(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
Object oriented style
Procedural style
Adds the specified DateInterval object to the specified DateTime object.
objectProcedural style only: A DateTime object returned by date_create(). The function modifies this object.
interval
A DateInterval object
Returns the DateTime object for method chaining or FALSE on failure.
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
DateTime::modify() is an alternative when using PHP 5.2.
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.)
If you're using PHP >= 5.5, instead of using "glavic at gmail dot com"'s DateTimeEnhanced class, use the built in DateTimeImmutable type. When you call DateTimeImmutable::add() it will return a new object, rather than modifying the original
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 $dtNew->format(DateTime::W3C) . "\n"; # 2013-09-14T15:01:44+02:00
Here is a solution to adding months when you want 2014-10-31 to become 2014-11-30 instead of 2014-12-01.
<?php
/**
* Class MyDateTime
*
* Extends DateTime to include a sensible addMonth method.
*
* This class provides a method that will increment the month, and
* if the day is greater than the last day in the new month, it
* changes the day to the last day of that month. For example,
* If you add one month to 2014-10-31 using DateTime::add, the
* result is 2014-12-01. Using MyDateTime::addMonth the result is
* 2014-11-30.
*/
class MyDateTime extends DateTime
{
public function addMonth($num = 1)
{
$date = $this->format('Y-n-j');
list($y, $m, $d) = explode('-', $date);
$m += $num;
while ($m > 12)
{
$m -= 12;
$y++;
}
$last_day = date('t', strtotime("$y-$m-1"));
if ($d > $last_day)
{
$d = $last_day;
}
$this->setDate($y, $m, $d);
}
}
?>
Another simple solution to adding a month but not autocorrecting days to the next month is this.
(Also works for substracting months)
$dt = new DateTime("2016-01-31");
$oldDay = $dt->format("d");
$dt->add(new DateInterval("P1M")); // 2016-03-02
$newDay = $dt->format("d");
if($oldDay != $newDay) {
// Check if the day is changed, if so we skipped to the next month.
// Substract days to go back to the last day of previous month.
$dt->sub(new DateInterval("P" . $newDay . "D"));
}
echo $dt->format("Y-m-d"); // 2016-02-29
Hope this helps someone.
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" . $dst->format("U\tY-m-d H:i:s T") . "\n";
/* results:
1383458399 1383458399 2013-11-03 01:59:59 EDT
1383458400 1383462000 2013-11-03 02:00:00 EST
noticed how the second column went from 1383458399 to 1383462000 even though only 1 second was added?
*/
?>
Be careful when using this function, I may have happened upon a bug in PHP7.
My code is as follows
//get date from post or else fill with today's date
if (isset($_POST["from"]))
{
$from = date_create($_POST["from"]);
}else{
$from = date_create(date("Y-m-d"));
}
//get date from post if there isn't one just take the same date as what is in the $from variable and add one day to it
if (isset($_POST["to"]))
{
$to = date_create($_POST["to"]);
}else{
$to = $from;
date_modify($to, '+1 day');
}
echo(date_format($from, 'Y-m-d') . " " . date_format($to, 'Y-m-d'));
The resultant output is
$from = 2015-12-11
$to = 2015-12-11
In actuality the result should be
$from = 2015-12-10
$to = 2015-12-11
For some reason the code above modifies the $from variable in the line date_modify($to, '+1 day'); even though it shouldn't as the $from variable isn't being modified.
to fix this i needed to change the code to
//get date from post or else fill with today's date
if (isset($_POST["from"]))
{
$from = date_create($_POST["from"]);
}else{
$from = date_create(date("Y-m-d"));
}
//get date from post if there isn't one just take the same date as what is in the $from variable and add one day to it
if (isset($_POST["to"]))
{
$to = date_create($_POST["to"]);
}else{
$to = date_create(date("Y-m-d"));
date_modify($to, '+1 day');
}
echo(date_format($from, 'Y-m-d') . " " . date_format($to, 'Y-m-d'));
This isn't strictly the code I wanted. Possible bug?
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
