function change_url_to_link($str)
{
 $str = preg_replace('/(w{3}\.(\S*))/i','\1',$str);

 return $str;
}

function callback_url($matches)
{
 if (strlen($matches[1]) > 50)
 {
  $link_text = substr($matches[1],0,45) . "...";
 }
 else
 {
  $link_text = $matches[1];
 }

 return "<a href=\"http://".$matches[1]."\" target=\"blank\" class=\"fliesstext\">" . $link_text . "</a>";
}


function change_url_to_link($str)
{
 $str = preg_replace_callback("/(w{3}\.(\S*))/i", "callback_url", $str);
 return $str;
}