This method returns an associative array containing some 'major' timezones (like CEST), which on their own contain more specific 'geographic' timezones (like Europe/Amsterdam).
If you're using these timezones and their offset/DST information, it's extremely important to realize the following:
*It seems like ALL DIFFERENT OFFSET/DST CONFIGURATIONS (including historical configurations) of each timezone are included!*
For example, Europe/Amsterdam can be found six times in the output of this function. Two occurrences (offset 1172/4772) are for the Amsterdam time used until 1937; two (1200/4800) are for the time that was used between 1937 and 1940; and two (3600/4800) are for the time used since 1940.
*Therefore, YOU CANNOT RELY ON THE OFFSET/DST INFORMATION RETURNED BY THIS FUNCTION as being currently correct/in use!*
If you want to know the current offset/DST of a certain timezone, you'll have to do something like this:
<?php
$now = new DateTime(null, new DateTimeZone('Europe/Amsterdam'));
echo $now->getOffset();
?>
P.S. I'm sorry for my use of caps lock in this post, but as this behavior is not described in the documentation, I considered it to be important enough to shout. Normally I don't do such things :)
DateTimeZone::listAbbreviations
timezone_abbreviations_list
(PHP 5 >= 5.2.0, PHP 7, PHP 8)
DateTimeZone::listAbbreviations -- timezone_abbreviations_list — Returns associative array containing dst, offset and the timezone name
Description
Object-oriented style
Procedural style
The returned list of abbreviations includes all historical use of
abbreviations, which can lead to correct, but confusing entries.
There are also conflicts, as PST is used both in the US
and in the Philippines.
The list that this function returns is therefore not suitable for building an array with options to present a choice of timezone to users.
Note:
The data for this function are precompiled for performance reasons, and are not updated when using a newer » timezonedb.
Parameters
This function has no parameters.
Return Values
Returns the array of timezone abbreviations.
Examples
Example #1 A timezone_abbreviations_list() example
<?php
$timezone_abbreviations = DateTimeZone::listAbbreviations();
print_r($timezone_abbreviations["acst"]);
?>The above example will output something similar to:
Array
(
[0] => Array
(
[dst] => 1
[offset] => -14400
[timezone_id] => America/Porto_Acre
)
[1] => Array
(
[dst] => 1
[offset] => -14400
[timezone_id] => America/Eirunepe
)
[2] => Array
(
[dst] => 1
[offset] => -14400
[timezone_id] => America/Rio_Branco
)
[3] => Array
(
[dst] => 1
[offset] => -14400
[timezone_id] => Brazil/Acre
)
)
add a note
User Contributed Notes 2 notes
jonathan at hogervorst dot info ¶
10 years ago
kingskippus at gmail dot com ¶
15 years ago
Note that the dst field is of boolean type, so if you are doing an identity comparison, you need to test for true or false, not 0 or 1. For example:
<?php
$timezone_abbreviations = DateTimeZone::listAbbreviations();
foreach ($timezone_abbreviations["est"] as $tz) {
echo $tz['timezone_id'];
// if ($tz['dst'] === 1) will always evaluate to false
if ($tz['dst'] === true) {
echo " (DST observed)<br />\n";
}
// Could use else here, but for illustration...
if ($tz['dst'] === false) {
echo " (DST not observed)<br />\n";
}
}
?>
