Question

I’m trying to create a program that will return a certain number decomposed to powers of two. For example 45 would be shown as “2^5 + 2^3 + 2^2 + 2^0”, to do so I converted the number to base 2 and converted it to a string so I could find the index and get the result i wanted. But when trying to return the index all i get is the first index found. Can anyone help me with this part?

import java.util.*;


public class prog{

    public static void main(String[] args){

        Scanner keyb = new Scanner(System.in);
        int val;
        System.out.println("Valor");
        val = keyb.nextInt();
        int aux = val;

        while (aux > 0 ){

            int num = aux % 2;
            aux /= 2;
            String dig = String.valueOf(num);
            String find = "1";
            int index = dig.indexOf(find);

            while (index >= 0) {
                System.out.println(index);
                index = dig.indexOf(find, index + 1);
            }
        }
    }

Answer 1

Your string dig contains either “0” or “1”.

String dig = String.valueOf(num);

You want this instead:

 int power = 0;
 while (aux > 0 ) {
      int num = aux % 2;
      if (num == 1) {
         // Print next term
      }
      power++;
      aux /= 2;
 }

Note also that this algorithm will print the terms in reverse order compared to your specification.