Three Loops for Novice Programmers

2/12/2022
2-minute read

Do you know how these three loops work? Take your time and think about the output of them. ^ ^

Three Loops

public class Loops {
    public void forLoop() {
        int i = 0;
        for (; i < 3; i++) {
            System.out.println("Inside of the for loop: i = " + i);
        }
        System.out.println("Outside of the for loop: i = " + i);
    }

    public void whileLoop1() {
        int i = 0;
        while (i++ <= 1) {
            System.out.println("Inside of the while loop1: i = " + i);
        }
        System.out.println("Outside of the while loop1: i = " + i);
    }

    public void whileLoop2() {
        int i = 0;
        while (++i <= 1) {
            System.out.println("Inside of the while loop2: i = " + i);
        }
        System.out.println("Outside of the while loop2: i = " + i);
    }

    public static void main(String[] args) {
        Loops loops = new Loops();
        loops.forLoop();
        System.out.println();

        loops.whileLoop1();
        System.out.println();

        loops.whileLoop2();
    }
}

Output

Inside of the for loop: i = 0
Inside of the for loop: i = 1
Inside of the for loop: i = 2
Outside of the for loop: i = 3

Inside of the while loop1: i = 1
Inside of the while loop1: i = 2
Outside of the while loop1: i = 3

Inside of the while loop2: i = 1
Outside of the while loop2: i = 2

They’re pretty intuitive, aren’t they?

Observation