/**
* 多字节版 trim 函数，支持移除首尾 空格（全角、半角）、制表符、换行符。
*/
function mb_trim($str)
{
    $str = mb_ereg_replace(‘^(([ \r\n\t])*(　)*)*‘, ‘‘, $str);  
    $str = mb_ereg_replace(‘(([ \r\n\t])*(　)*)*$‘, ‘‘, $str);  
    return $str; 
}

1 <?php
2 $str = ‘asdasdasdasdsfsd地方所得税dfdfgfdfgdfgdfgf的发个梵蒂冈dfg‘;
3 preg_match_all("/[\x{4e00}-\x{9fa5}]+/u", $str, $chinese); //utf8编码
4 echo implode("", $chinese[0]);

<?php
   $str = ‘asdasdasdasdsfsd地方所得税dfdfgfdfgdfgdfgf的发个梵蒂冈dfg‘;
   preg_match_all("/[".chr(0xa1)."-".chr(0xff)."]+/", $str, $chinese); //gb2312编码
   echo implode("", $chinese[0]);