(PHP 5 >= 5.2.0)
DateTime::modify -- date_modify — Alters the timestamp
面向对象风格
过程化风格
Alter the timestamp of a DateTime object by incrementing or decrementing in a format accepted by strtotime().
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。
返回被修改的 DateTime 对象， 或者在失败时返回 FALSE.
| 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。 |
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
Jenny jsimonds@atomic jet packs dot com (2012-04-15 21:04:34)
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 (2012-02-20 14:34:55)
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');
?>
tom at r dot je (2009-06-18 07:43:32)
If you want to find the next working day (assuming mon-fri) you can use this:
<?php
$d = new DateTime();
$day = $d->format('w');
if ($day == 0 || $day >= 5) $d->modify('+' . ((7-$day+1) % 7) . ' days');
else $d->modify('+1 day');
?>