The DateTimeInterface interface

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

Introduction

DateTimeInterface was created so that parameter, return, or property type declarations may accept either DateTimeImmutable or DateTime as a value. It is not possible to implement this interface with userland classes.

Common constants that allow for formatting DateTimeImmutable or DateTime objects through DateTimeImmutable::format() and DateTime::format() are also defined on this interface.

Interface synopsis

interface DateTimeInterface {

/* Constants */

public const string ATOM = "Y-m-d\\TH:i:sP";

public const string COOKIE = "l, d-M-Y H:i:s T";

public const string ISO8601 = "Y-m-d\\TH:i:sO";

public const string ISO8601_EXPANDED = "X-m-d\\TH:i:sP";

public const string RFC822 = "D, d M y H:i:s O";

public const string RFC850 = "l, d-M-y H:i:s T";

public const string RFC1036 = "D, d M y H:i:s O";

public const string RFC1123 = "D, d M Y H:i:s O";

public const string RFC7231 = "D, d M Y H:i:s \\G\\M\\T";

public const string RFC2822 = "D, d M Y H:i:s O";

public const string RFC3339 = "Y-m-d\\TH:i:sP";

public const string RFC3339_EXTENDED = "Y-m-d\\TH:i:s.vP";

public const string RSS = "D, d M Y H:i:s O";

public const string W3C = "Y-m-d\\TH:i:sP";

/* Methods */

public diff(DateTimeInterface $targetObject, bool $absolute = false): DateInterval

public format(string $format): string

public getOffset(): int

public getTimestamp(): int

public getTimezone(): DateTimeZone|false

public __wakeup(): void

}

Predefined Constants

DateTimeInterface::ATOM
DATE_ATOM: Atom (example: 2005-08-15T15:52:01+00:00)
DateTimeInterface::COOKIE
DATE_COOKIE: HTTP Cookies (example: Monday, 15-Aug-2005 15:52:01 UTC)
DateTimeInterface::ISO8601
DATE_ISO8601: ISO-8601 (example: 2005-08-15T15:52:01+0000)
Note: This format is not compatible with ISO-8601, but is left this way for backward compatibility reasons. Use DateTimeInterface::ISO8601_EXPANDED, DateTimeInterface::ATOM for compatibility with ISO-8601 instead. (ref ISO8601:2004 section 4.3.3 clause d)
DateTimeInterface::ISO8601_EXPANDED
DATE_ISO8601_EXPANDED: ISO-8601 Expanded (example: +10191-07-26T08:59:52+01:00)
Note: This format allows for year ranges outside of ISO-8601's normal range of 0000-9999 by always including a sign character. It also addresses that that timezone part (+01:00) is compatible with ISO-8601.
DateTimeInterface::RFC822
DATE_RFC822: RFC 822 (example: Mon, 15 Aug 05 15:52:01 +0000)
DateTimeInterface::RFC850
DATE_RFC850: RFC 850 (example: Monday, 15-Aug-05 15:52:01 UTC)
DateTimeInterface::RFC1036
DATE_RFC1036: RFC 1036 (example: Mon, 15 Aug 05 15:52:01 +0000)
DateTimeInterface::RFC1123
DATE_RFC1123: RFC 1123 (example: Mon, 15 Aug 2005 15:52:01 +0000)
DateTimeInterface::RFC7231
DATE_RFC7231: RFC 7231 (since PHP 7.0.19 and 7.1.5) (example: Sat, 30 Apr 2016 17:52:13 GMT)
DateTimeInterface::RFC2822
DATE_RFC2822: RFC 2822 (example: Mon, 15 Aug 2005 15:52:01 +0000)
DateTimeInterface::RFC3339
DATE_RFC3339: Same as DATE_ATOM
DateTimeInterface::RFC3339_EXTENDED
DATE_RFC3339_EXTENDED: RFC 3339 EXTENDED format (example: 2005-08-15T15:52:01.000+00:00)
DateTimeInterface::RSS
DATE_RSS: RSS (example: Mon, 15 Aug 2005 15:52:01 +0000)
DateTimeInterface::W3C
DATE_W3C: World Wide Web Consortium (example: 2005-08-15T15:52:01+00:00)

Changelog

Version	Description
8.2.0	The constant `DateTimeInterface::ISO8601_EXPANDED` was added.
7.2.0	The class constants of DateTime are now defined on DateTimeInterface.

DateTimeInterface::diff — Returns the difference between two DateTime objects
DateTimeInterface::format — Returns date formatted according to given format
DateTimeInterface::getOffset — Returns the timezone offset
DateTimeInterface::getTimestamp — Gets the Unix timestamp
DateTimeInterface::getTimezone — Return time zone relative to given DateTime
DateTime::__wakeup — The __wakeup handler

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User Contributed Notes 1 note

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bohwaz ¶

1 year ago

Please note that if you are using DATE_RFC7231 format (used in HTTP/1.1), you'll need to change the DateTime object timezone to GMT *before*, or you'll encounter weird results, as this format DOES NOT convert the date to GMT.

So if you have a DateTime object using UTC+01:00 as its timezone, you will get a difference of 1 hour between your resulting date string and what should be the "correct" date.

Recommended use:

<?php
$date_gmt = clone $date;
$date_gmt->setTimezone(new \DateTimeZone('GMT'));
echo $date_gmt->format(DATE_RFC7231);
?>