(PHP 5 >= 5.5.0, PHP 7, PHP 8)
DateTimeImmutable::add — Returns a new object, with added amount of days, months, years, hours, minutes and seconds
Creates a new DateTimeImmutable object, and adds the specified DateInterval object to this, to represent the new value.
interval
A DateInterval object
返回带有修改数据的新 DateTimeImmutable 对象。
示例 #1 DateTimeImmutable::add() example
面向对象风格
<?php
$date = new DateTimeImmutable('2000-01-01');
$newDate = $date->add(new DateInterval('P10D'));
echo $newDate->format('Y-m-d') . "\n";
?>示例 #2 Further DateTimeImmutable::add() examples
<?php
$date = new DateTimeImmutable('2000-01-01');
$newDate = $date->add(new DateInterval('PT10H30S'));
echo $newDate->format('Y-m-d H:i:s') . "\n";
$date = new DateTimeImmutable('2000-01-01');
$newDate = $date->add(new DateInterval('P7Y5M4DT4H3M2S'));
echo $newDate->format('Y-m-d H:i:s') . "\n";
?>以上示例会输出：
2000-01-01 10:00:30 2007-06-05 04:03:02
示例 #3 Beware when adding months
<?php
$date = new DateTimeImmutable('2000-12-31');
$interval = new DateInterval('P1M');
$newDate1 = $date->add($interval);
echo $newDate1->format('Y-m-d') . "\n";
$newDate2 = $newDate1->add($interval);
echo $newDate2->format('Y-m-d') . "\n";
?>以上示例会输出：
2001-01-31 2001-03-03