PHP 5.5.15 is released

DateTime::add

date_add

(PHP 5 >= 5.3.0)

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 DateTime::add ( DateInterval $interval )

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

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
$date 
date_create('2000-01-01');
date_add($datedate_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.

See Also

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User Contributed Notes 4 notes

up
25
Anonymous
3 years ago
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.)
up
7
glavic at gmail dot com
10 months ago
If you need add() and sub() that don't modify object values, you can create new methods like this:

<?php

class DateTimeEnhanced extends DateTime {

    public function
returnAdd(DateInterval $interval)
    {
       
$dt = clone $this;
       
$dt->add($interval);
        return
$dt;
    }
   
    public function
returnSub(DateInterval $interval)
    {
       
$dt = clone $this;
       
$dt->sub($interval);
        return
$dt;
    }

}

$interval = DateInterval::createfromdatestring('+1 day');

$dt = new DateTimeEnhanced; # initialize new object
echo $dt->format(DateTime::W3C) . "\n"; # 2013-09-12T15:01:44+02:00

$dt->add($interval); # this modifies the object values
echo $dt->format(DateTime::W3C) . "\n"; # 2013-09-13T15:01:44+02:00

$dtNew = $dt->returnAdd($interval); # this returns the new modified object and doesn't change original object
echo $dt->format(DateTime::W3C) . "\n"; # 2013-09-13T15:01:44+02:00
echo $dtNew->format(DateTime::W3C) . "\n"; # 2013-09-14T15:01:44+02:00
up
2
artaxerxes2 at iname dot com
10 months ago
Be careful that the internal timer to your DateTime object can be changed drastically when adding even 1 second, during the switch from DST to normal.
Consider the following:
<?php

$ts
= 1383458399; /* 2013-11-03 01:59:59 in Eastern Saving Time */
$dst = DateTime::createFromFormat('U',$ts, new DateTimeZone('GMT')); /* timezone is ignored for a unix timestamp, but if we don't put it, php throws warnings */
$dst->setTimeZone(new DateTimeZone('EST5EDT')); /* a timezone effectuating the change */
$second = new DateInterval('PT1S'); /* one second */

echo $ts . "\t" . $dst->format("U\tY-m-d H:i:s T") . "\n";

$dst->add($second);
$ts++;

echo
$ts . "\t" . $dst->format("U\tY-m-d H:i:s T") . "\n";

/* results:
1383458399    1383458399    2013-11-03 01:59:59 EDT
1383458400    1383462000    2013-11-03 02:00:00 EST

noticed how the second column went from 1383458399 to 1383462000 even though only 1 second was added?
*/

?>
up
-3
fortruth at mabang dot net
3 years ago
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
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