hostname regex help

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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?

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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\.]+)

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

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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