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<title>The DateTimeInterface interface</title>
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<h1 class="title">The DateTimeInterface interface</h1>
<div class="partintro"><p class="verinfo">(PHP 5 >= 5.5.0, PHP 7)</p>
<div class="section" id="datetimeinterface.intro">
<h2 class="title">Introduction</h2>
<p class="para">
DateTimeInterface is meant so that both DateTime and DateTimeImmutable can
be type hinted for. It is not possible to implement this interface with
userland classes.
</p>
</div>
<div class="section" id="datetimeinterface.synopsis">
<h2 class="title">Class synopsis</h2>
<div class="classsynopsis">
<div class="ooclass"></div>
<div class="classsynopsisinfo">
<span class="ooclass">
<strong class="classname">DateTimeInterface</strong>
</span>
{</div>
<div class="classsynopsisinfo classsynopsisinfo_comment">/* Constants */</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.atom"><var class="varname">ATOM</var></a></var>
<span class="initializer"> = "Y-m-d\TH:i:sP"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.cookie"><var class="varname">COOKIE</var></a></var>
<span class="initializer"> = "l, d-M-Y H:i:s T"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.iso8601"><var class="varname">ISO8601</var></a></var>
<span class="initializer"> = "Y-m-d\TH:i:sO"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rfc822"><var class="varname">RFC822</var></a></var>
<span class="initializer"> = "D, d M y H:i:s O"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rfc850"><var class="varname">RFC850</var></a></var>
<span class="initializer"> = "l, d-M-y H:i:s T"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rfc1036"><var class="varname">RFC1036</var></a></var>
<span class="initializer"> = "D, d M y H:i:s O"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rfc1123"><var class="varname">RFC1123</var></a></var>
<span class="initializer"> = "D, d M Y H:i:s O"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rfc2822"><var class="varname">RFC2822</var></a></var>
<span class="initializer"> = "D, d M Y H:i:s O"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rfc3339"><var class="varname">RFC3339</var></a></var>
<span class="initializer"> = "Y-m-d\TH:i:sP"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rfc3339_extended"><var class="varname">RFC3339_EXTENDED</var></a></var>
<span class="initializer"> = "Y-m-d\TH:i:s.vP"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.rss"><var class="varname">RSS</var></a></var>
<span class="initializer"> = "D, d M Y H:i:s O"</span>
;</div>
<div class="fieldsynopsis">
<span class="modifier">const</span>
<span class="type">string</span>
<var class="fieldsynopsis_varname"><a href="class.datetimeinterface.html#datetime.constants.w3c"><var class="varname">W3C</var></a></var>
<span class="initializer"> = "Y-m-d\TH:i:sP"</span>
;</div>
<div class="classsynopsisinfo classsynopsisinfo_comment">/* Methods */</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">DateInterval</span> <span class="methodname"><a href="datetime.diff.html" class="methodname">diff</a></span>
( <span class="methodparam"><span class="type"><a href="class.datetimeinterface.html" class="type DateTimeInterface">DateTimeInterface</a></span> <code class="parameter">$datetime2</code></span>
[, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$absolute</code><span class="initializer"> = <strong><code>FALSE</code></strong></span></span>
] )</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">string</span> <span class="methodname"><a href="datetime.format.html" class="methodname">format</a></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$format</code></span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">int</span> <span class="methodname"><a href="datetime.getoffset.html" class="methodname">getOffset</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">int</span> <span class="methodname"><a href="datetime.gettimestamp.html" class="methodname">getTimestamp</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">DateTimeZone</span> <span class="methodname"><a href="datetime.gettimezone.html" class="methodname">getTimezone</a></span>
( <span class="methodparam">void</span>
)</div>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="methodname"><a href="datetime.wakeup.html" class="methodname">__wakeup</a></span>
( <span class="methodparam">void</span>
)</div>
}</div>
</div>
<div class="section" id="datetime.constants.types">
<h2 class="title">Predefined Constants</h2>
<dl>
<dt id="datetime.constants.atom"><strong><code>DateTimeInterface::ATOM</code></strong></dt>
<dt>
<strong><code>DATE_ATOM</code></strong></dt>
<dd>
<span class="simpara">
Atom (example: 2005-08-15T15:52:01+00:00)
</span>
</dd>
<dt id="datetime.constants.cookie"><strong><code>DateTimeInterface::COOKIE</code></strong></dt>
<dt>
<strong><code>DATE_COOKIE</code></strong></dt>
<dd>
<span class="simpara">
HTTP Cookies (example: Monday, 15-Aug-2005 15:52:01 UTC)
</span>
</dd>
<dt id="datetime.constants.iso8601"><strong><code>DateTimeInterface::ISO8601</code></strong></dt>
<dt>
<strong><code>DATE_ISO8601</code></strong></dt>
<dd>
<span class="simpara">
ISO-8601 (example: 2005-08-15T15:52:01+0000)
</span>
<blockquote class="note"><p><strong class="note">Note</strong>:
<span class="simpara">
This format is not compatible with ISO-8601, but is left this way for
backward compatibility reasons. Use <strong><code>DateTime::ATOM</code></strong>
or <strong><code>DATE_ATOM</code></strong> for compatibility with ISO-8601
instead.
