PHP Manual
DateTime
Adds an amount of days, months, years, hours, minutes and seconds to a DateTime object

DateTime::add

date_add

(PHP 5 >= 5.3.0, PHP 7)

DateTime::add -- date_add — Adds an amount of days, months, years, hours, minutes and seconds to a DateTime object

Description

Object oriented style

public DateTime::add ( DateInterval $interval ) : DateTime

Procedural style

date_add ( DateTime $object , DateInterval $interval ) : DateTime

Adds the specified DateInterval object to the specified DateTime object.

Parameters

object: Procedural style only: A DateTime object returned by date_create(). The function modifies this object.
interval: A DateInterval object

Return Values

Returns the DateTime object for method chaining or FALSE on failure.

Examples

Example #1 DateTime::add() example

Object oriented style

<?php$date = new DateTime('2000-01-01');$date->add(new DateInterval('P10D'));echo $date->format('Y-m-d') . "\n";?>

Procedural style

<?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');?>

The above examples will output:

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";?>

The above example will output:

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";?>

The above example will output:

2001-01-31
2001-03-03

Notes

DateTime::modify() is an alternative when using PHP 5.2.

Php/docs/datetime.add

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