(PHP 5 >= 5.5.0, PHP 7, PHP 8)
DateTimeImmutable::setISODate — Sets the ISO date
$year, int $week, int $dayOfWeek = 1): DateTimeImmutableReturns a new DateTimeImmutable object with the date set according to the ISO 8601 standard - using weeks and day offsets rather than specific dates.
yearYear of the date.
weekWeek of the date.
dayOfWeekOffset from the first day of the week.
Returns a new DateTimeImmutable object with the modified data.
Example #1 DateTimeImmutable::setISODate() example
Object-oriented style
<?php
$date = new DateTimeImmutable();
$newDate = $date->setISODate(2008, 2);
echo $newDate->format('Y-m-d') . "\n";
$newDate = $date->setISODate(2008, 2, 7);
echo $newDate->format('Y-m-d') . "\n";The above example will output:
2008-01-07 2008-01-13
Procedural style
<?php
$date = date_create();
date_isodate_set($date, 2008, 2);
echo date_format($date, 'Y-m-d') . "\n";
date_isodate_set($date, 2008, 2, 7);
echo date_format($date, 'Y-m-d') . "\n";The above example will output:
2008-01-07 2008-01-13
Example #2 Values exceeding ranges are added to their parent values
<?php
$date = new DateTimeImmutable();
$newDate = $date->setISODate(2008, 2, 7);
echo $newDate->format('Y-m-d') . "\n";
$newDate = $date->setISODate(2008, 2, 8);
echo $newDate->format('Y-m-d') . "\n";
$newDate = $date->setISODate(2008, 53, 7);
echo $newDate->format('Y-m-d') . "\n";The above example will output:
2008-01-13 2008-01-14 2009-01-04
Example #3 Finding the month a week is in
<?php
$date = new DateTimeImmutable();
$newDate = $date->setISODate(2008, 14);
echo $newDate->format('n');The above example will output:
3
note that giving a week out of range will produce a date for a different year
example:
<?php
$date = new DateTimeImmutable();
$newDate = $date->setISODate(2026, 53);
echo $newDate->format('Y-m-d') . "\n";
// will print "2026-12-28" (2026 has 53 weeks)
$newDate = $date->setISODate(2026, 54);
echo $newDate->format('Y-m-d') . "\n";
// will print 2027-01-04 which is the 1st week of 2027
?>