(PHP 5 >= 5.2.0)
DateTimeZone::getOffset -- timezone_offset_get — Returns the timezone offset from GMT
面向对象风格
过程化风格
This function returns the offset to GMT for the date/time specified in the
datetime parameter. The GMT offset is calculated
with the timezone information contained in the DateTimeZone object being used.
object仅过程化风格：由 timezone_open() 返回的 DateTimeZone 对象。
datetime
DateTime that contains the date/time to compute the offset from.
Returns time zone offset in seconds on success 或者在失败时返回 FALSE.
Example #1 DateTimeZone::getOffset() examples
<?php
// Create two timezone objects, one for Taipei (Taiwan) and one for
// Tokyo (Japan)
$dateTimeZoneTaipei = new DateTimeZone("Asia/Taipei");
$dateTimeZoneJapan = new DateTimeZone("Asia/Tokyo");
// Create two DateTime objects that will contain the same Unix timestamp, but
// have different timezones attached to them.
$dateTimeTaipei = new DateTime("now", $dateTimeZoneTaipei);
$dateTimeJapan = new DateTime("now", $dateTimeZoneJapan);
// Calculate the GMT offset for the date/time contained in the $dateTimeTaipei
// object, but using the timezone rules as defined for Tokyo
// ($dateTimeZoneJapan).
$timeOffset = $dateTimeZoneJapan->getOffset($dateTimeTaipei);
// Should show int(32400) (for dates after Sat Sep 8 01:00:00 1951 JST).
var_dump($timeOffset);
?>
skanzow at gmx dot net (2011-09-08 06:55:53)
A common problem is to format dates and times for XML documents.
The XML standard is defined as follows:
"
To specify a time zone, you can either enter a dateTime in UTC time by adding a "Z" behind the time - like this:
<startdate>2002-05-30T09:30:10Z</startdate>
or you can specify an offset from the UTC time by adding a positive or negative time behind the time - like this:
<startdate>2002-05-30T09:30:10-06:00</startdate>
"
Here is a possible solution in PHP:
<?php
if(date_default_timezone_get() == 'UTC') {
$offsetString = 'Z'; // No need to calculate offset, as default timezone is already UTC
} else {
$phpTime = '2002-05-30 09:30:10';
$millis = strtotime($phpTime); // Convert time to milliseconds since 1970, using default timezone
$timezone = new DateTimeZone(date_default_timezone_get()); // Get default system timezone to create a new DateTimeZone object
$offset = $timezone->getOffset(new DateTime($phpTime)); // Offset in seconds to UTC
$offsetHours = round(abs($offset)/3600);
$offsetMinutes = round((abs($offset) - $offsetHours * 3600) / 60);
$offsetString = ($offset < 0 ? '-' : '+')
. ($offsetHours < 10 ? '0' : '') . $offsetHours
. ':'
. ($offsetMinutes < 10 ? '0' : '') . $offsetMinutes;
}
echo('<startdate>' . date('Y-m-d\TH:i:s', $millis) . $offsetString . '</startdate>'); // This is the correct XML format
?>