CODEWITHSUNDEEP
phptimezoneutcgmt
Eclipse
Eclipse

Reputation: 404

PHP timezone issue | BST and GMT

I have developed a piece of application which records when certain records where modified and created, so basically we take use of the time() function to record when a change is saved.

I am in the UK so my time-zone has to be GMT. However in the UK we use DST so in the summer we are no longer in GMT but in BST.

How would I change the timezone to be using BST (which is GMT +1). I would like to declare it in my php file so that it is easily changed. Here is what I have at the moment:

date_default_timezone_set("UTC");

When I change it to:

date_default_timezone_set("BST");

I get a php error Timezone ID 'BST' is invalid, and when I change it to Europe/London, it still stays as GMT rather then BST

Upvotes: 10

Views: 17185

Answers (5)

Kevin Doyle
Kevin Doyle

Reputation: 1

I'm using this for my literary clock at bigjobby.com/time/.

<?php

// Set the default timezone to UK
date_default_timezone_set('Europe/London');

// Get the current date and time
$now = new DateTime();

echo $now->format('Y-m-d H:i:s') . "\n";

// If you want to display the timezone
echo $now->getTimezone()->getName();
?>

Upvotes: 0

Martin
Martin

Reputation: 22760

There is an issue that Europe/London time-zone can be wrong by +/- 1 hour from the actual time in the real world in the UK .

$var = time();

See this example:

print date_default_timezone_get();
print "\n";
print date('r',1698136637);

By default PHP uses UTC time so this would be:

UTC
Tue, 24 Oct 2023 08:37:17 +0000

And through third party software for our records this is the correct time the date was set.

However, using Europe/London there is an issue:

date_default_timezone_set('Europe/London');
print date_default_timezone_get();
print "\n";
print date('r',1698136637);

Which gives:

Europe/London
Tue, 24 Oct 2023 09:37:17 +0100

This is not the correct time, as the time this record was made IN LONDON in the UK , the time was 8:37am.

Solution: use UTC rather than Europe/London time zones.

Upvotes: 0

Clain Dsilva
Clain Dsilva

Reputation: 1651

date_default_timezone_set("Europe/London");
echo date('Y-m-d H:i:s');

Use "Europe/London" instead of BST/GMT/UTC with date_default_timezone_set(), probably the right way to handle time for an instance. This way, the timezone time is preserved throughout the time the page instance is active.

Upvotes: 1

Matt Johnson-Pint
Matt Johnson-Pint

Reputation: 241693

The time() function returns a unix timestamp, which is always going to be based on UTC (which is the same as GMT). It would be invalid for it to be adjusted for BST, or for any other time zone.

There are other functions for working with local time, and for converting the unix timestamp to a string for display. That is where you use the Europe/London time zone.

BST is not valid, because it could stand for "Bangladesh Standard Time", or a handful of other time zones. In general, don't rely on time zone abbreviations.

Upvotes: 1

deceze
deceze

Reputation: 522372

You would be setting your timezone to Europe/London, which automatically transitions between GMT and BST at the appropriate dates. The timezone includes this information, that's basically the point of timezones (in the PHP sense).

The PHP manual handily includes exactly this as a sample:

$timezone = new DateTimeZone("Europe/London");
$transitions = $timezone->getTransitions();
print_r(array_slice($transitions, 0, 3));

Array
(
    [0] => Array
        (
            [ts] => -9223372036854775808
            [time] => -292277022657-01-27T08:29:52+0000
            [offset] => 3600
            [isdst] => 1
            [abbr] => BST
        )

    [1] => Array
        (
            [ts] => -1691964000
            [time] => 1916-05-21T02:00:00+0000
            [offset] => 3600
            [isdst] => 1
            [abbr] => BST
        )

    [2] => Array
        (
            [ts] => -1680472800
            [time] => 1916-10-01T02:00:00+0000
            [offset] => 0
            [isdst] => 
            [abbr] => GMT
        )

)

Upvotes: 11

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