Most light weight conversion from hex to byte in c#? [duplicate]

Answer 1

As a variant of Jon's if based ParseNybble:

public static byte[] ParseHex(string hexString)
{
    if ((hexString.Length & 1) != 0)
    {
        throw new ArgumentException("Input must have even number of characters");
    }
    byte[] ret = new byte[hexString.Length / 2];
    for (int i = 0; i < ret.Length; i++)
    {
        int high = ParseNybble(hexString[i*2]);
        int low = ParseNybble(hexString[i*2+1]);
        ret[i] = (byte) ((high << 4) | low);
    }

    return ret;
}

private static int ParseNybble(char c)
{
    unchecked
    {
        uint i = (uint)(c - '0');
        if(i < 10)
            return (int)i;
        i = ((uint)c & ~0x20u) - 'A';
        if(i < 6)
            return (int)i+10;
        throw new ArgumentException("Invalid nybble: " + c);
    }
}