php符转换为HTML实体

function d_htmlspecialchars($string) { 
 if(is_array($string)) { 
  foreach($string as $key => $val) { 
   $string[$key] = d_htmlspecialchars($val); 
  }//开源代码phpfensi.com 
 } else { 
  $string = str_replace('&', '&', $string); 
  $string = str_replace('"', '"', $string); 
  $string = str_replace(''', ''', $string); 
  $string = str_replace('<', '&lt;', $string); 
  $string = str_replace('>', '&gt;', $string); 
  $string = preg_replace('/&amp;(#d;)/', '&1', $string); 
 } 
 return $string; 
}