C Program to Check a Number is Prime or Not

Program :-

#include <stdio.h>
main(){
    int i, num ,flag = 0;
    printf("enter the number : ");
    scanf("%d",&num);
    for(i = 2 ; i <= num /2 ; i++)
    {
        if(n % i == 0){
            flag = 1;
            break;
        }
     }
     if ( flag == 1)
         printf("\n number is not prime");
     else
         printf("\n number is prime");
 }

Output:-

enter the number
4

number is is not prime