Regex for finding domains in a sentence but not IP addresses

Question

I am trying to write a regular expression that will match domains in a sentence.

I found this post which was very useful and helped me create the following to match domains, but it also unfortunately matches IP addresses too which I do not want:

((?!-))(xn--)?[a-z0-9][a-z0-9-_]{0,61}[a-z0-9]{0,1}\.(xn--)?([a-z0-9\._-]{1,61}|[a-z0-9-]{1,30})

I want to update my expression so that the following can still be found: in a sentence, between brackets, etc.:

www.example.com
subdomain.example.com
subdomain.example.co.uk

But not:

192.168.0.0
127.0.0.1

Is there a way to do this?

You may match IPs and match and capture everything else using your regex. Something like `\d{1,3}(?:\.\d{1,3}){3}|(your_regex)` and grab Group 1 values. — Wiktor Stribiżew, Apr 15 '19 at 14:09
@WiktorStribiżew Thanks for the suggestion but that still selects IP addresses unfortunately. — Twiggy, Apr 16 '19 at 08:31
Yes, but you do not have to *keep* them, as you only need to grab Group 1 values. — Wiktor Stribiżew, Apr 16 '19 at 08:31

score 2 · Accepted Answer · answered Apr 15 '19 at 17:05

2

We could use a simple lookahead that excludes combinations of numbers and dots only: (?![\d.]+)

(?![\d.]+)((?!-))(xn--)?[a-z0-9][a-z0-9-_]{0,61}[a-z0-9]{0,1}\.(xn--)?([a-z0-9\._-]{1,61}|[a-z0-9-]{1,30})

Demo

answered Apr 15 '19 at 17:05

wp78de

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Sahil · Answer 2 · 2020-11-10T17:22:30.410

1

Answer from @wp78de is correct, however it would not detect the domains starting with Numerical digits i.e. 123reg.com

So remove the first group in the regex like this

((?!-))(xn--)?[a-z0-9][a-z0-9-_]{0,61}[a-z0-9]{0,1}\.(xn--)?([a-z0-9\._-]{1,61}|[a-z0-9-]{1,30})

edited Nov 10 '20 at 17:22

answered Apr 18 '19 at 08:30

Sahil

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Regex for finding domains in a sentence but not IP addresses

2 Answers2