Detecting browser type

function getBrowserType()
{
$agent = "";
$browser = "";
if(isset($_SERVER['HTTP_USER_AGENT']))
{
$agent = $_SERVER['HTTP_USER_AGENT'];
}

if(strlen(strstr($agent,'Safari')) > 0) {$browser = 'Safari';}
if (false) {}
elseif (strlen(strstr($agent,'Chrome')) > 0 ) {$browser = 'Chrome';}
elseif (strlen(strstr($agent,'Firefox')) > 0 ) {$browser = 'Firefox';}
elseif(strlen(strstr($agent,'MSIE')) > 0 ) {$browser = 'Internet Explorer';}
elseif(strlen(strstr($agent,'Safari')) > 0 ) {$browser = 'Safari';}
else {$browser="?";}
return $browser;
}