A browser inspection class_PHP tutorial

//Original author: epsilon7
//SonyMusic(sonymusic@163.net)
class BrowserDetector {
var $UA = ""; //Content of $HTTP_USER_AGENT
var $BROWSER= "Unknown "; //Browser type
var $PLATFORM = "Unknown"; //Operating system
var $VERSION= ""; //Browser version number
var $MAJORVER = ""; // Browser major version number
var $MINORVER = ""; //Browser minor version number
/* Start constructor*/
function BrowserDetector(){
$this->UA = getenv(HTTP_USER_AGENT);
$preparens = "";
$parens = "";
$i = strpos($this->UA,"(");
if ($i >= 0) {
$preparens = trim(substr($this->UA,0,$i));
$parens = substr($this->UA,$i+1, strlen($this->UA));
$j = strpos($parens,")");
if($j>=0) {
$parens = substr($parens, 0,$j);
}
}
else {
$preparens = $this->UA;
}
$browVer = $preparens;
$token = trim(strtok($parens,";"));
while($token) {
if($token=="compatible") {
}
elseif(preg_match("/ MSIE/i","$token")) {
$browVer = $token;
}
elseif(preg_match("/Opera/i","$token")) {
$ browVer = $token; Linux/i","$token")) {
$this->PLATFORM = "Unix";
}
elseif(preg_match("/Win/i","$token")) {
$this->PLATFORM = $token;
}
elseif(preg_match("/Mac/i","$token") || preg_match("/PPC/i","$ token")) {
$this->PLATFORM = $token;
}
$token = strtok(";");
}
$msieIndex = strpos($browVer, "MSIE");
if($msieIndex >= 0) {
$browVer = substr($browVer,$msieIndex,strlen($browVer));
}
$leftover = " ";
if(substr($browVer,0,strlen("Mozilla")) == "Mozilla") {
$this->BROWSER = "Netscape";
$leftover=substr( $browVer,strlen("Mozilla")+1,strlen($browVer));
}
elseif(substr($browVer,0,strlen("Lynx")) == "Lynx") {
$this->BROWSER = "Lynx";
$leftover=substr($browVer,strlen("Lynx")+1,strlen($browVer));
}
elseif(substr ($browVer,0,strlen("MSIE")) == "MSIE") {
$this->BROWSER = "IE";
$leftover=substr($browVer,strlen("MSIE" )+1,strlen($browVer));
}
elseif(substr($browVer,0,strlen("Microsoft Internet Explorer")) == "Microsoft Internet Explorer") {
$this ->BROWSER = "IE";
$leftover=substr($browVer,strlen("Microsoft Internet Explorer")+1,strlen($browVer));
}
elseif(substr($ browVer,0,strlen("Opera")) == "Opera") {
$this->BROWSER = "Opera";
$leftover=substr($browVer,strlen("Opera")+ 1,strlen($browVer));
}
$leftover = trim($leftover);
$i=strpos($leftover," ");
if($i > 0 ) {
$this->VERSION = substr($leftover,0,$i);

http://www.bkjia.com/PHPjc/509060.html