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<title>Caching by last modification</title>
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<div class="refnamediv">
<h1 class="refname">http_cache_last_modified</h1>
<p class="verinfo">(PECL pecl_http >= 0.1.0)</p><p class="refpurpose"><span class="refname">http_cache_last_modified</span> — <span class="dc-title">Caching by last modification</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.http-cache-last-modified-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>http_cache_last_modified</strong></span>
([ <span class="methodparam"><span class="type">int</span> <code class="parameter">$timestamp_or_expires</code></span>
] )</div>
<p class="para rdfs-comment">
Attempts to cache the sent entity by its last modification date.
</p>
<p class="para">
If the supplied argument is greater than 0, it is handled as timestamp
and will be sent as date of last modification. If it is 0 or omitted,
the current time will be sent as <em>Last-Modified</em> date.
If it's negative, it is handled as expiration time in seconds, which means
that if the requested last modification date is not between the calculated timespan,
the <em>Last-Modified</em> header is updated and the actual body will be sent.
</p>
<p class="para">
A log entry will be written to the cache log if the <a href="http.configuration.html" class="link">INI setting</a>
<a href="" class="link">http.log.cache</a> is set
and the cache attempt was successful.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">This function may be used in conjunction with
<span class="function"><a href="function.http-send-data.html" class="function">http_send_data()</a></span>, <span class="function"><a href="function.http-send-file.html" class="function">http_send_file()</a></span> and <span class="function"><a href="function.http-send-stream.html" class="function">http_send_stream()</a></span>.</span></p></blockquote>
</div>
<div class="refsect1 parameters" id="refsect1-function.http-cache-last-modified-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">timestamp_or_expires</code></em></span>
<dd>
<p class="para">
Unix timestamp
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.http-cache-last-modified-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>FALSE</code></strong> or <em class="emphasis">exits</em> on success with <em>304 Not Modified</em> if the entity is cached.
See the <a href="http.configuration.html" class="link">INI setting</a>
<a href="" class="link">http.force_exit</a> for what "exits" means.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.http-cache-last-modified-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-4359">
<p><strong>Example #1 A <span class="function"><strong>http_cache_last_modified()</strong></span> example</strong></p>
<div class="example-contents"><p>
Caching for 5 seconds.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />http_cache_last_modified</span><span style="color: #007700">(-</span><span style="color: #0000BB">5</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"%s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">http_date</span><span style="color: #007700">());<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.http-cache-last-modified-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.http-cache-etag.html" class="function" rel="rdfs-seeAlso">http_cache_etag()</a> - Caching by ETag</span></li>
<li class="member">the <a href="class.httpresponse.html" class="link">
<a href="class.httpresponse.html" class="classname">HttpResponse</a></a> class if you are using PHP 5.1.0
and above</li>
</ul>
</p>
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