//IterativeDemo.java

import java.util.Scanner;

public class IterativeDemo
{
    public static void main(String[] args)
    {
        System.out.println("Enter an integer:");
        Scanner keyboard = new Scanner(System.in);
        int number = keyboard.nextInt();
        System.out.println("The digits in that number are:");
        displayAsWords(number);
        System.out.println();

        System.out.println("If you add ten to that number, ");
        System.out.println("the digits in the new number are:");
        number = number + 10;
        displayAsWords(number);
        System.out.println();
    }

    /**
     * Precondition: number >= 0.
     * Displays the digits in number as words.
     */
    public static void displayAsWords
    (
        int number
    )
    {
        int divisor = getPowerOfTen(number);
        int next = number;
        while (divisor >= 10)
        {
            System.out.print(getWordFromDigit(next / divisor) + " ");
            next = next % divisor;
            divisor = divisor / 10;
        }
        System.out.print(getWordFromDigit(next / divisor) + " ");
    }

    //Precondition: n >= 0. 
    //Returns 10 raised to the power n.
    private static int getPowerOfTen(int n)
    {
        int result = 1;
        while (n >= 10)
        {
            result = result * 10;
            n = n / 10;
        }
        return result;
    }

    //Precondition: 0 <= digit <= 9
    //Returns the word for the argument digit.
    private static String getWordFromDigit(int digit)
    {
        String result = null;
        switch (digit)
        {
        case 0:
            result = "zero";
            break;
        case 1:
            result = "one";
            break;
        case 2:
            result = "two";
            break;
        case 3:
            result = "three";
            break;
        case 4:
            result = "four";
            break;
        case 5:
            result = "five";
            break;
        case 6:
            result = "six";
            break;
        case 7:
            result = "seven";
            break;
        case 8:
            result = "eight";
            break;
        case 9:
            result = "nine";
            break;
        default:
            System.out.println("Fatal Error.");
            System.exit(0);
            break;
        }
        return result;
    }
}