1 reply to this topic

[atoivan]

can any one help me rewirte dis code and make it recursive .

import java.util.Scanner;

public class Main {

    /**
     * @param args
     *            the command line arguments
     */
    public static void main(String[] args) {
        int total = 0, num = 0;
        int i = 0;
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a number");
        num = in.nextInt();
        for (; i <= num; i++) {
            total += num % 10;
            num /= 10;
        }
        System.out.println(total);
    }

}

Edited by Alexander, 23 November 2010 - 02:47 PM.
[code][/code] tags

[wim DC]

Fairly simple, the condition of the current loop will go into a normal if

if(i<=num){

  //continue

} else {

  //done

} 

The done-path must return a simple value, and the continue-path must calculated the value with the given paramters and call itself again AND return whatever it gives as reply.

private int recurse(){

  if(i<=num){

    return thevalueIcalculatedHere_with_num + recurse(); 

  } else {

    return ?

  } 

}

The simple value it must return is the vallue that gets added in the end, when i>num. In this case we don't want to add anything else so we'll take 0 here.
Now determine the variables and give them as paramter to the function. When calling yourself again, the variables gets updated!
The end result looks like:

private int recurse(int i, int num){

  if(i<=num){

    return num % 10 + recurse(i+1,  num/10);

  } else {

    return 0;

  } 

}