IsPrime

import java.util.Scanner;

public class IsPrime
{
    //determine if a given integer is prime
    public static void main(String[] args)
    {
        //declare variables
        Scanner input = new Scanner(System.in);
        int num, i;
        double quotient;
        boolean isPrime = true;

        //take integer
        System.out.print("Enter an integer: ");
        num = input.nextInt();

        /*
         * --test if prime--
         * -iterate through every int in range 1 <= i <= num
         * -divide num by i
         * -if result is a non-integer, number is not prime, break loop
         * -if the loop exits without breaking, number is prime
         */
        for (i = num; i > 0; i--)
        {
            quotient = (double)num / (double)i;
            if (quotient != (int)quotient)
            {
                isPrime = false;
                break;
            }
        }

        //print result
        if (isPrime)
        {
            System.out.printf("%d is prime.\n", num);
        }
        else
        {
            System.out.printf("%d is not prime.\n", num);
        }

        //clean up
        input.close();
    }
}