how to identify request coming from mobile in php code example

Example: php detect mobile request

function isMobileDevice() {
    return preg_match("/(android|avantgo|blackberry|bolt|boost|cricket|docomo
|fone|hiptop|mini|mobi|palm|phone|pie|tablet|up\.browser|up\.link|webos|wos)/i"
, $_SERVER["HTTP_USER_AGENT"]);
}