php//php 5.3-
if (!function_exists('preg_filter')) {

    function preg_filter($pattern, $replace, $subject, $limit = -1 , &$count = null) {

      if(!is_array($subject)) {
        $noArray = 1 ;
        $subject = array($subject);
      }

      $preg = preg_replace($pattern, $replace, $subject, $limit,  &$count);

      $diff = array_diff($preg, $subject);

      if($noArray == 1) $diff = implode($diff) ;

      return $diff ;

    }

  }

看下是不是PHP版本问题，这个函数应该是 5.3+之后的

preg_filter
(PHP 5 >= 5.3.0)
preg_filter — Perform a regular expression search and replace

可以用了，但前提必须是php5.3或以上的，都怪自己在编辑器里面没配置好才会出现这个错误的,I'm sorry~