php - Regular Expressions: How to Express w Without Underscore

Question

Is there a concise way to express:

w but without _

That is, "all characters included in w, except _"

I'm asking this because I'm looking for the most concise way to express domain name validation. A domain name may include lowercase and uppercase letters, numbers, period signs and dashes, but no underscores. w includes all of the above, plus an underscore. So, is there any way to "remove" an underscore from w via regex syntax?

Edited: I'm asking about regex as used in PHP.

Thanks in advance!

Answer 1

the following character class (in Perl)

[^W_]

W is the same as [^w]