DateTime::modify

date_modify

(PHP 5 >= 5.2.0, PHP 7)

DateTime::modify -- date_modify — Alters the timestamp

Description

Object oriented style

public DateTime DateTime::modify ( string $modify )

Procedural style

DateTime date_modify ( DateTime $object , string $modify )

Alter the timestamp of a DateTime object by incrementing or decrementing in a format accepted by strtotime().

Parameters

object: Procedural style only: A DateTime object returned by date_create(). The function modifies this object.
modify: A date/time string. Valid formats are explained in Date and Time Formats.

Return Values

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

Changelog

Version	Description
5.3.6	Absolute date/time statements now take effect. Previously, only relative parts were used.
5.3.0	Changed the return value on success from `NULL` to DateTime.

Examples

Example #1 DateTime::modify() example

Object oriented style


<?php
$date = new DateTime('2006-12-12');
$date->modify('+1 day');
echo $date->format('Y-m-d');
?>

Procedural style


<?php
$date = date_create('2006-12-12');
date_modify($date, '+1 day');
echo date_format($date, 'Y-m-d');
?>

The above examples will output:

2006-12-13

Example #2 Beware when adding or subtracting months


<?php
$date = new DateTime('2000-12-31');

$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";

$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";
?>

The above example will output:

2001-01-31
2001-03-03

User Contributed Notes

jenspj at msn dot com

4 years ago


These functions makes sure that adding months or years always ends up in the month you would expect.  Works for positive and negative values

<?php
      
       
    $date=new DateTime();
    $date->setDate(2008,2,29);
    
    function addMonths($date,$months){
         
        $init=clone $date;
        $modifier=$months.' months';
        $back_modifier =-$months.' months';
        
        $date->modify($modifier);
        $back_to_init= clone $date;
        $back_to_init->modify($back_modifier);
        
        while($init->format('m')!=$back_to_init->format('m')){
        $date->modify('-1 day')    ;
        $back_to_init= clone $date;
        $back_to_init->modify($back_modifier);    
        }
        
        /*
        if($months<0&&$date->format('m')>$init->format('m'))
        while($date->format('m')-12-$init->format('m')!=$months%12)
        $date->modify('-1 day');
        else
        if($months>0&&$date->format('m')<$init->format('m'))
        while($date->format('m')+12-$init->format('m')!=$months%12)
        $date->modify('-1 day');
        else
        while($date->format('m')-$init->format('m')!=$months%12)
        $date->modify('-1 day');
        */
        
    }
     
    function addYears($date,$years){
        
        $init=clone $date;
        $modifier=$years.' years';
        $date->modify($modifier);
        
        while($date->format('m')!=$init->format('m'))
        $date->modify('-1 day');
        
        
    } 
    
    
    
    addMonths($date,-1);
     addYears($date,3);
    
    
    echo $date->format('F j,Y');
     
 
?>

www dot wesley at gmail dot com

9 months ago


This is an improvement of @jenspj's answer

<?php

$d = new DateTime('2007-12-31');

function addMonths($date, $months)
{
    $years = floor(abs($months / 12));
    $leap = 29 <= $date->format('d');
    $m = 12 * (0 <= $months?1:-1);
    for ($a = 1;$a < $years;++$a) {
        $date = addMonths($date, $m);
    }
    $months -= ($a - 1) * $m;
    
    $init = clone $date;
    if (0 != $months) {
        $modifier = $months . ' months';
        
        $date->modify($modifier);
        if ($date->format('m') % 12 != (12 + $months + $init->format('m')) % 12) {
            $day = $date->format('d');
            $init->modify("-{$day} days");
        }
        $init->modify($modifier);
    }
    
    $y = $init->format('Y');
    if ($leap && ($y % 4) == 0 && ($y % 100) != 0 && 28 == $init->format('d')) {
        $init->modify('+1 day');
    }
    return $init;
}

function addYears($date, $years)
{
    return addMonths($date, 12 * $years);
}

echo $d->format('F j,Y') . ' N<br />';
$d = addMonths($d, +1);
echo $d->format('F j,Y') . ' +1M<br />';
$d = addMonths($d, +1);
echo $d->format('F j,Y') . ' +1M<br />';
$d = addYears($d, +60);
echo $d->format('F j,Y') . ' +60Y<br />';
$d = addYears($d, -59);
echo $d->format('F j,Y') . ' -59Y<br />';

jay dot removethis at grooveshark dot com

2 years ago


Due to DST and the way DateTime internally handles dates, it's possible to get stuck in a time loop.

