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<title>Alters the timestamp</title>
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<h1 class="refname">DateTime::modify</h1>
<h1 class="refname">date_modify</h1>
<p class="verinfo">(PHP 5 >= 5.2.0)</p><p class="refpurpose"><span class="refname">DateTime::modify</span> -- <span class="refname">date_modify</span> — <span class="dc-title">Alters the timestamp</span></p>
</div>
<div class="refsect1 description" id="refsect1-datetime.modify-description">
<h3 class="title">Description</h3>
<p class="para">Object oriented style</p>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type"><a href="class.datetime.html" class="type DateTime">DateTime</a></span> <span class="methodname"><strong>DateTime::modify</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$modify</code></span>
)</div>
<p class="para rdfs-comment">Procedural style</p>
<div class="methodsynopsis dc-description">
<span class="type"><a href="class.datetime.html" class="type DateTime">DateTime</a></span> <span class="methodname"><a href="function.date-modify.html" class="methodname">date_modify</a></span>
( <span class="methodparam"><span class="type"><a href="class.datetime.html" class="type DateTime">DateTime</a></span> <code class="parameter">$object</code></span>
, <span class="methodparam"><span class="type">string</span> <code class="parameter">$modify</code></span>
)</div>
<p class="para rdfs-comment">
Alter the timestamp of a DateTime object by incrementing or decrementing in a
format accepted by <span class="function"><a href="function.strtotime.html" class="function">strtotime()</a></span>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-datetime.modify-parameters">
<h3 class="title">Parameters</h3>
<dl>
<dt>
<span class="term"><em><code class="parameter">object</code></em></span>
<dd>
<p class="para">Procedural style only: A <a href="class.datetime.html" class="classname">DateTime</a> object
returned by <span class="function"><a href="function.date-create.html" class="function">date_create()</a></span>.
The function modifies this object.</p></dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">modify</code></em></span>
<dd>
<p class="para">A date/time string. Valid formats are explained in <a href="datetime.formats.html" class="link">Date and Time Formats</a>.</p>
</dd>
</dt>
</dl>
</div>
<div class="refsect1 returnvalues" id="refsect1-datetime.modify-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns the <a href="class.datetime.html" class="classname">DateTime</a> object for method chaining or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 changelog" id="refsect1-datetime.modify-changelog">
<h3 class="title">Changelog</h3>
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Description</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>5.3.6</td>
<td>
Absolute date/time statements now take effect.
Previously, only relative parts were used.
</td>
</tr>
<tr><td>5.3.0</td><td>Changed the
return value on success from <strong><code>NULL</code></strong> to <a href="class.datetime.html" class="classname">DateTime</a>.</td></tr>
</tbody>
</table>
</div>
<div class="refsect1 examples" id="refsect1-datetime.modify-examples">
<h3 class="title">Examples</h3>
<div class="example" id="example-2258">
<p><strong>Example #1 <span class="function"><strong>DateTime::modify()</strong></span> example</strong></p>
<div class="example-contents"><p>Object oriented style</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$date </span><span style="color: #007700">= new </span><span style="color: #0000BB">DateTime</span><span style="color: #007700">(</span><span style="color: #DD0000">'2006-12-12'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$date</span><span style="color: #007700">-></span><span style="color: #0000BB">modify</span><span style="color: #007700">(</span><span style="color: #DD0000">'+1 day'</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$date</span><span style="color: #007700">-></span><span style="color: #0000BB">format</span><span style="color: #007700">(</span><span style="color: #DD0000">'Y-m-d'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>Procedural style</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$date </span><span style="color: #007700">= </span><span style="color: #0000BB">date_create</span><span style="color: #007700">(</span><span style="color: #DD0000">'2006-12-12'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">date_modify</span><span style="color: #007700">(</span><span style="color: #0000BB">$date</span><span style="color: #007700">, </span><span style="color: #DD0000">'+1 day'</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">date_format</span><span style="color: #007700">(</span><span style="color: #0000BB">$date</span><span style="color: #007700">, </span><span style="color: #DD0000">'Y-m-d'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above examples will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
2006-12-13
</pre></div>
</div>
</div>
<div class="example" id="example-2259">
<p><strong>Example #2 Beware when adding or subtracting months</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$date </span><span style="color: #007700">= new </span><span style="color: #0000BB">DateTime</span><span style="color: #007700">(</span><span style="color: #DD0000">'2000-12-31'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$date</span><span style="color: #007700">-></span><span style="color: #0000BB">modify</span><span style="color: #007700">(</span><span style="color: #DD0000">'+1 month'</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$date</span><span style="color: #007700">-></span><span style="color: #0000BB">format</span><span style="color: #007700">(</span><span style="color: #DD0000">'Y-m-d'</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$date</span><span style="color: #007700">-></span><span style="color: #0000BB">modify</span><span style="color: #007700">(</span><span style="color: #DD0000">'+1 month'</span><span style="color: #007700">);<br />echo </span><span style="color: #0000BB">$date</span><span style="color: #007700">-></span><span style="color: #0000BB">format</span><span style="color: #007700">(</span><span style="color: #DD0000">'Y-m-d'</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
2001-01-31
2001-03-03
</pre></div>
</div>
</div>
</div>
<div class="refsect1 seealso" id="refsect1-datetime.modify-seealso">
<h3 class="title">See Also</h3>
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.strtotime.html" class="function" rel="rdfs-seeAlso">strtotime()</a> - Parse about any English textual datetime description into a Unix timestamp</span></li>
<li class="member"> <span class="function"><a href="datetime.add.html" class="function" rel="rdfs-seeAlso">DateTime::add()</a> - Adds an amount of days, months, years, hours, minutes and seconds to a
DateTime object</span></li>
<li class="member"> <span class="function"><a href="datetime.sub.html" class="function" rel="rdfs-seeAlso">DateTime::sub()</a> - Subtracts an amount of days, months, years, hours, minutes and seconds from
a DateTime object</span></li>
<li class="member"> <span class="function"><a href="datetime.setdate.html" class="function" rel="rdfs-seeAlso">DateTime::setDate()</a> - Sets the date</span></li>
<li class="member"> <span class="function"><a href="datetime.setisodate.html" class="function" rel="rdfs-seeAlso">DateTime::setISODate()</a> - Sets the ISO date</span></li>
<li class="member"> <span class="function"><a href="datetime.settime.html" class="function" rel="rdfs-seeAlso">DateTime::setTime()</a> - Sets the time</span></li>
<li class="member"> <span class="function"><a href="datetime.settimestamp.html" class="function" rel="rdfs-seeAlso">DateTime::setTimestamp()</a> - Sets the date and time based on an Unix timestamp</span></li>
</ul>
</div>
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