(PHP 5 >= 5.3.0)
DateTime::add -- date_add — Adds an amount of days, months, years, hours, minutes and seconds to a DateTime object
object
仅过程化风格：由 date_create() 返回的 DateTime 类型的对象。此函数会修改这个对象。
interval
A DateInterval object
返回被修改的 DateTime 对象， 或者在失败时返回 FALSE.
Example #1 DateTime::add() example
面向对象风格
<?php
$date = new DateTime('2000-01-01');
$date->add(new DateInterval('P10D'));
echo $date->format('Y-m-d') . "\n";
?>
过程化风格
<?php
$date = date_create('2000-01-01');
date_add($date, date_interval_create_from_date_string('10 days'));
echo date_format($date, 'Y-m-d');
?>
以上例程会输出：
2000-01-11
Example #2 Further DateTime::add() examples
<?php
$date = new DateTime('2000-01-01');
$date->add(new DateInterval('PT10H30S'));
echo $date->format('Y-m-d H:i:s') . "\n";
$date = new DateTime('2000-01-01');
$date->add(new DateInterval('P7Y5M4DT4H3M2S'));
echo $date->format('Y-m-d H:i:s') . "\n";
?>
以上例程会输出：
2000-01-01 10:00:30 2007-06-05 04:03:02
Example #3 Beware when adding months
<?php
$date = new DateTime('2000-12-31');
$interval = new DateInterval('P1M');
$date->add($interval);
echo $date->format('Y-m-d') . "\n";
$date->add($interval);
echo $date->format('Y-m-d') . "\n";
?>
以上例程会输出：
2001-01-31 2001-03-03
DateTime::modify() is an alternative when using PHP 5.2.
Anonymous (2011-02-01 14:16:10)
Note that the add() and sub() methods will modify the value of the object you're calling the method on! This is very untypical for a method that returns a value of its own type. You could misunderstand it that the method would return a new instance with the modified value, but in fact it modifies itself! This is undocumented here. (Only a side note on procedural style mentions it, but it obviously does not apply to object oriented style.)
fortruth at mabang dot net (2010-08-23 23:00:50)
adding 15 min to a datetime
<?php
$initDate = new DateTime("2010/08/24");
$initDate->add(new DateInterval("PT15M"));
echo $initDate->format("Y/m/d m:i:s");//result: 2010/08/24 08:15:00
?>
period:
P1Y2M3DT1H2M3S
period time:
PT1H2M3S