function url2hyperlink($text) {
  $pattern = '#(^|[^\"=]{1})(http://|ftp://|mailto:|news:)([^\s<>]+)([\s\n<>]|$)#sm';
  $text = preg_replace($pattern,"\\1<a href=\"\\2\\3\">\\2\\3</a>\\4",$text);
  
  return $text;
}