用PHP判断客户端是否是手机

<?php
function isMobile(){
    $useragent = isset($_SERVER['HTTP_USER_AGENT'])? $_SERVER['HTTP_USER_AGENT']: '';
    $mobile_list = array('Google Wireless Transcoder','Windows CE','WindowsCE',
        'Symbian', 'Android','armv6l','armv5','Mobile','CentOS','mowser',
        'AvantGo','Opera Mobi','J2ME/MIDP',
        'Smartphone','Go.Web','Palm','iPAQ',
        'Profile/MIDP', 'Configuration/CLDC-',
        '160×160','176×220','240×240','240×320','320×240',
        'UP.Browser','UP.Link','SymbianOS','PalmOS','PocketPC','SonyEricsson',
        'Nokia','BlackBerry','Vodafone',
        'BenQ','Novarra-Vision','Iris','NetFront','HTC_','Xda_','SAMSUNG-SGH',
        'Wapaka','DoCoMo','iPhone','iPod'
    );
    foreach($mobile_list as $keyword){
        if(false !== strpos($useragent, $keyword)){
            return true;
        }
    }
    return false;
}
echo isMobile()? 'mobile': 'pc';