DateTime::setTimezone()

date_timezone_set

(PHP 5 >= 5.2.0, PHP 7)

设置 DateTime 对象的时区

说明

面向对象风格
publicDateTime::setTimezone(DateTimeZone$timezone): DateTime

过程化风格
date_timezone_set(DateTime$object,DateTimeZone$timezone): DateTime

设置DateTimeobject的时区。

参数

$object

仅过程化风格：由date_create()返回的DateTime类型的对象。此函数会修改这个对象。

$timezone

DateTimeZone对象，表示要设置为时区。

返回值

返回被修改的 DateTime 对象，或者在失败时返回FALSE.

更新日志

范例

Example #1DateTime::setTimeZone()例程

面向对象风格

<?php
$date = new DateTime('2000-01-01', new DateTimeZone('Pacific/Nauru'));
echo $date->format('Y-m-d H:i:sP') . "\n";
$date->setTimezone(new DateTimeZone('Pacific/Chatham'));
echo $date->format('Y-m-d H:i:sP') . "\n";
?>

过程化风格

<?php
$date = date_create('2000-01-01', timezone_open('Pacific/Nauru'));
echo date_format($date, 'Y-m-d H:i:sP') . "\n";
date_timezone_set($date, timezone_open('Pacific/Chatham'));
echo date_format($date, 'Y-m-d H:i:sP') . "\n";
?>

以上例程会输出：

2000-01-01 00:00:00+12:00
2000-01-01 01:45:00+13:45

参见

• DateTime::getTimezone() Return time zone relative to given DateTime
• DateTimeZone::__construct() 创建新的DateTimeZone对象

In response to the other comments expressing surprise that changing the timezone does not affect the timestamp:
A UNIX timestamp is defined as the number of seconds that have elapsed since 00:00:00 (UTC), Thursday, 1 January 1970.
So: with respect to UTC. Always.
Calling setTimezone() never changes the actual "absolute", underlying, moment-in-time itself. It only changes the timezone you wish to "view" that moment "from". Consider the following:
<?php
// A time in London.
$datetime = new DateTime('2015-06-22T10:40:25', new DateTimeZone('Europe/London'));
// I wonder how that SAME moment-in-time would 
// be described in other places around the world.
$datetime->setTimezone(new DateTimeZone('Australia/Sydney'));
print $datetime->format('Y-m-d H:i:s (e)');
 // 2015-06-22 19:40:25 (Australia/Sydney)
$datetime->setTimezone(new DateTimeZone('America/New_York'));
print $datetime->format('Y-m-d H:i:s (e)');
 // 2015-06-22 05:40:25 (America/New_York)
$datetime->setTimezone(new DateTimeZone('Asia/Calcutta'));
print $datetime->format('Y-m-d H:i:s (e)');
 // 2015-06-22 15:10:25 (Asia/Calcutta)
?>
Please note that ALL of these date strings unambiguously represent the exact same moment-in-time. Therefore, calling getTimestamp() at any stage will return the same result:
<?php
$datetime->getTimestamp();
 // 1434966025
?>

The timestamp value represented by the DateTime object is not modified when you set the timezone using this method. Only the timezone, and thus the resulting display formatting, is affected.
This can be seen using the following test code:
<?php
$MNTTZ = new DateTimeZone('America/Denver');
$ESTTZ = new DateTimeZone('America/New_York');
$dt = new DateTime('11/24/2009 2:00 pm', $MNTTZ);
var_dump($dt->format(DATE_RFC822), $dt->format('U'));
$dt->setTimezone($ESTTZ);
var_dump($dt->format(DATE_RFC822), $dt->format('U'));
/** Output:
string(29) "Tue, 24 Nov 09 14:00:00 -0700"
string(10) "1259096400"
string(29) "Tue, 24 Nov 09 16:00:00 -0500"
string(10) "1259096400"
**/
?>
As such, you can use this to easily convert between timezones for display purposes.

Surprising that the timezone works only specified in the separated method in case if you'll use ->format('U').
this does NOT apply timezone +0200 in the $timestamp:
<?php
  $date = new \DateTime(strtotime(time()), new DateTimeZone(system('date +%z')));
  $timestamp = $date->format('U');
?>
this will apply timezone +0200 in the $timestamp:
<?php
  $date = new \DateTime(strtotime(time()));
  $date->setTimezone(new DateTimeZone(system('date +%z')));
  $timestamp = $date->format('U');
?>

<?php
$MNTTZ = new DateTimeZone('America/Denver');
$ESTTZ = new DateTimeZone('America/New_York');
$dt = new DateTime('11/24/2009 2:00 pm', $MNTTZ);
var_dump($dt->format(DATE_RFC822), $dt->format('U'));
$dt->setTimezone($ESTTZ);
var_dump($dt->format(DATE_RFC822), $dt->format('U'));
?>
doesn't changes timestamp
But
<?php
$MNTTZ = new DateTimeZone('America/Denver');
$ESTTZ = new DateTimeZone('-0500');
$dt = new DateTime('11/24/2009 2:00 pm', $MNTTZ);
var_dump($dt->format(DATE_RFC822), $dt->format('U'));
$dt->setTimezone($ESTTZ);
var_dump($dt->format(DATE_RFC822), $dt->format('U'));
?>
changes timestamp
It is possible to fix that by:
<?php
$timestamp = $date->getTimestamp();
$date->setTimezone($value);
$date->setTimestamp($timestamp);
?>
But WTF???

It appears that what forzi at mail333 dot com said is correct.
When you reset the timezone on a DateTime object using a timezone that was instantiated with a GMT offset (e.g. <?php new DateTimeZone('-0500'); ?>) the timestamp as reported by <?php $dt->format('U'); ?> changes. 
However, the value reported by <?php $dt->getTimestamp(); ?> does _not_ change. Interestingly, once <?php $dt->getTimestamp(); is called, the value from <?php $dt->format('U'); ?> starts returning the correct timestamp. This appears to be a bug.
In any case, other output values from format() seem to be accurate, and the true timestamp is always accessible via getTimestamp().

I found unexpected behaviour when passing a timestamp.
timezone seems to always be GMT+0000 unless setTimezone() is set.
<?php
$MNTTZ = new DateTimeZone('America/Denver');
$ts = 1336476757;
$dt = new DateTime("@$ts", $MNTTZ);
var_dump($dt->format('T'), $dt->format('U'));
$dt->setTimezone($MNTTZ);
var_dump($dt->format('T'), $dt->format('U'));
/** Output:
string(8) "GMT+0000"
string(10) "1336476757"
string(3) "MDT"
string(10) "1336476757"
**/
?>