Published 2022-02-24
Prime Number
All programmers came across this program once in their life. Even I also did but I wonder why nobody thought of this. In the prime number everyone creates a loop till the number < number - 1. This is correct but you can write it more efficiently. If you check till number < (number/2) is enough. Don't you think? It's a simple mathematics, a number > (number/2) will never be the multiple of that number.
import java.util.Scanner;
public class PrimeNumber {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("Enter a number: ");
int number = in.nextInt();
in.close();
boolean isPrime = true;
int loopVar = number / 2;
for (int x = 2; x < loopVar; x++) {
if (number % x == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
System.out.println("The number " + number + " is a prime number.");
} else {
System.out.println("The number " + number + " is a NOT prime number.");
}
}
}