DateTime::add

(PHP 5 >= 5.3.0, PHP 7)

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

public DateTime DateTime::add ( DateInterval $interval )

Object oriented style

Procedural style

DateTime date_add ( DateTime $object , DateInterval $interval )

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

Returns:

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

Examples:

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

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

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