Prime Number In C program

//To check prime number see the code in c program.

#include <stdio.h>
int main()
{
    int n, i, flag = 0;

    printf("Enter a positive integer: ");
    scanf("%d",&n);

    for(i=2; i<=n/2; ++i)
    {
        // condition for non-prime number
        if(n%i==0)
        {
            flag=1;
            break;
        }
    }

    if (flag==0)
        printf("%d is a prime number.",n);
    else
        printf("%d is not a prime number.",n);

    return 0;
}

Output:

Here in the output is showing 19 in a prime number.So, we can see the code is works perfectly.