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</div><hr /><div id="control-structures.foreach" class="sect1">
<h2 class="title"><em>foreach</em></h2>
<p class="verinfo">(PHP 4, PHP 5)</p>
<p class="para">
The <em>foreach</em> construct provides an easy way to
iterate over arrays. <em>foreach</em> works only on arrays
and objects, and will issue an error when you try to use it on a variable
with a different data type or an uninitialized variable. There are two
syntaxes:
<div class="informalexample">
<div class="example-contents">
<div class="cdata"><pre>
foreach (array_expression as $value)
statement
foreach (array_expression as $key => $value)
statement
</pre></div>
</div>
</div>
</p>
<p class="simpara">
The first form loops over the array given by
<em>array_expression</em>. On each iteration, the value of
the current element is assigned to <em>$value</em> and
the internal array pointer is advanced by one (so on the next
iteration, you'll be looking at the next element).
</p>
<p class="simpara">
The second form will additionally assign the current element's key to
the <em>$key</em> variable on each iteration.
</p>
<p class="simpara">
It is possible to
<a href="language.oop5.iterations.html" class="link">customize object iteration</a>.
</p>
<p class="para">
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
When <em>foreach</em> first starts executing, the
internal array pointer is automatically reset to the first element
of the array. This means that you do not need to call
<span class="function"><a href="function.reset.html" class="function">reset()</a></span> before a <em>foreach</em>
loop.
</p>
<p class="para">
As <em>foreach</em> relies on the internal array pointer, changing it
within the loop may lead to unexpected behavior.
</p>
</p></blockquote>
</p>
<p class="para">
In order to be able to directly modify array elements within the loop precede
<em>$value</em> with &. In that case the value will be assigned by
<a href="language.references.html" class="link">reference</a>.
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$arr </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">);<br />foreach (</span><span style="color: #0000BB">$arr </span><span style="color: #007700">as &</span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$value </span><span style="color: #007700">= </span><span style="color: #0000BB">$value </span><span style="color: #007700">* </span><span style="color: #0000BB">2</span><span style="color: #007700">;<br />}<br /></span><span style="color: #FF8000">// $arr is now array(2, 4, 6, 8)<br /></span><span style="color: #007700">unset(</span><span style="color: #0000BB">$value</span><span style="color: #007700">); </span><span style="color: #FF8000">// break the reference with the last element<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
Referencing <em>$value</em> is only possible if the iterated array can be
referenced (i.e. if it is a variable). The following code won't work:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">foreach (array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">) as &</span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$value </span><span style="color: #007700">= </span><span style="color: #0000BB">$value </span><span style="color: #007700">* </span><span style="color: #0000BB">2</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<div class="warning"><strong class="warning">Warning</strong>
<p class="para">
Reference of a <em>$value</em> and the last array element
remain even after the <em>foreach</em> loop. It is recommended
to destroy it by <span class="function"><a href="function.unset.html" class="function">unset()</a></span>.
</p>
</div>
<p class="para">
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
<em>foreach</em> does not support the ability to
suppress error messages using '@'.
</p>
</p></blockquote>
</p>
<p class="para">
You may have noticed that the following are functionally
identical:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$arr </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"one"</span><span style="color: #007700">, </span><span style="color: #DD0000">"two"</span><span style="color: #007700">, </span><span style="color: #DD0000">"three"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">reset</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr</span><span style="color: #007700">);<br />while (list(, </span><span style="color: #0000BB">$value</span><span style="color: #007700">) = </span><span style="color: #0000BB">each</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"Value: </span><span style="color: #0000BB">$value</span><span style="color: #DD0000"><br />\n"</span><span style="color: #007700">;<br />}<br /><br />foreach (</span><span style="color: #0000BB">$arr </span><span style="color: #007700">as </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Value: </span><span style="color: #0000BB">$value</span><span style="color: #DD0000"><br />\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
The following are also functionally identical:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$arr </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"one"</span><span style="color: #007700">, </span><span style="color: #DD0000">"two"</span><span style="color: #007700">, </span><span style="color: #DD0000">"three"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">reset</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr</span><span style="color: #007700">);<br />while (list(</span><span style="color: #0000BB">$key</span><span style="color: #007700">, </span><span style="color: #0000BB">$value</span><span style="color: #007700">) = </span><span style="color: #0000BB">each</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"Key: </span><span style="color: #0000BB">$key</span><span style="color: #DD0000">; Value: </span><span style="color: #0000BB">$value</span><span style="color: #DD0000"><br />\n"</span><span style="color: #007700">;<br />}<br /><br />foreach (</span><span style="color: #0000BB">$arr </span><span style="color: #007700">as </span><span style="color: #0000BB">$key </span><span style="color: #007700">=> </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Key: </span><span style="color: #0000BB">$key</span><span style="color: #DD0000">; Value: </span><span style="color: #0000BB">$value</span><span style="color: #DD0000"><br />\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
