Display Prime Numbers Between Two Intervals

Display Prime Numbers Between two Intervals

public class Prime {

    public static void main(String[] args) {

        int low = 20, high = 50;

        while (low < high) {
            boolean flag = false;

            for(int i = 2; i <= low/2; ++i) {
                // condition for nonprime number
                if(low % i == 0) {
                    flag = true;
                    break;
                }
            }

            if (!flag && low != 0 && low != 1)
                System.out.print(low + " ");

            ++low;
        }
    }
}

Output

23 29 31 37 41 43 47 

In this program, each number between low and high are tested for prime. The inner for loop checks whether the number is prime or not.

The difference between checking a single prime number compared to an interval is, you need to reset the value of flag = false on each iteration of the while loop.

Note: If you check the interval from 0 to 10. Then, you need to exclude 0 and 1. As 0 and 1 are not prime numbers. The condition will be:

if (!flag && low != 0 && low != 1)