static $userAgent = '';

static function getUserAgent()
{
$header = getallheaders();
self :: $userAgent = $header['User-Agent'];
}
function findUserAgentByKey($ua,$key)
{
$len = strlen($key);
$start = strpos($ua,$key);

$pos = strpos($ua,' ',$start + $len + 1);

return substr($ua,$start + $len,$pos - $len - $start);
}
static function detectUserAgent()
{
self :: getUserAgent();

if (strpos(self :: $userAgent,'MSIE') != null)
{
self :: $version[] = IE;
self :: $version[] =self:: findUserAgentByKey(self :: $userAgent,'MSIE');
}
else if (strpos(self :: $userAgent,'Gecko/') != null)
{ self :: $version[] = FIREFOX;
self :: $version[] =self:: findUserAgentByKey(self :: $userAgent,'Firefox/');
}
else if (strpos(self :: $userAgent,'AppleWebKit/') != null)
{
self :: $version[] = CHROME;
self :: $version[] = self:: findUserAgentByKey(self :: $userAgent,'Chrome/');
}
else if (strpos(self :: $userAgent,'Presto/') != null)
{
self :: $version[] = OPERA;
self :: $version[] = self:: findUserAgentByKey(self :: $userAgent,'Opera/');
}
else
{
}

return self :: $version;
}

function matchUserAgent($ua,$key)
{
preg_match("/$key.([^\s]*?)\s/",$ua,$out);

return $out[1];
}
}
$ua=UserAgentDetect::detectUserAgent();

print_r($ua);