</span>
</p></blockquote>
</dd>
<dt id="datetime.constants.rfc822"><strong><code>DateTimeInterface::RFC822</code></strong></dt>
<dt>
<strong><code>DATE_RFC822</code></strong></dt>
<dd>
<span class="simpara">
RFC 822 (example: Mon, 15 Aug 05 15:52:01 +0000)
</span>
</dd>
<dt id="datetime.constants.rfc850"><strong><code>DateTimeInterface::RFC850</code></strong></dt>
<dt>
<strong><code>DATE_RFC850</code></strong></dt>
<dd>
<span class="simpara">
RFC 850 (example: Monday, 15-Aug-05 15:52:01 UTC)
</span>
</dd>
<dt id="datetime.constants.rfc1036"><strong><code>DateTimeInterface::RFC1036</code></strong></dt>
<dt>
<strong><code>DATE_RFC1036</code></strong></dt>
<dd>
<span class="simpara">
RFC 1036 (example: Mon, 15 Aug 05 15:52:01 +0000)
</span>
</dd>
<dt id="datetime.constants.rfc1123"><strong><code>DateTimeInterface::RFC1123</code></strong></dt>
<dt>
<strong><code>DATE_RFC1123</code></strong></dt>
<dd>
<span class="simpara">
RFC 1123 (example: Mon, 15 Aug 2005 15:52:01 +0000)
</span>
</dd>
<dt id="datetime.constants.rfc2822"><strong><code>DateTimeInterface::RFC2822</code></strong></dt>
<dt>
<strong><code>DATE_RFC2822</code></strong></dt>
<dd>
<span class="simpara">
RFC 2822 (example: Mon, 15 Aug 2005 15:52:01 +0000)
</span>
</dd>
<dt id="datetime.constants.rfc3339"><strong><code>DateTimeInterface::RFC3339</code></strong></dt>
<dt>
<strong><code>DATE_RFC3339</code></strong></dt>
<dd>
<span class="simpara">
Same as <strong><code>DATE_ATOM</code></strong> (since PHP 5.1.3)
</span>
</dd>
<dt id="datetime.constants.rfc3339_extended"><strong><code>DateTimeInterface::RFC3339_EXTENDED</code></strong></dt>
<dt>
<strong><code>DATE_RFC3339_EXTENDED</code></strong></dt>
<dd>
<span class="simpara">
RFC 3339 EXTENDED format (since PHP 7.0.0) (example: 2005-08-15T15:52:01.000+00:00)
</span>
</dd>
<dt id="datetime.constants.rss"><strong><code>DateTimeInterface::RSS</code></strong></dt>
<dt>
<strong><code>DATE_RSS</code></strong></dt>
<dd>
<span class="simpara">
RSS (example: Mon, 15 Aug 2005 15:52:01 +0000)
</span>
</dd>
<dt id="datetime.constants.w3c"><strong><code>DateTimeInterface::W3C</code></strong></dt>
<dt>
<strong><code>DATE_W3C</code></strong></dt>
<dd>
<span class="simpara">
World Wide Web Consortium (example: 2005-08-15T15:52:01+00:00)
</span>
</dd>
</dl>
</div>
<div class="section" id="datetimeinterface.changelog">
<h2 class="title">Changelog</h2>
<p class="para">
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Description</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>7.2.0</td>
<td>
The class constants of <a href="class.datetime.html" class="classname">DateTime</a> are now defined
on <strong class="classname">DateTimeInterface</strong>.
</td>
</tr>
<tr>
<td>5.5.8</td>
<td>
Trying to implement <strong class="classname">DateTimeInterface</strong> raises a
fatal error now. Formerly implementing the interface didn't raise an
error, but the behavior was erroneous.
</td>
</tr>
</tbody>
</table>
</p>
</div>
</div>
<h2>Table of Contents</h2><ul class="chunklist chunklist_reference"><li><a href="datetime.diff.html">DateTime::diff</a> — Returns the difference between two DateTime objects</li><li><a href="datetime.format.html">DateTime::format</a> — Returns date formatted according to given format</li><li><a href="datetime.getoffset.html">DateTime::getOffset</a> — Returns the timezone offset</li><li><a href="datetime.gettimestamp.html">DateTime::getTimestamp</a> — Gets the Unix timestamp</li><li><a href="datetime.gettimezone.html">DateTime::getTimezone</a> — Return time zone relative to given DateTime</li><li><a href="datetime.wakeup.html">DateTime::__wakeup</a> — The __wakeup handler</li></ul>
</div>
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