DateTime::modify

date_modify

(PHP 5 >= 5.2.0, PHP 7)

DateTime::modify -- date_modify — Alters the timestamp

说明

面向对象风格

public DateTime DateTime::modify ( string $modify )

过程化风格

DateTime date_modify ( DateTime $object , string $modify )

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

参数

object: 仅过程化风格：由 date_create() 返回的 DateTime 类型的对象。此函数会修改这个对象。
modify: 日期/时间字符串。正确格式的说明详见日期与时间格式。

返回值

返回被修改的 DateTime 对象，或者在失败时返回 FALSE.

更新日志

版本	说明
5.3.6	Absolute date/time statements now take effect. Previously, only relative parts were used.
5.3.0	将返回值从`NULL`改为 DateTime 类型。

范例

Example #1 DateTime::modify() example

面向对象风格


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

过程化风格


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

以上例程会输出：

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";
?>

以上例程会输出：

2001-01-31
2001-03-03

参见

strtotime() - 将任何字符串的日期时间描述解析为 Unix 时间戳
DateTime::add() - Adds an amount of days, months, years, hours, minutes and seconds to a DateTime object
DateTime::sub() - Subtracts an amount of days, months, years, hours, minutes and seconds from a DateTime object
DateTime::setDate() - Sets the date
DateTime::setISODate() - Sets the ISO date
DateTime::setTime() - Sets the time
DateTime::setTimestamp() - Sets the date and time based on an Unix timestamp

User Contributed Notes

mangotonk at gmail dot com 24-Jan-2017 02:55


a slightly more compact way of getting the month shift



<?php



      /**

     * correctly calculates end of months when we shift to a shorter or longer month

     * workaround for http://php.net/manual/en/datetime.add.php#example-2489 

     * 

     * Makes the assumption that shifting from the 28th Feb +1 month is 31st March

     * Makes the assumption that shifting from the 28th Feb -1 month is 31st Jan

     * Makes the assumption that shifting from the 29,30,31 Jan +1 month is 28th (or 29th) Feb

     *

     * 

     * @param DateTime $aDate

     * @param int $months positive or negative

     * 

     * @return DateTime new instance - original parameter is unchanged

     */



    function MonthShifter (DateTime $aDate,$months){

        $dateA = clone($aDate);

        $dateB = clone($aDate);

        $plusMonths = clone($dateA->modify($months . ' Month'));

        //check whether reversing the month addition gives us the original day back

        if($dateB != $dateA->modify($months*-1 . ' Month')){ 

            $result = $plusMonths->modify('last day of last month');

        } elseif($aDate == $dateB->modify('last day of this month')){

            $result =  $plusMonths->modify('last day of this month');

        } else {

            $result = $plusMonths;

        }

        return $result;

    }



//TEST



$x = new DateTime('2017-01-30');

echo( $x->format('Y-m-d')." past end of feb, but not dec<br>");

echo('b ' . MonthShifter($x,1)->format(('Y-m-d'))."<br>");

echo('c ' . MonthShifter($x,-1)->format(('Y-m-d'))."<br>");



$x = new DateTime('2017-01-15');

echo("<br>" . $x->format('Y-m-d')." middle of the month <br>");

echo('d ' . MonthShifter($x,1)->format(('Y-m-d'))."<br>");

echo('e ' . MonthShifter($x,-1)->format(('Y-m-d'))."<br>");



$x = new DateTime('2017-02-28');

echo("<br>" . $x->format('Y-m-d')." end of Feb<br>");

echo('f ' . MonthShifter($x,1)->format(('Y-m-d'))."<br>");

echo('g ' . MonthShifter($x,-1)->format(('Y-m-d'))."<br>");



$x = new DateTime('2017-01-31');

echo("<br>" .  $x->format('Y-m-d')." end of Jan<br>");

echo('h ' . MonthShifter($x,1)->format(('Y-m-d'))."<br>");

echo('i ' . MonthShifter($x,-1)->format(('Y-m-d'))."<br>");



$x = new DateTime('2017-01-31');

echo("<br>" .  $x->format('Y-m-d')." end of Jan +/- 1 years diff, leap year respected<br>");

echo('j ' . MonthShifter($x,13)->format(('Y-m-d'))."<br>");

echo('k ' . MonthShifter($x,-11)->format(('Y-m-d'))."<br>");



//returns



2017-01-30 past end of feb, but not dec

b 2017-02-28

c 2016-12-30



2017-01-15 middle of the month 

d 2017-02-15

e 2016-12-15



2017-02-28end of Feb

f 2017-03-31

g 2017-01-31



2017-01-31end of Jan

h 2017-02-28

i 2016-12-31



2017-01-31end of Jan +/- 1 years diff, leap year respected

j 2018-02-28

k 2016-02-29

sinus at sinpi dot net 30-Nov-2016 07:54


A very simple way to ensure we do not cross over month boundaries when adding months is to just go back a few days if the day number got reset:



<?php

function addMonths($date,$months) {

  $orig_day = $date->format("d");

  $date->modify("+".$months." months");

  while ($date->format("d")<$orig_day && $date->format("d")<5) {

    $date->modify("-1 day");

  }

}



for ($i=0;$i<5;$i++) {

  $d = new DateTime("2000-01-10");

  addmonths($d,$i);

  echo $d->format("Y-m-d")."<br>";

}

for ($i=0;$i<5;$i++) {

  $d = new DateTime("2000-01-31");

  addmonths($d,$i);

  echo $d->format("Y-m-d")."<br>";

}

?>



prints:

2000-01-10

2000-02-10

2000-03-10

2000-04-10

2000-05-10

2000-01-31

2000-02-29

2000-03-31

2000-04-30

2000-05-31

Anonymous 31-Mar-2016 12:14


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

www dot wesley at gmail dot com 05-Jul-2015 05:31


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 />';

66Ton99 14-May-2014 12:31


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



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

admin at wmfoi dot com dot br 09-Apr-2014 05:22


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');

?>

jay dot removethis at grooveshark dot com 29-Oct-2013 02:46


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.

php at lanar dot com dot au 26-Oct-2013 03:50


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'.

Jenny jsimonds@atomic jet packs dot com 16-Apr-2012 06:04


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

jenspj at msn dot com 20-Feb-2012 11:34


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');

     

 

?>