php过滤特殊字符,仅保留中文、字母、数字、下划线的函数 ``` function match_chinese($chars,$encoding='utf8') { $pattern = ($encoding=='utf8')?'/[\x{4e00}-\x{9fa5}a-zA-Z0-9_]/u':'/[\x80-\xFF]/'; preg_match_all($pattern,$chars,$result); $temp = join('',$result[0]); return $temp; } //使用方法 $nickname='qipa250.com'; $nickname = match_chinese($nickname); ``` php如何用正则表达式匹配中文