Converting date and time considering DTS

Question

I need to convert a date to GMT, and I was considering relying on this script (derived from what found in date_default_timezone_set documentation's comments (http://us.php.net/manual/en/function.date-default-timezone-set.php):

$userDate = "2012-12-05 12:13:41";
$userTimezone = "America/New_York";
$dateResult = convertDate($userDate, $userTimezone);

function convertDate($dateOrigin, $timezoneOrigin) {
    $date = new DateTime($dateOrigin, new DateTimeZone($timezoneOrigin)); 
    date_default_timezone_set('Europe/London'); 
    return date("Y-m-d h:i:s", $date->format('U'));
}

But I was wondering, the above code would consider daylight time saving changes? I mean, given the user's timezone and date, when converting to another timezone, does the above code considers the differences that may occur because of DTS?

Answer 1

After some testing the answer is no. The conversion using the above code does not consider DTS changes. So I guess that code is pretty much useless.