Hex character to int in C++

Question

How can I change a hex character, not string, into a numerical value?

While typing this question, I found many answers on how to convert hex strings to values. Howe

Answer 1

Something like the following?

//!         \return
//!             The numeric value of ch, if it is hex, otherwise -1
int
fromHexChar( char ch )
{
    static char const hexChars[] = "0123456789ABCDEF";
    char const* p = std::find( begin( hexChars ), end( hexChars ),
                               ::tolower( (unsigned char)ch ) );
    return p == end( hexChars )
        ? -1
        : p - begin( hexChars );
}