包含左括号的正则表达式不起作用 - Regex containing opening bracket not working?

Regex containing opening bracket not working?

我在PHP中运行了一个简单的正则表达式，由于某种原因，它不适用于左括号。看：

 $str = 'sdfsf sdfs<link rel="stylesheet" id="editor-buttons-css" href="http://localhost/wordpress/wp-includes/css/editor.min.css?ver=3.6" type="text/css" media="all">sdfsd sdfsdl';
    $reg = '/<link['s'S]+eet/';
      preg_match($reg, $str, $re);
      print_r($re);
    // outputs: Array ( [0] => );
 $str = 'sdfsf sdfs<link rel="stylesheet" id="editor-buttons-css" href="http://localhost/wordpress/wp-includes/css/editor.min.css?ver=3.6" type="text/css" media="all">sdfsd sdfsdl';
    $reg = '/link['s'S]+eet/';
      preg_match($reg, $str, $re);
      print_r($re);
    // outputs: Array ( [0] => link rel="stylesheet );

如何让正则表达式与左括号一起使用？

实际上它输出

Array ( [0] => <link rel="stylesheet )

但是浏览器解析了 HTML，请尝试echo htmlspecialchars（print_r（$re，true））;