bbcode解析时遇见的两个有关问题

<div style="color:red">dddd</div><br />

<br><br><?php <br />class BBCode {  <br>    public function __construct(){}<br>    private function showBBcodes($text) {<br>        // BBcode array<br>        $find = array(<br>            '~\[b\](.*?)\[/b\]~s',<br>            '~\[i\](.*?)\[/i\]~s',<br>            '~\[u\](.*?)\[/u\]~s',<br>            '~\[quote\](.*?)\[/quote\]~s',<br>            '~\[table\](.*?)\[/table\]~s',<br>            '~\[tr\](.*?)\[/tr\]~s',<br>            '~\[td\](.*?)\[/td\]~s',<br>            '~\[justify\](.*?)\[/justify\]~s',<br>            '~\[center\](.*?)\[/center\]~s',<br>            '~\[right\](.*?)\[/right\]~s',<br>            '~\[left\](.*?)\[/left\]~s',<br>            '~\[size=(.*?)\](.*?)\[/size\]~s',<br>            '~\[color=(.*?)\](.*?)\[/color\]~s',<br>            '~\[font=(.*?)\](.*?)\[/font\]~s',<br>            '~\[url=((?:ftp|https?)://.*?)\](.*?)\[/url\]~s',<br>            '~\[img\](https?://.*?\.(?:jpg|jpeg|gif|png|bmp))\[/img\]~s',<br>            '/\[img=(\d+)x(\d+)\](.*?)\[\/img\]/is',<br>            '~\[youtube\](.*?)\[/youtube\]~s',<br>        );<br><br>        // HTML tags to replace BBcode<br>        $replace = array(<br>            '<b>$1</b>',<br>            '<i>$1</i>',<br>            '<span>$1</span>',<br>            '<pre class="brush:php;toolbar:false;">$1'.'pre&gt;',<br>            '