hostname regex help

Question

I have this hostname regex that I'd like to expand on a bit. It will match hostnames such as:

yahoo.com

mail.yahoo.com

but will also match

&^%yahoo.com etc...

(\w+\.\w+\.\w+)

Can someone tell me what I need to add to only allow letters, numbers and periods?

possible duplicate of [The Hostname Regex](http://stackoverflow.com/questions/1418423/the-hostname-regex) — hsz, Apr 29 '11 at 12:32
`[a-zA-Z0-9]` or `[\d\w]` will match those. So, something like `[\d\w.]+\.[\d\w]+\.?[\d\w]*` — Ethan, Apr 29 '11 at 12:34

score 0 · Answer 1 · edited May 23 '17 at 12:29

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Maybe if you tried Google. Regular expression to match DNS hostname or IP Address?

edited May 23 '17 at 12:29

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answered Apr 29 '11 at 12:31

tangrs

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score 0 · Accepted Answer · answered Apr 29 '11 at 12:32

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Try using [a-zA-Z0-9\.]+ instead of \w+.

So all in all this will be:

([a-zA-Z0-9\.]+\.[a-zA-Z0-9\.]+\.[a-zA-Z0-9\.]+)

answered Apr 29 '11 at 12:32

Dennis Röttger

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Thanks Dennis, that works. I'll credit you when the wait period ends. – jim Apr 29 '11 at 12:36
@jim, why do you want to match something like "............." ? Maybe you want to use a online test tool like this here: [http://www.rubular.com/r/4AQ9ASZJpc](http://www.rubular.com/r/4AQ9ASZJpc) – stema Apr 29 '11 at 12:42

score 0 · Answer 3 · edited May 23 '17 at 12:29

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\w should not match &^%. I think you are missing anchors.

Try \b, that matches a word boundary.

\b\w+\.\w+\.\w+\b

But hopefully you are aware that this regex is very simplified? There has been already some question and answers to that topic, e.g. 1141848/regex-to-match-url

edited May 23 '17 at 12:29

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answered Apr 29 '11 at 12:35

stema

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Thanks stema. I didn't have the anchors as you suggested. I'll give this a try now – jim Apr 29 '11 at 12:39

hostname regex help

3 Answers3