How to convert hex to a byte array?

Consider leveraging a Framework class that already exposes the ability to perform hex conversion, XmlReader for example:

public static byte[] HexToBytes(this string hexEncodedBytes, int start, int end)
{
    int length = end - start;
    const string tagName = "hex";
    string fakeXmlDocument = String.Format("<{1}>{0}</{1}>",
                           hexEncodedBytes.Substring(start, length),
                           tagName);
    var stream = new MemoryStream(Encoding.ASCII.GetBytes(fakeXmlDocument));
    XmlReader reader = XmlReader.Create(stream, new XmlReaderSettings());
    int hexLength = length / 2;
    byte[] result = new byte[hexLength];
    reader.ReadStartElement(tagName);
    reader.ReadContentAsBinHex(result, 0, hexLength);
    return result;
}

usage:

string input = "0xBAC893CAB8B7FE03C927417A2A3F6A60BD30FF35E250011CB255";
byte[] bytes = input.HexToBytes(2, input.Length);

Something like this:

    public byte[] ParseHexString(string text)
    {
        if ((text.Length % 2) != 0)
        {
            throw new ArgumentException("Invalid length: " + text.Length);
        }

        if (text.StartsWith("0x", StringComparison.InvariantCultureIgnoreCase))
        {
            text = text.Substring(2);
        }

        int arrayLength = text.Length / 2;
        byte[] byteArray = new byte[arrayLength];
        for (int i = 0; i < arrayLength; i++)
        {
            byteArray[i] = byte.Parse(text.Substring(i*2, 2), NumberStyles.HexNumber);
        }

        return byteArray;
    }