Source of: /manual/en/language.operators.array.php
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<div id="language.operators.array" class="sect1">
<h2 class="title">Array Operators</h2>
<table class="doctable table">
<caption><b>Array Operators</b></caption>
<thead valign="middle">
<tr valign="middle">
<th>Example</th>
<th>Name</th>
<th>Result</th>
</tr>
</thead>
<tbody valign="middle" class="tbody">
<tr valign="middle">
<td align="left">$a + $b</td>
<td align="left">Union</td>
<td align="left">Union of <var class="varname">$a</var> and <var class="varname">$b</var>.</td>
</tr>
<tr valign="middle">
<td align="left">$a == $b</td>
<td align="left">Equality</td>
<td align="left"><b><tt class="constant">TRUE</tt></b> if <var class="varname">$a</var> and <var class="varname">$b</var> have the same key/value pairs.</td>
</tr>
<tr valign="middle">
<td align="left">$a === $b</td>
<td align="left">Identity</td>
<td align="left"><b><tt class="constant">TRUE</tt></b> if <var class="varname">$a</var> and <var class="varname">$b</var> have the same key/value pairs in the same
order and of the same types.</td>
</tr>
<tr valign="middle">
<td align="left">$a != $b</td>
<td align="left">Inequality</td>
<td align="left"><b><tt class="constant">TRUE</tt></b> if <var class="varname">$a</var> is not equal to <var class="varname">$b</var>.</td>
</tr>
<tr valign="middle">
<td align="left">$a <> $b</td>
<td align="left">Inequality</td>
<td align="left"><b><tt class="constant">TRUE</tt></b> if <var class="varname">$a</var> is not equal to <var class="varname">$b</var>.</td>
</tr>
<tr valign="middle">
<td align="left">$a !== $b</td>
<td align="left">Non-identity</td>
<td align="left"><b><tt class="constant">TRUE</tt></b> if <var class="varname">$a</var> is not identical to <var class="varname">$b</var>.</td>
</tr>
</tbody>
</table>
<p class="para">
The <i>+</i> operator
appends elements of remaining keys from the right handed array to the
left handed, whereas duplicated keys are NOT overwritten.
</p>
<p class="para">
</p><div class="informalexample">
<div class="example-contents programlisting">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$a </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"a" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"apple"</span><span style="color: #007700">, </span><span style="color: #DD0000">"b" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"banana"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"a" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"pear"</span><span style="color: #007700">, </span><span style="color: #DD0000">"b" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"strawberry"</span><span style="color: #007700">, </span><span style="color: #DD0000">"c" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"cherry"</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$c </span><span style="color: #007700">= </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: #FF8000">// Union of $a and $b<br /></span><span style="color: #007700">echo </span><span style="color: #DD0000">"Union of \$a and \$b: \n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$c </span><span style="color: #007700">= </span><span style="color: #0000BB">$b </span><span style="color: #007700">+ </span><span style="color: #0000BB">$a</span><span style="color: #007700">; </span><span style="color: #FF8000">// Union of $b and $a<br /></span><span style="color: #007700">echo </span><span style="color: #DD0000">"Union of \$b and \$a: \n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$c</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div><p>
When executed, this script will print the following:
<div class="example-contents screen">
<div class="cdata"><pre>
Union of $a and $b:
array(3) {
["a"]=>
string(5) "apple"
["b"]=>
string(6) "banana"
["c"]=>
string(6) "cherry"
}
Union of $b and $a:
array(3) {
["a"]=>
string(4) "pear"
["b"]=>
string(10) "strawberry"
["c"]=>
string(6) "cherry"
}
</pre></div>
</div>
</p>
<p class="para">
Elements of arrays are equal for the comparison if they have the
same key and value.
</p>
<p class="para">
</p><div class="example">
<p><b>Example #1 Comparing arrays</b></p>
<div class="example-contents programlisting">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$a </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"apple"</span><span style="color: #007700">, </span><span style="color: #DD0000">"banana"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= array(</span><span style="color: #0000BB">1 </span><span style="color: #007700">=> </span><span style="color: #DD0000">"banana"</span><span style="color: #007700">, </span><span style="color: #DD0000">"0" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"apple"</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$a </span><span style="color: #007700">== </span><span style="color: #0000BB">$b</span><span style="color: #007700">); </span><span style="color: #FF8000">// bool(true)<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$a </span><span style="color: #007700">=== </span><span style="color: #0000BB">$b</span><span style="color: #007700">); </span><span style="color: #FF8000">// bool(false)<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div><p>
</p>
<p class="para">
See also the manual sections on the
<a href="language.types.array.php" class="link">Array type</a> and
<a href="ref.array.php" class="link">Array functions</a>.
</p>
</div><?php manual_footer(); ?>
