The DateInterval class

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

Introduction

Represents a date interval.

A date interval stores either a fixed amount of time (in years, months, days, hours etc) or a relative time string in the format that DateTimeImmutable's and DateTime's constructors support.

More specifically, the information in an object of the DateInterval class is an instruction to get from one date/time to another date/time. This process is not always reversible.

A common way to create a DateInterval object is by calculating the difference between two date/time objects through DateTimeInterface::diff().

Since there is no well defined way to compare date intervals, DateInterval instances are incomparable.

Class synopsis

class DateInterval {

/* Properties */

public int $y;

public int $m;

public int $d;

public int $h;

public int $i;

public int $s;

public float $f;

public int $invert;

public mixed $days;

public bool $from_string;

public string $date_string;

/* Methods */

public __construct(string $duration)

public static createFromDateString(string $datetime): DateInterval

public format(string $format): string

}

Properties

Warning

The available properties listed below depend on PHP version, and should be considered as readonly.

y: Number of years.
m: Number of months.
d: Number of days.
h: Number of hours.
i: Number of minutes.
s: Number of seconds.
f: Number of microseconds, as a fraction of a second.
invert: Is 1 if the interval represents a negative time period and 0 otherwise. See DateInterval::format().
days: If the DateInterval object was created by DateTimeImmutable::diff() or DateTime::diff(), then this is the total number of full days between the start and end dates. Otherwise, days will be false.
from_string: If the DateInterval object was created by DateInterval::createFromDateString(), then this property's value will be true, and the date_string property will be populated. Otherwise, the value will be false, and the y to f, invert, and days properties will be populated.
date_string: The string used as argument to DateInterval::createFromDateString().

Changelog

Version	Description
8.2.0	The `from_string` and `date_string` properties were added for DateInterval instances that were created using the DateInterval::createFromDateString() method.
8.2.0	Only the `y` to `f`, `invert`, and `days` will be visible.
7.4.0	DateInterval instances are incomparable now; previously, all DateInterval instances were considered equal.
7.1.0	The `f` property was added.

DateInterval::__construct — Creates a new DateInterval object
DateInterval::createFromDateString — Sets up a DateInterval from the relative parts of the string
DateInterval::format — Formats the interval

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User Contributed Notes 4 notes

down

cb ¶

2 years ago

If you want to reverse a date interval use array_reverse and iterator_to_array. I've found using invert to be unreliable.

<?php
$start_date = date_create("2021-01-01");
$end_date   = date_create("2021-01-05"); // If you want to include this date, add 1 day

$interval = DateInterval::createFromDateString('1 day');
$daterange = new DatePeriod($start_date, $interval ,$end_date);

function show_dates ($dr) {
    foreach($dr as $date1){
        echo $date1->format('Y-m-d').'<br>';
    }
}
 
show_dates ($daterange);
   
echo '<br>';

// reverse the array

$daterange = array_reverse(iterator_to_array($daterange));

show_dates ($daterange);
           
?>

Gives 
 2021-01-01
 2021-01-02
 2021-01-03
 2021-01-04

 2021-01-04
 2021-01-03
 2021-01-02
 2021-01-01

down

edgaras at levinson dot lt ¶

6 months ago

There is a handy way to compare intervals by adding them to 0 dates and comparing dates instead

<?php

function compare(DateInterval $first, DateInterval $second): int
{
    $firstDate = (new DateTime())->setTimestamp(0)->add($first);
    $secondDate = (new DateTime())->setTimestamp(0)->add($second);

    return $firstDate <=> $secondDate;
}

echo compare(new DateInterval('P2D'), new DateInterval('PT48H')) . PHP_EOL;
echo compare(DateInterval::createFromDateString('2 days'), DateInterval::createFromDateString('48 hours')) . PHP_EOL;
echo compare(DateInterval::createFromDateString('2 days'), DateInterval::createFromDateString('49 hours')) . PHP_EOL;
echo compare(DateInterval::createFromDateString('2 days'), DateInterval::createFromDateString('47 hours')) . PHP_EOL;

?>

Outputs:
0
0
-1
1

down

julio dot necronomicon at gmail dot com ¶

1 year ago

More simple example i use to add or subtract.

