Convert a single hex character to its byte value in C#

Question

This will convert 1 hex character to its integer value, but needs to construct a (sub) string.

Convert.ToInt32(serializedString.Substring(0,1), 16);

Does .NET have a built-in way to convert a single hex character to its byte (or int, doesn't matter) value that doesn't involve creating a new string?

Answer 1

int value = "0123456789ABCDEF".IndexOf(char.ToUpper(sourceString[index]));

Or even faster (subtraction vs. array search), but no checking for bad input:

int HexToInt(char hexChar)
{
    hexChar = char.ToUpper(hexChar);  // may not be necessary

    return (int)hexChar < (int)'A' ?
        ((int)hexChar - (int)'0') :
        10 + ((int)hexChar - (int)'A');
}

Answer 2

Correct me if im wrong but can you simply use

Convert.ToByte(stringValue, 16);

as long as the stringValue represents a hex number? Isnt that the point of the base paramter?

Strings are immutable, I dont think there is a way to get the substring byte value of the char at index 0 without creating a new string