regex - How can I exclude some characters from a class?

Question

Say I want to match a "word" character (w), but exclude "_", or match a whitespace character (s), but exclude "". How can I do this?

Answer 1

Use a negated class including W or S.

/[^W_]/  # anything that's not a non-word character and not _
/[^S]/ # anything that's not a non-space character and not