DateInterval::__construct

(PHP 5 >= 5.3.0, PHP 7)

DateInterval::__construct — Creates a new DateInterval object

说明

public DateInterval::__construct ( string $interval_spec )

Creates a new DateInterval object.

参数

interval_spec

An interval specification.

The format starts with the letter P, for period. Each duration period is represented by an integer value followed by a period designator. If the duration contains time elements, that portion of the specification is preceded by the letter T.

**`interval_spec` Period Designators**
Period Designator	Description
Y	years
M	months
D	days
W	weeks. These get converted into days, so can not be combined with D.
H	hours
M	minutes
S	seconds

Here are some simple examples. Two days is P2D. Two seconds is PT2S. Six years and five minutes is P6YT5M.

Note:
The unit types must be entered from the largest scale unit on the left to the smallest scale unit on the right. So years before months, months before days, days before minutes, etc. Thus one year and four days must be represented as P1Y4D, not P4D1Y.

The specification can also be represented as a date time. A sample of one year and four days would be P0001-00-04T00:00:00. But the values in this format can not exceed a given period's roll-over-point (e.g. 25 hours is invalid).

These formats are based on the » ISO 8601 duration specification.

错误／异常

Throws an Exception when the interval_spec cannot be parsed as an interval.

范例

Example #1 DateInterval example


<?php

$interval = new DateInterval('P2Y4DT6H8M');
var_dump($interval);

?>

以上例程会输出：

object(DateInterval)#1 (8) {
  ["y"]=>
  int(2)
  ["m"]=>
  int(0)
  ["d"]=>
  int(4)
  ["h"]=>
  int(6)
  ["i"]=>
  int(8)
  ["s"]=>
  int(0)
  ["invert"]=>
  int(0)
  ["days"]=>
  bool(false)
}

参见

DateInterval::format() - Formats the interval
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::diff() - Returns the difference between two DateTime objects

User Contributed Notes

Hernanibus 22-Sep-2017 05:03


It is not stated, but you cannot create directly a negative interval, this is you cannot create a "-2 days" interval as:



<?

$interval = new DateInterval("P-2D");//or

$interval = new DateInterval("-P2D");

?>



Instead you have to create first the interval and then set its 'invert' property to 1, this is:



<?

$interval = new DateInterval("P2D");

$interval->invert = 1;

?>



Then you should keep in mind that this interval acts as a negative number, hence to subtract the interval from a given date you must 'add' it:



<?

$interval = new DateInterval("P2D");

$interval->invert = 1;

$date       = new DateTime ("1978-01-23 17:46:00");

$date->add($interval)->format("Y-m-d H:i:s");//this is "1978-01-21 17:46:00"

?>

Ray.Paseur sometimes uses Gmail 29-Apr-2016 01:47


To recover the interval specification string:



<?php

function get_interval_spec(DateTime $alpha, DateTime $omega)

{

    $intvl = $alpha->diff($omega);



    $date = NULL;

    if ($intvl->y) $date .= $intvl->y . 'Y';

    if ($intvl->m) $date .= $intvl->m . 'M';

    if ($intvl->d) $date .= $intvl->d . 'D';



    $time = NULL;

    if ($intvl->h) $time .= $intvl->h . 'H';

    if ($intvl->i) $time .= $intvl->i . 'M';

    if ($intvl->s) $time .= $intvl->s . 'S';

    if ($time) $time = 'T' . $time;



    $text ='P' . $date . $time;

    if ($text == 'P') return 'PT0S';

    return $text;

}

lsloan-php dot net at umich dot edu 11-Mar-2016 07:05


Although PHP refers to periods of time as "intervals", ISO 8601 refers to them as "durations".  In ISO 8601, "intervals" are something else.



While ISO 8601 allows fractions for all parts of a duration (e.g., "P0.5Y"), DateInterval does not.  Use caution when calculating durations.  If the duration has a fractional part, it may be lost when storing it in a DateInterval object.

userexamplecom at mailinator dot com 05-Feb-2016 10:49


Take care, if you have a DateTime Object on the 31h of January and add Da DateInterval of one Month, then you are in March instead of February.



For Example:

---

// given the actual date is 2017-01-31

$today = new DateTime('now', $timeZoneObject);

$today->add(new DateInterval('P1M'));

echo $today->format('m');

// output: 03

---

admin at torntech dot com 23-Feb-2015 06:22


Warning - despite the $interval_spec accepting the ISO 8601 specification format, it does not accept decimal fraction values with period or comma as stated in the specification.



https://bugs.php.net/bug.php?id=53831



<?php

/* Example from ISO 8601 documentation */

$interval = new DateInterval('P0.5Y');

?>



Will result in

Fatal error: Uncaught exception 'Exception' with message 'DateInterval::__construct(): Unknown or bad format (P0.5Y)'

bkilinc at deyta dot net 21-Dec-2013 12:28


interval_spec Period Designators, has two 'M's for months and minutes.

owen at beliefs.com 12-Jul-2013 12:20


M is used to indicate both months and minutes.



As noted on the referenced wikipedia page for ISO 6801 http://en.wikipedia.org/wiki/Iso8601#Durations



To resolve ambiguity, "P1M" is a one-month duration and "PT1M" is a one-minute duration (note the time designator, T, that precedes the time value).



Using: PHP 5.3.2-1ubuntu4.19



// For 3 Months

$dateTime = new DateTime;echo $dateTime->format( DateTime::ISO8601 ), PHP_EOL;

$dateTime->add(new DateInterval("P3M"));

echo $dateTime->format( DateTime::ISO8601 ), PHP_EOL;

Results in:

2013-07-11T11:12:26-0400

2013-10-11T11:12:26-0400



// For 3 Minutes

$dateTime = new DateTime;echo $dateTime->format( DateTime::ISO8601 ), PHP_EOL;

$dateTime->add(new DateInterval("PT3M"));

echo $dateTime->format( DateTime::ISO8601 ), PHP_EOL;

Results in:

2013-07-11T11:12:42-0400

2013-07-11T11:15:42-0400



Insert a T after the P in the interval to add 3 minutes instead of 3 months.

buvinghausen at gmail dot com 10-Apr-2012 03:50


I think it is easiest if you would just use the sub method on the DateTime class.



<?php

$date = new DateTime();

$date->sub(new DateInterval("P89D"));

daniellehr at gmx dot de 21-Mar-2012 10:06


Alternatively you can use DateInterval::createFromDateString() for negative intervals:



<?php

$date = new DateTime();

$date->add(DateInterval::createFromDateString('-89 days'));

jawzx01 at gmail dot com 22-Feb-2012 07:43


As previously mentioned, to do a negative DateInterval object, you'd code: 





<?php


$date1 = new DateTime();


$eightynine_days_ago = new DateInterval( "P89D" );


$eightynine_days_ago->invert = 1; //Make it negative. 


$date1->add( $eightynine_days_ago );


?>





and then $date1 is now 89 days in the past.

kevinpeno at gmail dot com 17-Mar-2011 08:47


Note that, while a DateInterval object has an $invert property, you cannot supply a negative directly to the constructor similar to specifying a negative in XSD ("-P1Y"). You will get an exception through if you do this. 



Instead you need to construct using a positive interval ("P1Y") and the specify the $invert property === 1.

kuzb 05-Feb-2011 01:42


It should be noted that this class will not calculate days/hours/minutes/seconds etc given a value in a single denomination of time.  For example:



<?php

    $di = new DateInterval('PT3600S');

    echo $di->format('%H:%i:%s');

    

?>



will yield 0:0:3600 instead of the expected 1:0:0