Integer Palindromes

File this one under "Silly, Simple Code Snippet Of The Day"™...

Several times on various programming forums, I've seen question about how to find out if an integer value is a palindrome or not (the number is the same "forwards" and "backwards"; e.g., 71317 would be a palindrome, while 71316 would not). Most of the suggested solutions revolve around converting the integer value to a string and reversing the characters. This makes sense, given that "71317" is just a character representation of a number, and many language APIs have ready-made facilities for reversing strings of characters (or at least arrays). That said, finding out if a number is a palindrome using basic math is dead simple, too. Here's a base-10 example in C#:

    using System.Diagnostics;

    class ScratchUtils
    {
        public static int Reverse(int i)
        {
            int result = 0;
            while (i != 0)
            {
                result = (result * 10) + (i % 10);
                i /= 10;
            }
            return result;
        }

        public static bool IsPalindrome(int i)
        {
            return i == Reverse(i);
        }

        public static void Main()
        {
            Debug.Assert(  0 == Reverse(0));
            Debug.Assert(  1 == Reverse(1));
            Debug.Assert( 21 == Reverse(12));
            Debug.Assert(-21 == Reverse(-12));

            Debug.Assert(IsPalindrome(1));
            Debug.Assert(IsPalindrome(11));
            Debug.Assert(!IsPalindrome(12));
            Debug.Assert(IsPalindrome(121));
        }
    }