date_default_timezone_get()

(PHP 5 >= 5.1.0, PHP 7)

取得一个脚本中所有日期时间函数所使用的默认时区

说明

date_default_timezone_get(void): string

本函数返回默认时区，使用如下“假定”的顺序：

• 用date_default_timezone_set()函数设定的时区（如果设定了的话）

• 仅仅在 PHP 5.4.0 之前：TZ环境变量（如果非空）

• date.timezone配置选项（如果设定了的话）

• 仅仅在 PHP 5.4.0 之前：查询操作系统主机(如果操作系统支持并允许)。 This uses an algorithm that has toguessthe timezone. This is by no means going to work correctly for every situation. A warning is shown when this stage is reached. Do not rely on it to be guessed correctly, and setdate.timezoneto the correct timezone instead.

• 如果以上选择都不成功，date_default_timezone_get()会则返回UTC的默认时区。

返回值

返回一个string。

更新日志

范例

获取默认时区

<?php
date_default_timezone_set('Europe/London');
if (date_default_timezone_get()) {
    echo 'date_default_timezone_set: ' . date_default_timezone_get() . '<br />';
}
if (ini_get('date.timezone')) {
    echo 'date.timezone: ' . ini_get('date.timezone');
}
?>

以上例程的输出类似于：

date_default_timezone_set: Europe/London
date.timezone: Europe/London

获取一个时区的简写

<?php
date_default_timezone_set('America/Los_Angeles');
echo date_default_timezone_get() . ' => ' . date('e') . ' => ' . date('T');
?>

以上例程会输出：

America/Los_Angeles => America/Los_Angeles => PST

参见

• date_default_timezone_set() 设定用于一个脚本中所有日期时间函数的默认时区
• 所支持的时区列表

Please note that on Debian/Ubuntu this function will return the system timezone defined in /etc/localtime if date.timezone is not defined, even with PHP 5.4+
See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=673763#10

In my case, I'm not sure I can guess the correct timezone any better than PHP and it's no where near important enough to nag the user, so...
<?php
// Suppress DateTime warnings
date_default_timezone_set(@date_default_timezone_get());
?>

Please note that "Damien dot Garrido dot Work at gmail dot com" code is wrong, the third parameter of sprintf must be divided by 60.
This is the corrected function:
<?php
function timezone_offset_string( $offset )
{
    return sprintf( "%s%02d:%02d", ( $offset >= 0 ) ? '+' : '-', abs( $offset / 3600 ), abs( $offset % 3600 ) / 60 );
}
?>

To get offset string from offset:
<?php
function timezone_offset_string( $offset )
{
    return sprintf( "%s%02d:%02d", ( $offset >= 0 ) ? '+' : '-', abs( $offset / 3600 ), abs( $offset % 3600 ) );
}
$offset = timezone_offset_get( new DateTimeZone( 'Pacific/Kiritimati' ), new DateTime() );
echo "offset: " . timezone_offset_string( $offset ) . "\n";
$offset = timezone_offset_get( new DateTimeZone( 'Pacific/Tahiti' ), new DateTime() );
echo "offset: " . timezone_offset_string( $offset ) . "\n";
?>
Output:
offset: +14:00
offset: -10:00

For the reason that date_default_timezone_get() throws an error when the timezone isn't set in php.ini and then returns a default chosen by the system (rather than returning false to indicate to the script that a timezone hasn't been set), I've found that the following works when you want a script to detect when the ini value has not been set and want the script itself to choose a default in that case, while still allowing bootstrap scripts to set their own default using date_default_timezone_set().
<?php
set_error_handler(function ($errno, $errstr){
  throw new Exception($errstr);
  return false;
});
try{
  date_default_timezone_get();
}
catch(Exception $e){
  date_default_timezone_set('UTC'); // Sets to UTC if not specified anywhere in .ini
}
restore_error_handler();

If you want to get the abbrivation (3 or 4 letter), instead of the long timezone string you can use date('T') function like this:
Input:
date_default_timezone_set('America/Los_Angeles');
echo date_default_timezone_get();
echo ' => '.date('e');
echo ' => '.date('T');
Output:
America/Los_Angeles => America/Los_Angeles => PST

date_default_timezone_get() will still emit a warning in E_STRICT if the timezone is not set; either by date_default_timezone_set() or the ini option of date.timezone.
This is probably not a big deal, but I thought I would contribute what I found.