php匹配中文字符

$str = '写一个hello world程序';//GBK/GB2312使用：$result = preg_match_all("/[\x80-\xff]+/", $str, $matches);// UTF-8 使用：$result = preg_match_all("/[\x{4e00}-\x{9fa5}]+/u", $str, $matches);echo '<pre>';print_r($matches);exit;

结果都是：

Array(    [0] => Array        (            [0] => 写一个            [1] => 程序        ))