Byte Array to Hexadecimal String

Lookup

• Text: 23,879.41 (20.8X faster)
• Sentence: 1.15 (23.9X faster)

/// <summary>
/// Hex string lookup table.
/// </summary>
private static readonly string[] HexStringTable = new string[]
{
    "00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "0A", "0B", "0C", "0D", "0E", "0F",
    "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "1A", "1B", "1C", "1D", "1E", "1F",
    "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "2A", "2B", "2C", "2D", "2E", "2F",
    "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "3A", "3B", "3C", "3D", "3E", "3F",
    "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "4A", "4B", "4C", "4D", "4E", "4F",
    "50", "51", "52", "53", "54", "55", "56", "57", "58", "59", "5A", "5B", "5C", "5D", "5E", "5F",
    "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "6A", "6B", "6C", "6D", "6E", "6F",
    "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "7A", "7B", "7C", "7D", "7E", "7F",
    "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "8A", "8B", "8C", "8D", "8E", "8F",
    "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", "9A", "9B", "9C", "9D", "9E", "9F",
    "A0", "A1", "A2", "A3", "A4", "A5", "A6", "A7", "A8", "A9", "AA", "AB", "AC", "AD", "AE", "AF",
    "B0", "B1", "B2", "B3", "B4", "B5", "B6", "B7", "B8", "B9", "BA", "BB", "BC", "BD", "BE", "BF",
    "C0", "C1", "C2", "C3", "C4", "C5", "C6", "C7", "C8", "C9", "CA", "CB", "CC", "CD", "CE", "CF",
    "D0", "D1", "D2", "D3", "D4", "D5", "D6", "D7", "D8", "D9", "DA", "DB", "DC", "DD", "DE", "DF",
    "E0", "E1", "E2", "E3", "E4", "E5", "E6", "E7", "E8", "E9", "EA", "EB", "EC", "ED", "EE", "EF",
    "F0", "F1", "F2", "F3", "F4", "F5", "F6", "F7", "F8", "F9", "FA", "FB", "FC", "FD", "FE", "FF"
};

/// <summary>
/// Returns a hex string representation of an array of bytes.
/// </summary>
/// <param name="value">The array of bytes.</param>
/// <returns>A hex string representation of the array of bytes.</returns>
public static string ToHex(this byte[] value)
{
    StringBuilder stringBuilder = new StringBuilder();
    if (value != null)
    {
        foreach (byte b in value)
        {
            stringBuilder.Append(HexStringTable[b]);
        }
    }

    return stringBuilder.ToString();
}

The above approach runs 25% faster than using a small hex alphabet and doing something like:

• Text: 23,201.23 (21.4X faster)
• Sentence: 1.24 (22.3X faster)

StringBuilder stringBuilder = new StringBuilder();
string hexAlphabet = "0123456789ABCDEF";
if (value != null)
{
    foreach (byte b in value)
    {
        stringBuilder.Append(hexAlphabet[(int)(b >> 4)]);
        stringBuilder.Append(hexAlphabet[(int)(b & 0xF)]);
    }
}

 BitConverter

• Text: 113,269.34 (4.4X faster)
• Sentence: 9.98 (2.8X faster)

public static string ByteArrayToString(byte[] ba)
{
  string hex = BitConverter.ToString(ba);
  return hex.Replace("-","");
}

StringBulider.AppendFormat

• Text: 672,115.77 (1.1X faster)
• Sentence: 36.82 (1.1X faster)

public static string ByteArrayToString(byte[] ba)
{
  StringBuilder hex = new StringBuilder(ba.Length * 2);
  foreach (byte b in ba)
    hex.AppendFormat("{0:x2}", b);
  return hex.ToString();
}

• Text: 718,380.63 (1.0X faster)
• Sentence: 39.71 (1.0X faster)

        static string ByteArrayToHexStringViaStringBuilderAggregateAppendFormat(byte[] bytes)
        {
            return bytes.Aggregate(new StringBuilder(bytes.Length * 2), (sb, b) => sb.AppendFormat("{0:X2}", b)).ToString();
        }

Array.ConvertAll

• Text: 752,078.70 (1.0X faster)
• Sentence: 18.28 (2.2X faster)

        static string ByteArrayToHexStringViaStringConcatArrayConvertAll(byte[] bytes)
        {
            return string.Concat(Array.ConvertAll(bytes, b => b.ToString("X2")));
        }

• Text: 675,451.57 (1.1X faster)
• Sentence: 17.95 (2.2X faster)

        static string ByteArrayToHexStringViaStringJoinArrayConvertAll(byte[] bytes)
        {
            return string.Join(string.Empty, Array.ConvertAll(bytes, b => b.ToString("X2")));
        }

{byte}.ToString("x2")