<?php
$Datetime = new Datetime('NOW', new DateTimeZone('America/Bahia'));
$Datetime->add(DateInterval::createFromDateString('2 day'));

echo $Datetime->format("Y-m-d H:i:s");
?>

down

anonymous at nospam dot com ¶

22 days ago

Subtracting months may not work as you might expect. 
Code shows how subtracting 2 months from consecutive days produces potentially unexpected results. 

<?php
$origin = date_create('2025-01-31T00:00:00');
$target = date_create('2024-11-26T00:00:00');

$interval = date_diff($origin, $target);
echo "interval total days: ".$interval->format('%a days');

echo "interval object years: ".$interval->format('%y years');
echo "interval object months: ".$interval->format('%m months');
echo "interval object days: ".$interval->format('%d days');

// create 3 dates that are consecutive, but in two months
$d1 = date_create('2025-01-31T00:00:00');
$d2 = date_create('2025-02-01T00:00:00');
$d3 = date_create('2025-02-02T00:00:00');

// add (negative) interval object to each date
$d1->add($interval);
$d2->add($interval);
$d3->add($interval);

echo "Add (negative) interval object to each date. Non-consecutive results: ";
echo($d1->format("Y-m-d\TH:i:s"));
echo($d2->format("Y-m-d\TH:i:s"));
echo($d3->format("Y-m-d\TH:i:s"));

// reset dates
$d1 = date_create('2025-01-31T00:00:00');
$d2 = date_create('2025-02-01T00:00:00');
$d3 = date_create('2025-02-02T00:00:00');

// Use same dates, but subtract total number of days instead of adding interval object: ";
$d1->sub(new DateInterval('P'.$interval->format('%a').'D'));
$d2->sub(new DateInterval('P'.$interval->format('%a').'D'));
$d3->sub(new DateInterval('P'.$interval->format('%a').'D'));

echo "Use same dates, but subtract total number of days instead of adding interval object. Results (consecutive): ";
echo($d1->format("Y-m-d\TH:i:s"));
echo($d2->format("Y-m-d\TH:i:s"));
echo($d3->format("Y-m-d\TH:i:s"));

$d1 = date_create('2025-01-31T00:00:00');
$d2 = date_create('2025-02-01T00:00:00');
$d3 = date_create('2025-02-02T00:00:00');

// do month separately for 2025-02-01T00:00:00
echo "Do month separately (interesting): ";

echo ('Subtract '. $interval->format('%m').' months (might not expect this):');
echo ('Jan 31 - 2 months (61 days = Dec, 31 days + Nov, 30 days) ==> Dec 1');
echo ('Feb 1  - 2 months (62 days = Dec, 31 days + Jan, 31 days) ==> Dec 1');
$d1->sub(new DateInterval('P'.$interval->format('%m').'M'));
echo $d1->format("Y-m-d\TH:i:s");
$d2->sub(new DateInterval('P'.$interval->format('%m').'M'));
echo $d2->format("Y-m-d\TH:i:s");
$d3->sub(new DateInterval('P'.$interval->format('%m').'M'));
echo $d3->format("Y-m-d\TH:i:s");
?>

Output: 

interval total days: 66 days
interval object years: 0 years
interval object months: 2 months
interval object days: 5 days

create 3 dates that are consecutive, but in two months:
$d1 = 2025-01-31T00:00:00
$d2 = 2025-02-01T00:00:00
$d3 = 2025-02-02T00:00:00

Add (negative) interval object to each date. Non-consecutive results:
2024-11-26T00:00:00
2024-11-26T00:00:00
2024-11-27T00:00:00

Use same dates, but subtract total number of days instead of adding interval object. Results (consecutive):
2024-11-26T00:00:00
2024-11-27T00:00:00
2024-11-28T00:00:00

Do month separately (interesting):

Subtract 2 months (might not expect this):
Jan 31 - 2 months (61 days = Dec, 31 days + Nov, 30 days) ==> Dec 1
Feb 1 - 2 months (62 days = Dec, 31 days + Jan, 31 days) ==> Dec 1
2024-12-01T00:00:00
2024-12-01T00:00:00
2024-12-02T00:00:00

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The DateInterval class

Introduction

Class synopsis

Properties

Changelog

Table of Contents

Found A Problem?

User Contributed Notes 4 notes