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<title>Determine whether a variable is empty</title>
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</div><hr /><div id="function.empty" class="refentry">
<div class="refnamediv">
<h1 class="refname">empty</h1>
<p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">empty</span> — <span class="dc-title">Determine whether a variable is empty</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.empty-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>empty</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">$var</code></span>
)</div>
<p class="para rdfs-comment">
Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals <strong><code>FALSE</code></strong>. <span class="function"><strong>empty()</strong></span> does not generate a warning if the variable does not exist.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.empty-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">var</code></em></span>
<dd>
<p class="para">
Variable to be checked
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Prior to PHP 5.5, <span class="function"><strong>empty()</strong></span> only supports variables;
anything else will result in a parse error. In other words, the
following will not work: <strong class="command">empty(trim($name))</strong>.
Instead, use <strong class="command">trim($name) == false</strong>.
</p>
</p></blockquote>
<p class="para">
No warning is generated if the variable does not exist.
That means <span class="function"><strong>empty()</strong></span> is essentially the
concise equivalent to <strong class="command">!isset($var) || $var == false</strong>.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.empty-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>FALSE</code></strong> if <em><code class="parameter">var</code></em> exists and has a non-empty, non-zero value.
Otherwise returns <strong><code>TRUE</code></strong>.
</p>
<p class="para">
The following things are considered to be empty:
<ul class="simplelist">
<li class="member"><em>""</em> (an empty string)</li>
<li class="member"><em>0</em> (0 as an integer)</li>
<li class="member"><em>0.0</em> (0 as a float)</li>
<li class="member"><em>"0"</em> (0 as a string)</li>
<li class="member"><strong><code>NULL</code></strong></li>
<li class="member"><strong><code>FALSE</code></strong></li>
<li class="member"><em>array()</em> (an empty array)</li>
<li class="member"><em>$var;</em> (a variable declared, but without a value)</li>
</ul>
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.empty-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>5.5.0</td>
<td>
<p class="para">
<span class="function"><strong>empty()</strong></span> now supports expressions, rather than only
variables.
</p>
</td>
</tr>
<tr>
<td>5.4.0</td>
<td>
<p class="para">
Checking non-numeric offsets of strings returns <strong><code>TRUE</code></strong>.
</p>
</td>
</tr>
<tr>
<td>5.0.0</td>
<td>
<p class="para">
Objects with no properties are no longer considered empty.
</p>
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.empty-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-5247">
<p><strong>Example #1
A simple <span class="function"><strong>empty()</strong></span> / <span class="function"><a href="function.isset.html" class="function">isset()</a></span>
comparison.
</strong></p>
<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">0</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// Evaluates to true because $var is empty<br /></span><span style="color: #007700">if (empty(</span><span style="color: #0000BB">$var</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">'$var is either 0, empty, or not set at all'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// Evaluates as true because $var is set<br /></span><span style="color: #007700">if (isset(</span><span style="color: #0000BB">$var</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">'$var is set even though it is empty'</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<div class="example" id="example-5248">
<p><strong>Example #2 <span class="function"><strong>empty()</strong></span> on String Offsets</strong></p>
<div class="example-contents"><p>
PHP 5.4 changes how <span class="function"><strong>empty()</strong></span> behaves
when passed string offsets.
</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$expected_array_got_string </span><span style="color: #007700">= </span><span style="color: #DD0000">'somestring'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(empty(</span><span style="color: #0000BB">$expected_array_got_string</span><span style="color: #007700">[</span><span style="color: #DD0000">'some_key'</span><span style="color: #007700">]));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(empty(</span><span style="color: #0000BB">$expected_array_got_string</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(empty(</span><span style="color: #0000BB">$expected_array_got_string</span><span style="color: #007700">[</span><span style="color: #DD0000">'0'</span><span style="color: #007700">]));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(empty(</span><span style="color: #0000BB">$expected_array_got_string</span><span style="color: #007700">[</span><span style="color: #0000BB">0.5</span><span style="color: #007700">]));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(empty(</span><span style="color: #0000BB">$expected_array_got_string</span><span style="color: #007700">[</span><span style="color: #DD0000">'0.5'</span><span style="color: #007700">]));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(empty(</span><span style="color: #0000BB">$expected_array_got_string</span><span style="color: #007700">[</span><span style="color: #DD0000">'0 Mostel'</span><span style="color: #007700">]));<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>Output of the above example in PHP 5.3:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
</pre></div>
</div>
<div class="example-contents"><p>Output of the above example in PHP 5.4:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
bool(true)
bool(false)
bool(false)
bool(false)
bool(true)
bool(true)
</pre></div>
</div>
</div>
</div>
<div class="refsect1 notes" id="refsect1-function.empty-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">Because this is a
language construct and not a function, it cannot be called using
<a href="functions.variable-functions.html" class="link">variable functions</a>.</span>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
When using <span class="function"><strong>empty()</strong></span> on inaccessible object properties,
the <a href="language.oop5.overloading.html#object.isset" class="link">__isset()</a>
overloading method will be called, if declared.
</p>
</p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-function.empty-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.isset.html" class="function" rel="rdfs-seeAlso">isset()</a> - Determine if a variable is set and is not NULL</span></li>
<li class="member"><a href="language.oop5.overloading.html#object.isset" class="link">__isset()</a></li>
<li class="member"> <span class="function"><a href="function.unset.html" class="function" rel="rdfs-seeAlso">unset()</a> - Unset a given variable</span></li>
<li class="member"> <span class="function"><a href="function.array-key-exists.html" class="function" rel="rdfs-seeAlso">array_key_exists()</a> - Checks if the given key or index exists in the array</span></li>
<li class="member"> <span class="function"><a href="function.count.html" class="function" rel="rdfs-seeAlso">count()</a> - Count all elements in an array, or something in an object</span></li>
<li class="member"> <span class="function"><a href="function.strlen.html" class="function" rel="rdfs-seeAlso">strlen()</a> - Get string length</span></li>
<li class="member"><a href="types.comparisons.html" class="link">The type comparison tables</a></li>
</ul>
</p>
</div>
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