<?php
$message = "Lorem ipsum dolor sit amet, consectetur http://www.adipiscing.nl elit. Etiam sit amet http://www.odio.com leo. Mauris vitae sem sed diam ultricies egestas semper a risus. Mauris sem tortor, hendrerit eget aliquet ac, lacinia in tortor. http://www.Aenean.co.uk mauris nibh, luctus sit amet ipsum aliquet, vestibulum aliquam sem. Cras non felis sodales, pretium augue non, porttitor tortor.";
$words = explode(" ", $message);
$_words = array();
foreach($words as $word){
if(filter_var($word, FILTER_VALIDATE_URL) === false){
$_words[] = $word;
}
else{
$_words[] = "<a href=\"$word\">$word</a>";
}
}
echo implode(" ", $_words);