Binary Palindrome check in C#

Hi Community,

This post is about how to check whether the binary representation of a byte is a palindrome. I’ve recently received an email by a fellow developer requesting some help with this, and after having done a bit of research I couldn’t find any good example written in C#, so I decided to do it and share it with you. Similar to any other programming task and faithful to the phrase “There’s more than a way to skin a cat”, there are at least a couple of ways to do this via:

 

 

For the sake of clarity and completeness, I have written a code snippet to demonstrate both approaches, and they were implemented as extension methods for byte type as shown below

 

public static class Binary {

    /// <summary>

    /// Gets the bits.

    /// </summary>

    /// <param name="a">a.</param>

    /// <returns></returns>

    public static string GetBits(this byte a) {

        var retval = string.Empty;

 

        if (a > 0) {

            var buffer = new StringBuilder();

            var bitArray = new BitArray(new[] { a });

 

            for (var index = bitArray.Count - 1; index >= 0; index--)

                buffer.Append(bitArray[index] ? "1" : "0");

 

            retval = buffer.ToString().Substring(buffer.ToString().IndexOf("1", StringComparison.OrdinalIgnoreCase));

 

        }

 

        return retval;

    }

 

 

    /// <summary>

    /// Determines whether [is palindrome with string op].

    /// </summary>

    /// <param name="a">a.</param>

    /// <returns></returns>

    public static bool IsPalindromeWithStringOp(this byte a) {

        var retval = false;

        var bitStr = GetBits(a);

 

        if (!string.IsNullOrEmpty(bitStr)) {

            var reversed = new string(bitStr.Reverse().ToArray());

            retval = reversed == bitStr;

        }

 

        return retval;

    }

 

    /// <summary>

    /// Determines whether [is palindrome with bit ops].

    /// </summary>

    /// <param name="a">a.</param>

    /// <returns></returns>

    public static bool IsPalindromeWithBitOps(this byte a) {

        var retval = false;

 

        if (a > 0) {

            var leftShift = 0;

            var tempValue = (int)a;

 

            while (tempValue != 0) {

                leftShift = leftShift << 1;

                var bitCheck = tempValue & 1;

                tempValue = tempValue >> 1;

                leftShift = leftShift | bitCheck;

            }

            retval = (leftShift ^ a) == 0;

        }

 

        return retval;

    }

 

Both methods are invoked 

var values = new byte[] { 9, 98, 17 };

 

Array.ForEach(values, b => Console.WriteLine($"Number {b} has the following bits {b.GetBits()} - IsPalindromeWithStringOp:{b.IsPalindromeWithStringOp()} |IsPalindromeWithBitOps:{b.IsPalindromeWithBitOps()} "));

 

Console.ReadLine();

 

to check they return the same expected result

image

 

Regards,

 

Angel

Leave a Reply

Your email address will not be published. Required fields are marked *

Filed under: Microsoft - @ March 22, 2016 12:44 pm

Tags: , ,