/****************************************************************************** * Compilation: javac DigitReverser.java * Execution: java DigitReverser n * * Reverses the digits of a positive integer n using arithmetic. Then, * reverse it again using string concatenation. * * % java DigitReverser 123456789 * 987654321 * 123456789 * ******************************************************************************/ public class DigitReverser { public static void main(String[] args) { int n = Integer.parseInt(args[0]); // original integer // reverse using arithmetic int m = 0; while (n != 0) { m = (10 * m) + (n % 10); n = n / 10; } System.out.println(m); // reverse again using string concatenation String s = ""; while (m != 0) { int digit = m % 10; s = s + digit; m = m / 10; } System.out.println(s); } }