Codice PHP:
session_start();
$mobile_browser = '0';
//ctr USER_AGENT ed eventualmente incremento la variabile
if (preg_match('/(up.browser|up.link|mmp|symbian|smartphone|midp|wap|phone|android)/i', strtolower($_SERVER['HTTP_USER_AGENT']))) $mobile_browser++;
//ctr HTTP_ACCEPT corrisponde alla tecnologia WAP per telefonini
if ((strpos(strtolower($_SERVER['HTTP_ACCEPT']),'application/vnd.wap.xhtml+xml') > 0)
or ((isset($_SERVER['HTTP_X_WAP_PROFILE']) or isset($_SERVER['HTTP_PROFILE'])))) $mobile_browser++;
// primi 4 caratteri da USER_AGENT e creo array con tutti i header mobile
$mobile_ua = strtolower(substr($_SERVER['HTTP_USER_AGENT'], 0, 4));
$mobile_agents = array(
'w3c ','acs-','alav','alca','amoi','audi','avan','benq','bird','blac',
'blaz','brew','cell','cldc','cmd-','dang','doco','eric','hipt','inno',
'ipaq','java','jigs','kddi','keji','leno','lg-c','lg-d','lg-g','lge-',
'maui','maxo','midp','mits','mmef','mobi','mot-','moto','mwbp','nec-',
'newt','noki','oper','palm','pana','pant','phil','play','port','prox',
'qwap','sage','sams','sany','sch-','sec-','send','seri','sgh-','shar',
'sie-','siem','smal','smar','sony','sph-','symb','t-mo','teli','tim-',
'tosh','tsm-','upg1','upsi','vk-v','voda','wap-','wapa','wapi','wapp',
'wapr','webc','winw','winw','xda ','xda-');
//se corrisponde a mobile aumento la variabile
if (in_array($mobile_ua,$mobile_agents)) $mobile_browser++;
if (strpos(strtolower($_SERVER['ALL_HTTP']),'OperaMini') > 0) $mobile_browser++;
if (strpos(strtolower($_SERVER['HTTP_USER_AGENT']),'windows') > 0) $mobile_browser = 0;
//setto la sessione ResponsiveWeb in base al controllo
if ($mobile_browser > 0) $_SESSION['ResponsiveWeb'] = "mobile";
else $_SESSION['ResponsiveWeb'] = "web";
In base a quello che ti restituisce valorizzi le variabili come vuoi