PHP转换文件夹下所有文件编码

代码如下：

$value)
            {
                iconv_file($value);
            }
        }
        else
        {
            $contents_before = file_get_contents($filename);
            /*$encoding = mb_detect_encoding($contents_before,array('CP936','ASCII','GBK','GB2312','UTF-8'));
            echo $encoding;
            if($encoding=='UTF-8')  mb_detect_encoding函数不工作
            {
                return;
            }*/
            $contents_after = iconv($input_encoding,$output_encoding,$contents_before);
            file_put_contents($filename, $contents_after);
        }
    }
    else
    {
        echo '参数错误';
        return false;
    }
}
iconv_file('./test');
?>