Though the sample question is in C#, it applies to almost any language and framework: for relatively simple checks like IsHex(), you can go the RegEx way, or the compound if-statement way.
Which kind of function do you like most?
I’m not only interested in the percentages, so let me know in the comments why.
–jeroen
PS: if you want to use RegEx in .NET, you can compile them to IL, but be very cautious for the compilation overhead.
The Wiert Corner - irregular stream of stuff 