Why statistical functions don't work

Question

源码：

@header("content-Type: text/html; charset=utf-8");
$demon = 'www.php.cn';
$Chinese = 'PHP中文网';
echo strlen($demon),'<hr>';
echo strlen($Chinese),'<hr>';
echo mb_strlen($demon),'<hr>';
echo mb_strlen($Chinese),'<hr>';
echo mb_strwidth($demon),'<hr>';
echo mb_strwidth($Chinese),'<hr>';

输出：

10

12

10

12##%