Close dangling HTML tags (See related posts)

Close open HTML tags, e.g. if you allow HTML in your comments. Not quite as robust as running it through tidy, but tidy is not always available.

function close_dangling_tags($html){
  #put all opened tags into an array
  preg_match_all("#<([a-z]+)( .*)?(?!/)>#iU",$html,$result);
  $openedtags=$result[1];

  #put all closed tags into an array
  preg_match_all("#</([a-z]+)>#iU",$html,$result);
  $closedtags=$result[1];
  $len_opened = count($openedtags);
  # all tags are closed
  if(count($closedtags) == $len_opened){
    return $html;
  }

  $openedtags = array_reverse($openedtags);
  # close tags
  for($i=0;$i < $len_opened;$i++) {
    if (!in_array($openedtags[$i],$closedtags)){
      $html .= '</'.$openedtags[$i].'>';
    } else {
      unset($closedtags[array_search($openedtags[$i],$closedtags)]);
    }
  }
  return $html;
}