How do you handle timezone difference calculation in PHP?

Question

I'm being told that this below method of calculating the user's local time is sometimes not working. What's the best way to do this in PHP? What do you do?

public function getTimeOffset ($time) {
    $this->_cacheTimeOffset();  
    if ($this->timeOffsetExecuted) {
        $d = date("O");
        $neg = 1;

        if (substr($d, 0, 1) == "-") {
            $neg = -1;
            $d = substr($d, 1);
        }

        $h = substr($d, 0, 2)*3600;
        $m = substr($d, 2)*60;

        return $time + ($neg * ($h + $m) * -1) + (($this->timeOffset + $this->getDstInUse()) * 3600);
    }
    return $time;
}

score 2 · Accepted Answer · edited Apr 23 '15 at 07:01

2

Use the DateTime extension, such as DateTime::getOffset,
or DateTimeZone::getOffset

Some countries might have perform several timezone update,
this method DateTimeZone::getTransitions reveal the transition history

edited Apr 23 '15 at 07:01

Qix - MONICA WAS MISTREATED

14,451
16
82
145

answered Nov 28 '10 at 21:43

ajreal

46,720
11
89
119

I'm currently allowing a user to specify their timezone in their profile. Are you saying that I should just be able to pull it dynamically via PHP and don't have to ask them their timezone? – Ben Nov 29 '10 at 14:34
1

@Webnet - You still need to user to place their current timezone into their profile. Probably, you can provide a list of timezone, and let let user to choose. `DateTimeZone::listIdentifiers` able to provide a full list of timezone supported, details - http://www.php.net/manual/en/datetimezone.listidentifiers.php – ajreal Nov 29 '10 at 18:28

score 1 · Answer 2 · edited Apr 23 '15 at 07:00

1

date('Z');

returns the UTC offset in seconds.

edited Apr 23 '15 at 07:00

Qix - MONICA WAS MISTREATED

14,451
16
82
145

answered Jan 08 '13 at 12:07

kachar

2,310
30
32

score 1 · Answer 3 · edited May 23 '17 at 10:10

Just answered a very similar question over here. I recommend you check that one out; I explained the two preferred ways of doing timezone offset calculation (using simple math, and then the datetimezone and datetime classes) pretty thoroughly.

The first way would be the easiest (and most logical) way, and that is to store their offset (if you already have it, that is) and multiply that by 3600 (1 hour in seconds), and then add that value to the current unix timestamp to get their final time of running.

Another way to do it is to use the DateTime and DateTimeZone classes. How these two classes work, as shown here, is that you create two DateTimeZone objects, one with your timezone and one with theirs; create two DateTime objects with the first parameters being "now" and the second being the reference to the DateTimeZone objects above (respectively); and then call the getOffset method on your timezone object passing their timezone object as the first parameter, ultimately getting you the offset in seconds that can be added to the current unix timestamp to get the time that their job needs to run.

score -1 · Answer 4 · answered Nov 28 '10 at 21:51

-1

A quick solution:

<?php echo date('g:i a', strtotime("now + 10 hours 30 minutes")); ?>

answered Nov 28 '10 at 21:51

RabidFire

6,280
1
28
24

This is only putting time formatting and does not relate to time zones at all. – Ben Dec 01 '10 at 15:19

How do you handle timezone difference calculation in PHP?

4 Answers4

Linked

Related