Convert Plain Text Links to HTML links with regular expressions

Question

I need regular expression that converts links in plain text to HTML links.

Here are the following test links:

http://www.a-domain.com/something/?something
www.a-domain.com/something/?something

The regular expression should also work under the following assumptions:

Anything attached to the URL that isn't a part of the URL (a comma or period, for example) should be ignored. I found this one, but it does not meet all of my needs.

Does anyone have the right regular expression for my needs?

Answer 1

(http://|www\.)([^\s()[\]<>]+|\([^\s)]*\)|\[[^\s\]]*])+(?<![.,!?])

This handles most cases, but does not try to handle all. (It uses a negative lookbehind assertion at the end; I don't know if your C# or asp.net regex libraries can handle that, but it is an easy way to make it "non-greedy" on those characters at the end.)

You haven't been very explicit about your needs or how the linked regex doesn't meet them; more examples of what should and shouldn't be matched, for you, would clarify, but I think this will help.

Answer 2

In this blog post, Regex guru Jan Goyvaerts shows a few ways how to go about matching URLs in plain text. He also shows many common pitfalls.

For your case, I'd recommend

\b(?:(?:https?|ftp|file)://|www\.|ftp\.)[-A-Z0-9+&@#/%=~_|$?!:,.]*[A-Z0-9+&@#/%=~_|$]

(case-insensitive mode turned on)