changing text to link

Hi how do i change a uesr input like

check out:
www.example.com

into a link and still keep all the texts unchanged?

 

You must use regular expressions. Google for it or wait till someone get sit.

 

<?php
function replace_urls_with_links( $text )
{
	return preg_replace(
		'~(https?://.[^\s]+)~',
		'<a href="$1" target="_blank">$1</a>',
		$text
	);
}

$document =<<< EOD
	My document starts with normal text,
	I go on to post a link to http://interviolet.com
	I then explain that this is my home page, not like 
	http://google.com which is a search engine.
	There are many websites on earth and my aim in life is
	to take over them all ... starting with http://thefirstsite.com
EOD;

echo replace_urls_with_links( $document );
?>

PHP:

 

hey thanks krakjoe. however the code doesn't work when somen types www.example.com without the http://.
i need something that will work when someone includes or doesn't include the http.