int j,flag=0;

   for(j=2;j<=num/2;++j){

        if(num%j==0){

            flag=1;

            break;

        }

   }

   return flag;

}