The input: we get some plain text as input string and we have to highlighight all URLs there with <a href={url}>{url></a>.
For some time I've used regex taken from http://flanders.co.nz/2009/11/08/a-good-url-regular-expression-repost/, which I modified several times, but it's built for another issue - to check whether the whole input string is an URL or no.
So, what regex do you use in such issues?
UPD: it would be nice if answers were related to php :-[
Take a look at a couple of modules available on CPAN:
where the latter is a little more forgiving. The regular expressions are available in the source code (the latter's, for example).
For example:
#! /usr/bin/perl
use warnings;
use strict;
use URI::Find::Schemeless;
my $text = "http://stackoverflow.com/users/251311/zerkms is swell!\n";
URI::Find::Schemeless
->new(sub { qq[<a href="$_[0]">$_[0]</a>] })
->find(\$text);
print $text;
Output:
<a href="http://stackoverflow.com/users/251311/zerkms">http://stackoverflow.com/users/251311/zerkms</a> is swell!
For Perl, I usually use one of the modules defining common regex, Regexp::Common::URI::*. You might find a good regexp for you in the sources of those modules.
http://search.cpan.org/search?query=Regexp%3A%3ACommon%3A%3AURI&mode=module
