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ASP.NET/VB/REGEX:  Make .com Domains Clickable Links

Posted on 2013-11-18
Last Modified: 2013-11-21

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should become this:
<a target="_blank" href="http://example.com">example.com</a>
<a target="_blank" href="http://xyz.example.com">xyz.example.com</a>
<a target="_blank" href="http://abc.xyz.example.com">abc.xyz.example.com</a>
<a target="_blank" href="http://www.experts-exchange.com">www.experts-exchange.com</a>

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This only works if it starts with www:
'input = RegularExpressions.Regex.Replace(input, "(?<!\S)(\www\.\S+[^\s@,.""']+)", "<a href=""http://$1"">$1</a>")

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Question by:hankknight
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LVL 30

Expert Comment

by:Alexandre Simões
ID: 39659248
The problem here is that you're removing some insurance to the matches.
Basically you want to match an url that doesn't begin neither by http:// or www

There's no clear safe way of doing this as there are plenty of way to make these matches fail.

I could make one that searches by domain: .com, .net, .whatever...
Basically matching whole lines that end with . something.
But imagine you have an url like:
and a norlam text line like:
I am going there. And there.
They would both match!

So, my final assumption is that:
- the url must not have spaces
- must contain at least one dot before the end

This said try this:

Although we can still break it...
LVL 16

Author Comment

ID: 39659253
This only needs to apply to .com domain names.
LVL 30

Expert Comment

by:Alexandre Simões
ID: 39659318
ok, if it's only .com domain names and nothing else after you could use this:

With this you can also have the domains anywhere in the file.
LVL 16

Author Comment

ID: 39659456
How can I get that to work with my ASP.NET/VB code like this?
'input = RegularExpressions.Regex.Replace(input, "(?<!\S)(\www\.\S+[^\s@,.""']+)", "<a href=""http://$1"">$1</a>")

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LVL 30

Accepted Solution

Alexandre Simões earned 500 total points
ID: 39659479
Something like this:
Dim strRegex as String = "[A-z0-9][\w\._-]+.com"
Dim myRegexOptions As RegexOptions = RegexOptions.None
Dim myRegex As New Regex(strRegex, myRegexOptions)
Dim strTargetString As String = "!! Your text here !!"
Dim strReplace As String = "<a href=""http://$&"">$1</a>"

Dim result as String = myRegex.Replace(strTargetString, strReplace)

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