For example:

<?php
$dt = new DateTime('2012-03-11 3:00AM');
echo $dt->format('YmdH') . "\n";
$dt->modify("-1 hour");
echo $dt->format('YmdH') . "\n";
$dt->modify("-1 hour");
echo $dt->format('YmdH') . "\n";
?>

prints out:

2012031103
2012031103
2012031103

if your timezone is set to America/New_York.

admin at wmfoi dot com dot br

2 years ago


The changelog says: "5.3.0 - Changed the return value on success from NULL to DateTime".

That means that you can't do a Fluid Interface design with it in PHP 5.2.

In other words, this will not work in 5.2:

<?php
$DateTime=new DateTime();
echo $DateTime->modify('+1 day')->format('d');
?>

66Ton99

1 year ago


Extension for DateTime class which solves problem of adding or subtracting months

https://gist.github.com/66Ton99/60571ee49bf1906aaa1c

Jenny jsimonds@atomic jet packs dot com

4 years ago


Note: This method modifies the object in-place. So if you want to calculate a new date but assign the new value to a different object, this will NOT work:

<?php
$numMinutes = 25;
$oDateA = new DateTime('2012-01-01 12:00:00');

print "
Original:<br>
oDateA =  {$oDateA->format('Y-m-d H-i-s')}<br>
";

$oDateB = $oDateA->modify ("+{$numMinutes} minutes");

print "
plus {$numMinutes} minutes:<br>
oDateA =  {$oDateA->format('Y-m-d H-i-s')}<br>
oDateB =  {$oDateB->format('Y-m-d H-i-s')}<br>
";
?>
...produces this:
oDateA = 2012-01-01 12-00-00
plus 25 minutes:
oDateA = 2012-01-01 12-25-00
oDateB = 2012-01-01 12-25-00

Use something like this instead:
<?php
$numMinutes = 25;
$oDateA = new DateTime('2012-01-01 12:00:00');

print "
<p>
Original:<br>
oDateA =  {$oDateA->format('Y-m-d H-i-s')}<br>
";

$oDateB = clone $oDateA;
$oDateB->modify ("+{$numMinutes} minutes");

print "
plus {$numMinutes} minutes:<br>
oDateA =  {$oDateA->format('Y-m-d H-i-s')}<br>
oDateB =  {$oDateB->format('Y-m-d H-i-s')}<br>
";
?>

... produces this:
oDateA = 2012-01-01 12-00-00
plus 25 minutes:
oDateA = 2012-01-01 12-00-00
oDateB = 2012-01-01 12-25-00

Anonymous

1 month ago


I cant believe this is in official PHPDOC, such an incredible retarded bug, and, best of all, No explanation at all... this is the kind of things that make PHPCore developers look like fools.

<?php
$date = new DateTime('2000-12-31');

$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";

$date->modify('+1 month');
echo $date->format('Y-m-d') . "\n";
?>

Result:

2001-01-31
2001-03-03

php at lanar dot com dot au

2 years ago


modify() ignores any timezone information in the data while the DateTime constructor does not.

$dt = new DateTime( '2013-10-26T11:00:00+11:00' ) 
will create a +11 timezone while
$dt->modify( '2013-10-26T11:00:00+02:00' )
does not change the timezone or the time.

<?php
$dt = new DateTime( '2013-10-26T15:00:00Australia/Melbourne' ) ;
echo "\n", $dt->format( "c" ) ;
echo "\nTimezone '", $dt->getTimezone()->getName() . "'." ;
// modify $dt to 1 am new york which is 3 pm melbourne
$dt->modify( '2013-10-26T01:00:00America/New_York' ) ;
// result is 1 am melbourne time, not 3 pm
echo "\n", $dt->format( "c" ) ;
echo "\nTimezone '", $dt->getTimezone()->getName() . "'." ;
?>
Output
2013-10-26T15:00:00+11:00
Timezone 'Australia/Melbourne'.
2013-10-26T01:00:00+11:00
Timezone 'Australia/Melbourne'.

DateTime::modify

date_modify

Description

Parameters

Return Values

Changelog

Examples

See Also

User Contributed Notes