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Java

Posted by Steven Bell
Steven Bell
660 Points

Four-Digit Integer

Write a program that reads a four-digit integer, such as 1998, and then displays it, one digit per line, like so: 1 9 9 8 Your prompt should tell the user to enter a four-digit integer. You can then assume that the user follows directions. (Hint: Use the division and remainder operators.)

Steven Bell
Steven Bell
660 Points

I'm sorry! It should print out like: 1 9 9 8

Steven Bell
Steven Bell
660 Points

1 /n, 9/n, 9/n, 8/n

1 Answer

Kourosh Raeen
Kourosh Raeen
23,733 Points
Kourosh Raeen
Kourosh Raeen
23,733 Points

Hi Steven - Using the modulus or remainder operator you can get the right-most digit. For example, 1998%10 will give you 8. Then if you divide 1998 by 10 you will get 199 and now you can apply the modulus operator again to get 9. Using this approach you will get the digits, but in reverse order. One thing you could do to print them in the right order is to put digits in a stack and then when you pop them off the stack you'll get them in the right order. Here's the code:

import java.util.Scanner;
import java.util.LinkedList;

public class PrintDigitsStack {

    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        System.out.print("Enter a four digit number: ");
        int num = reader.nextInt();

        LinkedList<Integer> stack = new LinkedList<Integer>();

        while (num > 0) {
            stack.push(num%10);
            num /= 10;
        }

        while (!stack.isEmpty()) {
            System.out.println(stack.pop());
        }
    }
}

I also saw another way of doing this using recursion which eliminates the need for the stack. Here's the code for that:

import java.util.Scanner;

public class PrintDigitsRecursive {

    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        System.out.print("Enter a four digit number: ");
        int num = reader.nextInt();

        printDigits(num);
    }

    public static void printDigits(int num) {
        if(num / 10 > 0) {
            printDigits(num / 10);
        }
        System.out.println(num % 10);
    }
}