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<title>NULL</title>
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</div><hr /><div id="language.types.null" class="sect1">
<h2 class="title">NULL</h2>
<p class="para">
The special <strong><code>NULL</code></strong> value represents a variable with no value. <strong><code>NULL</code></strong> is the
only possible value of type <span class="type"><a href="language.types.null.html" class="type null">null</a></span>.
</p>
<p class="para">
A variable is considered to be <span class="type"><a href="language.types.null.html" class="type null">null</a></span> if:
</p>
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
it has been assigned the constant <strong><code>NULL</code></strong>.
</p>
</li>
<li class="listitem">
<p class="para">
it has not been set to any value yet.
</p>
</li>
<li class="listitem">
<p class="para">
it has been <span class="function"><a href="function.unset.html" class="function">unset()</a></span>.
</p>
</li>
</ul>
<div class="sect2" id="language.types.null.syntax">
<h3 class="title">Syntax</h3>
<p class="para">
There is only one value of type <span class="type"><a href="language.types.null.html" class="type null">null</a></span>, and that is the
case-insensitive constant <strong><code>NULL</code></strong>.
</p>
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$var </span><span style="color: #007700">= </span><span style="color: #0000BB">NULL</span><span style="color: #007700">; <br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
<p class="para">
See also the functions <span class="function"><a href="function.is-null.html" class="function">is_null()</a></span> and
<span class="function"><a href="function.unset.html" class="function">unset()</a></span>.
</p>
</div>
<div class="sect2" id="language.types.null.casting">
<h3 class="title">Casting to <strong><code>NULL</code></strong></h3>
<p class="para">
Casting a variable to <span class="type"><a href="language.types.null.html" class="type null">null</a></span> using <em>(unset) $var</em>
will <em class="emphasis">not</em> remove the variable or unset its value.
It will only return a <strong><code>NULL</code></strong> value.
</p>
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