ฟังก์ชั่นตัดข้อความ HTML

<?
function html_strlen($str) {
  $chars = preg_split('/(&[^;\s]+;)|/', $str, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
  return count($chars);
}

function html_substr($str, $start, $length = NULL) {
  if ($length === 0) return ""; //stop wasting our time ;)

  //check if we can simply use the built-in functions
  if (strpos($str, '&') === false) { //No entities. Use built-in functions
    if ($length === NULL)
      return substr($str, $start);
    else
      return substr($str, $start, $length);
  }

  // create our array of characters and html entities
  $chars = preg_split('/(&[^;\s]+;)|/', $str, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_OFFSET_CAPTURE);
  $html_length = count($chars);

  // check if we can predict the return value and save some processing time
  if (($html_length === 0) /* input string was empty */
    || ($start >= $html_length) /* $start is longer than the input string */
    || (isset($length) and ($length <= -$html_length)) /* all characters would be omitted */
    ) return "";

  //calculate start position
  if ($start >= 0) {
    $real_start = $chars[$start][1];
  } else { //start'th character from the end of string
    $start = max($start,-$html_length);
    $real_start = $chars[$html_length+$start][1];
  }

  if (!isset($length)) // no $length argument passed, return all remaining characters
    return substr($str, $real_start);
  else if ($length > 0) { // copy $length chars
    if ($start+$length >= $html_length) { // return all remaining characters
      return substr($str, $real_start);
    } else { //return $length characters
      return substr($str, $real_start, $chars[max($start,0)+$length][1] - $real_start);
    }
  } else { //negative $length. Omit $length characters from end
    return substr($str, $real_start, $chars[$html_length+$length][1] - $real_start);
  }
};
?>