DateTimeZone::getOffset

timezone_offset_get

(PHP 5 >= 5.2.0)

DateTimeZone::getOffset -- timezone_offset_getReturns the timezone offset from GMT

Description

Object oriented style

public int DateTimeZone::getOffset ( DateTime $datetime )

Procedural style

int timezone_offset_get ( DateTimeZone $object , DateTime $datetime )

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.

Parameters

object

Procedural style only: A DateTimeZone object returned by timezone_open()

datetime

DateTime that contains the date/time to compute the offset from.

Return Values

Returns time zone offset in seconds on success or FALSE on failure.

Examples

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);
?>

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User Contributed Notes 1 note

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skanzow at gmx dot net
3 years ago
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
?>
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