How does this While loop exit ? (java)

Question

I tried to figure out how this program works, and I got stuck at While loop, I don't understand how the second loop exit, since the v will never end up equal to 0 or negative. Since it's the only conditions that would exit that loop, or am I missing something deeper? The code converts integers (>0) into binary.

public class Binary { 
public static void main(String[] args) { 

    // read in the command-line argument
    int n = Integer.parseInt(args[0]);

    // set v to the largest power of two that is <= n
    int v = 1;
    while (v <= n/2) {
        v = v * 2;
    }

    // check for presence of powers of 2 in n, from largest to smallest
    while (v > 0) {

        // v is not present in n 
        if (n < v) {
            System.out.print(0);
        }

        // v is present in n, so remove v from n
        else {
            System.out.print(1);
            n = n - v;
        }

        // next smallest power of 2
        v = v / 2;
    }

    System.out.println();

}

}

Answer 1

v is an int, and in Java 1/2 as an int gives 0. Your loop goes through all the powers of two so will reach one, and then 0.

Run it in a debugger to see!

Answer 2

Think to start with

n=10

so

v=8

the system will print

1010

and the iterations are:

1 - 10>8 else statement so print 1 and: n=2, v=4

2 - 2<4 if statement so print 0 and: v=2

3 - 2=2 else statement so print 1 and: n=0, v=1

4 - 0<1 if statement so print 0 and: n=0, v=1/2 that is 0 as integer

During the next iteration while condition it is not satisfied anymore and the code ends.

Answer 3

I feel that you have a problem in understanding the Integer Division . In integer division, 3/2 does not equal to 1.5 but instead it is 1 . So similarly 1/2 is not equal to 0.5 but instead it is 0 . Since variable v is integer the division by integer 2 is always integer division. So your variable v will ultimately reach 0 .