PHP judge the user is the phone side? or browser-side access?

function IsMobile () {$useragent =isset ($_server[' http_user_agent '])? $_server[' Http_user_agent ']: ';           $useragent _commentsblock=preg_match (' |\ (. *?\) | ', $useragent, $matches) >0? $matches [0]: ';                  function Checksubstrs ($substrs, $text) {foreach ($substrs as $substr) if (False!==strpos ($text, $substr)) {             return true;     } return false; } $mobile _os_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 '); $mobile _token_list=array (' PROFILE/MIDP ', ' configuration/cldc-', ' 160x160 ', ' 176x220 ', ' 240x240 ', ' 240x320 ', ' the ' ', ' up. Browser ', ' up. Link ', ' SymbianOS ', ' PalmOS ', ' PocketPC ', ' SonyEricsson ', ' Nokia ', ' BlackBerry ', ' Vodafone ', ' BenQ ', ' novarra-vision ', '      Iris ', ' NetFront ', ' htc_ ', ' Xda_ ', ' samsung-sgh ', ' Wapaka ', ' DoCoMo ', ' iPhone ', ' iPod '; $found _mobile = checksubstrs ($mobile _os_list, $uSeragent_commentsblock) | |      Checksubstrs ($mobile _token_list, $useragent);     if ($found _mobile) {return true;     }else{return false; }}if (IsMobile ()) {header (' Location:./app/index.php ');//If it is the mobile side, perform a jump}else{header (' Location:./web/index.php ');//If Non-Mobile, execute jump}

Reproduced in this article: HTTP://BBS.ITHEIMA.COM/THREAD-337540-1-1.HTML?MXHW

PHP judge the user is the phone side? or browser-side access?