Regex: Match everything except string

Question

I've got the regex

^(.)+?domain\.com

which machtes

www.domain.com or
domain.com or
something.domain.com but
.domain.com too.

What I want is to "filter out" the possibility of ".domain.com". It should match [something].domain.com and domain.com but NOT .domain.com. (or ..domain.com). It should be a valid subdomain. What would be the correct regex to get this done?

Updated question to clarify requirements.

Answer 1

这种模式可以做到

^([^.]+\.)*domain\.com

Answer 2

Actually it will match otherdomain.com too. A better approach might be to allow zero or one occurrences of non-dot+ dot:

^([^.]+\.)?domain.com$

As suggested in a comment, to allow many levels of subdomains, change ? to * .

Answer 3

这将允许多个子域和域本身

^(.*\.)?domain.com&