Some more examples to demonstrate usage:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">/* foreach example 1: value only */<br /><br /></span><span style="color: #0000BB">$a </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">17</span><span style="color: #007700">);<br /><br />foreach (</span><span style="color: #0000BB">$a </span><span style="color: #007700">as </span><span style="color: #0000BB">$v</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Current value of \$a: </span><span style="color: #0000BB">$v</span><span style="color: #DD0000">.\n"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">/* foreach example 2: value (with its manual access notation printed for illustration) */<br /><br /></span><span style="color: #0000BB">$a </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">17</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$i </span><span style="color: #007700">= </span><span style="color: #0000BB">0</span><span style="color: #007700">; </span><span style="color: #FF8000">/* for illustrative purposes only */<br /><br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">$a </span><span style="color: #007700">as </span><span style="color: #0000BB">$v</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"\$a[</span><span style="color: #0000BB">$i</span><span style="color: #DD0000">] => </span><span style="color: #0000BB">$v</span><span style="color: #DD0000">.\n"</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$i</span><span style="color: #007700">++;<br />}<br /><br /></span><span style="color: #FF8000">/* foreach example 3: key and value */<br /><br /></span><span style="color: #0000BB">$a </span><span style="color: #007700">= array(<br /> </span><span style="color: #DD0000">"one" </span><span style="color: #007700">=> </span><span style="color: #0000BB">1</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"two" </span><span style="color: #007700">=> </span><span style="color: #0000BB">2</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"three" </span><span style="color: #007700">=> </span><span style="color: #0000BB">3</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"seventeen" </span><span style="color: #007700">=> </span><span style="color: #0000BB">17<br /></span><span style="color: #007700">);<br /><br />foreach (</span><span style="color: #0000BB">$a </span><span style="color: #007700">as </span><span style="color: #0000BB">$k </span><span style="color: #007700">=> </span><span style="color: #0000BB">$v</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"\$a[</span><span style="color: #0000BB">$k</span><span style="color: #DD0000">] => </span><span style="color: #0000BB">$v</span><span style="color: #DD0000">.\n"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">/* foreach example 4: multi-dimensional arrays */<br /></span><span style="color: #0000BB">$a </span><span style="color: #007700">= array();<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">][</span><span style="color: #0000BB">0</span><span style="color: #007700">] = </span><span style="color: #DD0000">"a"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">][</span><span style="color: #0000BB">1</span><span style="color: #007700">] = </span><span style="color: #DD0000">"b"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">][</span><span style="color: #0000BB">0</span><span style="color: #007700">] = </span><span style="color: #DD0000">"y"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">][</span><span style="color: #0000BB">1</span><span style="color: #007700">] = </span><span style="color: #DD0000">"z"</span><span style="color: #007700">;<br /><br />foreach (</span><span style="color: #0000BB">$a </span><span style="color: #007700">as </span><span style="color: #0000BB">$v1</span><span style="color: #007700">) {<br /> foreach (</span><span style="color: #0000BB">$v1 </span><span style="color: #007700">as </span><span style="color: #0000BB">$v2</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$v2</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br /> }<br />}<br /><br /></span><span style="color: #FF8000">/* foreach example 5: dynamic arrays */<br /><br /></span><span style="color: #007700">foreach (array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #0000BB">5</span><span style="color: #007700">) as </span><span style="color: #0000BB">$v</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$v</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<div class="sect2" id="control-structures.foreach.list">
<h3 class="title">Unpacking nested arrays with list()</h3>
<p class="verinfo">(PHP 5 >= 5.5.0)</p>
<p class="para">
PHP 5.5 added the ability to iterate over an array of arrays and unpack the
nested array into loop variables by providing a <span class="function"><a href="function.list.html" class="function">list()</a></span>
as the value.
</p>
<p class="para">
For example:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$array </span><span style="color: #007700">= [<br /> [</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">],<br /> [</span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">],<br />];<br /><br />foreach (</span><span style="color: #0000BB">$array </span><span style="color: #007700">as list(</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">)) {<br /> </span><span style="color: #FF8000">// $a contains the first element of the nested array,<br /> // and $b contains the second element.<br /> </span><span style="color: #007700">echo </span><span style="color: #DD0000">"A: </span><span style="color: #0000BB">$a</span><span style="color: #DD0000">; B: </span><span style="color: #0000BB">$b</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
A: 1; B: 2
A: 3; B: 4
</pre></div>
</div>
</div>
</p>
<p class="para">
You can provide fewer elements in the <span class="function"><a href="function.list.html" class="function">list()</a></span> than there
are in the nested array, in which case the leftover array values will be
ignored:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$array </span><span style="color: #007700">= [<br /> [</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">],<br /> [</span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">],<br />];<br /><br />foreach (</span><span style="color: #0000BB">$array </span><span style="color: #007700">as list(</span><span style="color: #0000BB">$a</span><span style="color: #007700">)) {<br /> </span><span style="color: #FF8000">// Note that there is no $b here.<br /> </span><span style="color: #007700">echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$a</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
1
3
</pre></div>
</div>
</div>
</p>
<p class="para">
A notice will be generated if there aren't enough array elements to fill
the <span class="function"><a href="function.list.html" class="function">list()</a></span>:
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$array </span><span style="color: #007700">= [<br /> [</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">],<br /> [</span><span style="color: #0000BB">3</span><span style="color: #007700">, </span><span style="color: #0000BB">4</span><span style="color: #007700">],<br />];<br /><br />foreach (</span><span style="color: #0000BB">$array </span><span style="color: #007700">as list(</span><span style="color: #0000BB">$a</span><span style="color: #007700">, </span><span style="color: #0000BB">$b</span><span style="color: #007700">, </span><span style="color: #0000BB">$c</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"A: </span><span style="color: #0000BB">$a</span><span style="color: #DD0000">; B: </span><span style="color: #0000BB">$b</span><span style="color: #DD0000">; C: </span><span style="color: #0000BB">$c</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<p class="para">The above example will output:</p>
<div class="example-contents screen">
<div class="cdata"><pre>
Notice: Undefined offset: 2 in example.php on line 7
A: 1; B: 2; C:
Notice: Undefined offset: 2 in example.php on line 7
A: 3; B: 4; C:
</pre></div>
</div>
</div>
</p>
</div>
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