Question

I need to match the “base” url, what I mean is:

Not match --> http://google.com
Not match --> http://www.google.com
Not match --> www.google.com
Match! --> google.com

I was trying to use a negative look behind to make sure there was no http:// or www, but it didn’t seem to work correctly.

Answer 1

Do this has to be with only one regex?

You could have the first regex that will match all URLs found. Something like that:

\b.+?\.\w{2,4}\b

And then filter all matches and keep the ones that do not match the following:

^(http://|www)

although to be honest, I wouldn’t use Regex unless it is strictly necessary for that.

Note:
You can always find a better regex to match the URLs. The thing here is that they may not start with http:// or www, so we can’t restrict the regex so much. Be ready to have other matches that are not urls at all, like:

yesterday.but in I was there yesterday.but no one saw me