Matching a hash character (#) with a regex

Question

I have an XML document that contains a regular expression (so you don't need to escape with \). Basically I'm trying to match musical chord symbols, and this regex works fine, but refuses to match a hash:

\b[A-G](m|b|\#|sus|\d)*?\b

Answer 1

The problem is that \b, the word boundary anchor, only matches between alphanumeric and non-alphanumeric characters, so it won't match after a # (unless that is itself followed by an alphanumeric).

Use

\b[A-G](?:m|b|#|sus|\d)*(?:\b|(?<=#))

No need to escape the #, either.

EDIT: Changed the regex to better reproduce the intended functionality (as I think it should be)

Currently, you're not matching some chords, though; how about

\b[A-G](?:add|maj|j|m|-|b|#|sus|\d|°)*(?:\b|(?<=[#°-]))

That way, you can match all of these:

A7
Abm7 
A#m7sus4
A7b9#13
Amaj7#11
A#°
Abj7add13

I guess there is still room for improvement, though.