Replace specific part of a string...

I'm trying to find a way to, on a string that could be like this:

Use a function on only the http://www.google.com part, and not the rest. E.G.:
Use rot13 on it so that it ends up like this:

Anyone have any ideas?

Thanks in advance.

 

Try...

print preg_replace("/http:\/\/.*\.com/", $rot13, $string);

PHP:

Or something like that... it's late check the regex