using System;

using System.Security.Cryptography;

using System.Text;

using System.IO;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var hexBytes = HexToByteArray("000ac94439020000e6ca");

        var textBytes = System.Text.Encoding.UTF8.GetBytes("test");

        var hexBytes2 = System.Text.Encoding.BigEndianUnicode.GetBytes(System.Text.Encoding.BigEndianUnicode.GetString(hexBytes));

        Console.WriteLine("000ac94439020000e6ca");

        Console.WriteLine(ByteArrayToHex(hexBytes2));

        byte test = 128;

        Console.WriteLine(Convert.ToInt32(test));

    }

    public static byte[] HexToByteArray(string hex)

    {

        var bytes = Enumerable.Range(0, hex.Length)

            .Where(x => x % 2 == 0)

            .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))

            .ToArray();

        return bytes;

    }

    public static string HextoString(string hex)

    {

​

        byte[] bytes = Enumerable.Range(0, hex.Length)

                         .Where(x => x % 2 == 0)

                         .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))

                         .ToArray();

        return System.Text.Encoding.UTF8.GetString(bytes);

    }

    public static string ByteArrayToHex(byte[] bytes)

    {

      return BitConverter.ToString(bytes).Replace("-","");

    }

    public static bool IsHex(string s)

    {

      // Iterate over string

      for (int i = 0; i < s.Length; i++)

      {

        char ch = s[i];

        if ((ch < '0' || ch > '9') &&

            (ch < 'A' || ch > 'F'))

        {

          return false;

        }

      }

      return true;

    }

}