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<title>Generates a storable representation of a value</title>
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</div><hr /><div id="function.serialize" class="refentry">
<div class="refnamediv">
<h1 class="refname">serialize</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">serialize</span> — <span class="dc-title">Generates a storable representation of a value</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.serialize-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">string</span> <span class="methodname"><strong>serialize</strong></span>
( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$value</code></span>
)</div>
<p class="para rdfs-comment">
Generates a storable representation of a value.
</p>
<p class="para">
This is useful for storing or passing PHP values around without
losing their type and structure.
</p>
<p class="para">
To make the serialized string into a PHP value again, use
<span class="function"><a href="function.unserialize.html" class="function">unserialize()</a></span>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.serialize-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">value</code></em></span>
<dd>
<p class="para">
The value to be serialized. <span class="function"><strong>serialize()</strong></span>
handles all types, except the <span class="type"><a href="language.types.resource.html" class="type resource">resource</a></span>-type.
You can even <span class="function"><strong>serialize()</strong></span> arrays that contain
references to itself. Circular references inside the array/object you
are serializing will also be stored. Any other
reference will be lost.
</p>
<p class="para">
When serializing objects, PHP will attempt to call the member function
<a href="language.oop5.magic.html#object.sleep" class="link">__sleep()</a> prior to serialization.
This is to allow the object to do any last minute clean-up, etc. prior
to being serialized. Likewise, when the object is restored using
<span class="function"><a href="function.unserialize.html" class="function">unserialize()</a></span> the <a href="language.oop5.magic.html#object.wakeup" class="link">__wakeup()</a> member function is called.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Object's private members have the class name prepended to the member
name; protected members have a '*' prepended to the member name.
These prepended values have null bytes on either side.
</p>
</p></blockquote>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.serialize-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns a string containing a byte-stream representation of
<em><code class="parameter">value</code></em> that can be stored anywhere.
</p>
<p class="para">
Note that this is a binary string which may include null bytes, and needs
to be stored and handled as such. For example,
<span class="function"><strong>serialize()</strong></span> output should generally be stored in a BLOB
field in a database, rather than a CHAR or TEXT field.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.serialize-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-5271">
<p><strong>Example #1 <span class="function"><strong>serialize()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// $session_data contains a multi-dimensional array with session<br />// information for the current user. We use serialize() to store<br />// it in a database at the end of the request.<br /><br /></span><span style="color: #0000BB">$conn </span><span style="color: #007700">= </span><span style="color: #0000BB">odbc_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"webdb"</span><span style="color: #007700">, </span><span style="color: #DD0000">"php"</span><span style="color: #007700">, </span><span style="color: #DD0000">"chicken"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$stmt </span><span style="color: #007700">= </span><span style="color: #0000BB">odbc_prepare</span><span style="color: #007700">(</span><span style="color: #0000BB">$conn</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"UPDATE sessions SET data = ? WHERE id = ?"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$sqldata </span><span style="color: #007700">= array (</span><span style="color: #0000BB">serialize</span><span style="color: #007700">(</span><span style="color: #0000BB">$session_data</span><span style="color: #007700">), </span><span style="color: #0000BB">$_SERVER</span><span style="color: #007700">[</span><span style="color: #DD0000">'PHP_AUTH_USER'</span><span style="color: #007700">]);<br />if (!</span><span style="color: #0000BB">odbc_execute</span><span style="color: #007700">(</span><span style="color: #0000BB">$stmt</span><span style="color: #007700">, </span><span style="color: #0000BB">$sqldata</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$stmt </span><span style="color: #007700">= </span><span style="color: #0000BB">odbc_prepare</span><span style="color: #007700">(</span><span style="color: #0000BB">$conn</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"INSERT INTO sessions (id, data) VALUES(?, ?)"</span><span style="color: #007700">);<br /> if (!</span><span style="color: #0000BB">odbc_execute</span><span style="color: #007700">(</span><span style="color: #0000BB">$stmt</span><span style="color: #007700">, </span><span style="color: #0000BB">$sqldata</span><span style="color: #007700">)) {<br /> </span><span style="color: #FF8000">/* Something went wrong.. */<br /> </span><span style="color: #007700">}<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.serialize-changelog">
<h3 class="title">Changelog</h3>
<p class="para">
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Description</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>4.0.7</td>
<td>
The object serialization process was fixed.
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 notes" id="refsect1-function.serialize-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Note that many built-in PHP objects cannot be serialized. However, those with
this ability either implement the <span class="interfacename"><a href="class.serializable.html" class="interfacename">Serializable</a></span> interface or the
magic <a href="language.oop5.magic.html#object.sleep" class="link">__sleep()</a> and
<a href="language.oop5.magic.html#object.wakeup" class="link">__wakeup()</a> methods. If an
internal class does not fulfill any of those requirements, it cannot reliably be
serialized.
</p>
<p class="para">
There are some historical exceptions to the above rule, where some internal objects
could be serialized without implementing the interface or exposing the methods. Notably,
the <a href="class.arrayobject.html" class="classname">ArrayObject</a> prior to PHP 5.2.0.
</p>
</p></blockquote>
<div class="warning"><strong class="warning">Warning</strong>
<p class="para">
When <span class="function"><strong>serialize()</strong></span> serializes objects, the leading slash is not included in the class name of namespaced classes for maximum compatibility.
</p>
</div>
</div>
<div class="refsect1 seealso" id="refsect1-function.serialize-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.unserialize.html" class="function" rel="rdfs-seeAlso">unserialize()</a> - Creates a PHP value from a stored representation</span></li>
<li class="member"> <span class="function"><a href="function.var-export.html" class="function" rel="rdfs-seeAlso">var_export()</a> - Outputs or returns a parsable string representation of a variable</span></li>
<li class="member"> <span class="function"><a href="function.json-encode.html" class="function" rel="rdfs-seeAlso">json_encode()</a> - Returns the JSON representation of a value</span></li>
<li class="member"><a href="language.oop5.serialization.html" class="link">Serializing Objects</a></li>
<li class="member"><a href="language.oop5.magic.html#object.sleep" class="link">__sleep()</a></li>
<li class="member"><a href="language.oop5.magic.html#object.wakeup" class="link">__wakeup()</a></li>
</ul>
</p>
</div>
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