• Text: 308,805.38 (2.4X faster)
• Sentence: 16.89 (2.4X faster)

        static string ByteArrayToHexStringViaStringBuilderForEachByteToString(byte[] bytes)
        {
            StringBuilder hex = new StringBuilder(bytes.Length * 2);
            foreach (byte b in bytes)
                hex.Append(b.ToString("X2"));
            return hex.ToString();
        }

• Text: 352,828.20 (2.1X faster)
• Sentence: 16.87 (2.4X faster)

        static string ByteArrayToHexStringViaStringBuilderAggregateByteToString(byte[] bytes)
        {
            return bytes.Aggregate(new StringBuilder(bytes.Length * 2), (sb, b) => sb.Append(b.ToString("X2"))).ToString();
        }

{SoapHexBinary}.ToString()

        static string ByteArrayToHexViaSoapHexBinary(byte[] bytes)
        {
            SoapHexBinary soapHexBinary = new SoapHexBinary(bytes);
            return soapHexBinary.ToString();
        }

Byte Manipulation

• Text: 16,856.64 (29.5X faster)
• Sentence: 0.70 (39.5X faster)

        static string ByteArrayToHexViaByteManipulation(byte[] bytes)
        {
            char[] c = new char[bytes.Length * 2];
            byte b;
            for (int i = 0; i < bytes.Length; i++)
            {
                b = ((byte)(bytes[i] >> 4));
                c[i * 2] = (char)(b > 9 ? b + 0x37 : b + 0x30);
                b = ((byte)(bytes[i] & 0xF));
                c[i * 2 + 1] = (char)(b > 9 ? b + 0x37 : b + 0x30);
            }
            return new string(c);
        }

• Text: 12,967.69 (38.4X faster)
• Sentence: 0.73 (37.9X faster)

        static string ByteArrayToHexViaByteManipulation2(byte[] bytes)
        {
            char[] c = new char[bytes.Length * 2];
            int b;
            for (int i = 0; i < bytes.Length; i++)
            {
                b = bytes[i] >> 4;
                c[i * 2] = (char)(55 + b + (((b - 10) >> 31) & -7));
                b = bytes[i] & 0xF;
                c[i * 2 + 1] = (char)(55 + b + (((b - 10) >> 31) & -7));
            }
            return new string(c);
        }

 Lookup by byte

• Text: 10,853.96 (45.8X faster)
• Sentence: 0.65 (42.7X faster)

private static readonly uint[] _lookup32 = CreateLookup32();

private static uint[] CreateLookup32()
{
    var result = new uint[256];
    for (int i = 0; i < 256; i++)
    {
        string s=i.ToString("X2");
        result[i] = ((uint)s[0]) + ((uint)s[1] << 16);
    }
    return result;
}

private static string ByteArrayToHexViaLookup32(byte[] bytes)
{
    var lookup32 = _lookup32;
    var result = new char[bytes.Length * 2];
    for (int i = 0; i < bytes.Length; i++)
    {
        var val = lookup32[bytes[i]];
        result[2*i] = (char)val;
        result[2*i + 1] = (char) (val >> 16);
    }
    return new string(result);
}

Lookup by byte unsafe

private static readonly uint[] _lookup32Unsafe = CreateLookup32Unsafe();
private static readonly uint* _lookup32UnsafeP = (uint*)GCHandle.Alloc(_lookup32Unsafe,GCHandleType.Pinned).AddrOfPinnedObject();

private static uint[] CreateLookup32Unsafe()
{
    var result = new uint[256];
    for (int i = 0; i < 256; i++)
    {
        string s=i.ToString("X2");
        if(BitConverter.IsLittleEndian)
            result[i] = ((uint)s[0]) + ((uint)s[1] << 16);
        else
            result[i] = ((uint)s[1]) + ((uint)s[0] << 16);
    }
    return result;
}

public static string ByteArrayToHexViaLookup32Unsafe(byte[] bytes)
{
    var lookupP = _lookup32UnsafeP;
    var result = new char[bytes.Length * 2];
    fixed(byte* bytesP = bytes)
    fixed (char* resultP = result)
    {
        uint* resultP2 = (uint*)resultP;
        for (int i = 0; i < bytes.Length; i++)
        {
            resultP2[i] = lookupP[bytesP[i]];
        }
    }
    return new string(result);
}

Or if you consider it acceptable to write into the string directly:

public static string ByteArrayToHexViaLookup32UnsafeDirect(byte[] bytes)
{
    var lookupP = _lookup32UnsafeP;
    var result = new string((char)0, bytes.Length * 2);
    fixed (byte* bytesP = bytes)
    fixed (char* resultP = result)
    {
        uint* resultP2 = (uint*)resultP;
        for (int i = 0; i < bytes.Length; i++)
        {
            resultP2[i] = lookupP[bytesP[i]];
        }
    }
    return result;
}

Quote From

How do you convert Byte Array to Hexadecimal String, and vice versa

byte[] to hex string

blambert/codesnip – Fast byte array to hex string conversion