<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Array Operators</title> </head> <body><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.operators.string.html">String Operators</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.operators.type.html">Type Operators</a></div> <div class="up"><a href="language.operators.html">Operators</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div><hr /><div id="language.operators.array" class="sect1"> <h2 class="title">Array Operators</h2> <table class="doctable table"> <caption><strong>Array Operators</strong></caption> <thead> <tr> <th>Example</th> <th>Name</th> <th>Result</th> </tr> </thead> <tbody class="tbody"> <tr> <td>$a + $b</td> <td>Union</td> <td>Union of <var class="varname"><var class="varname">$a</var></var> and <var class="varname"><var class="varname">$b</var></var>.</td> </tr> <tr> <td>$a == $b</td> <td>Equality</td> <td><strong><code>TRUE</code></strong> if <var class="varname"><var class="varname">$a</var></var> and <var class="varname"><var class="varname">$b</var></var> have the same key/value pairs.</td> </tr> <tr> <td>$a === $b</td> <td>Identity</td> <td><strong><code>TRUE</code></strong> if <var class="varname"><var class="varname">$a</var></var> and <var class="varname"><var class="varname">$b</var></var> have the same key/value pairs in the same order and of the same types.</td> </tr> <tr> <td>$a != $b</td> <td>Inequality</td> <td><strong><code>TRUE</code></strong> if <var class="varname"><var class="varname">$a</var></var> is not equal to <var class="varname"><var class="varname">$b</var></var>.</td> </tr> <tr> <td>$a <> $b</td> <td>Inequality</td> <td><strong><code>TRUE</code></strong> if <var class="varname"><var class="varname">$a</var></var> is not equal to <var class="varname"><var class="varname">$b</var></var>.</td> </tr> <tr> <td>$a !== $b</td> <td>Non-identity</td> <td><strong><code>TRUE</code></strong> if <var class="varname"><var class="varname">$a</var></var> is not identical to <var class="varname"><var class="varname">$b</var></var>.</td> </tr> </tbody> </table> <p class="para"> The <em>+</em> operator returns the right-hand array appended to the left-hand array; for keys that exist in both arrays, the elements from the left-hand array will be used, and the matching elements from the right-hand array will be ignored. </p> <p class="para"> <div class="informalexample"> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />$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> 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 $a: array(3) { ["a"]=> string(4) "pear" ["b"]=> string(10) "strawberry" ["c"]=> string(6) "cherry" } </pre></div> </div> </p> <p class="para"> Elements of arrays are equal for the comparison if they have the same key and value. </p> <p class="para"> <div class="example" id="example-127"> <p><strong>Example #1 Comparing arrays</strong></p> <div class="example-contents"> <div class="phpcode"><code><span style="color: #000000"> <span style="color: #0000BB"><?php<br />$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 class="para"> See also the manual sections on the <a href="language.types.array.html" class="link">Array type</a> and <a href="ref.array.html" class="link">Array functions</a>. </p> </div><hr /><div class="manualnavbar" style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="language.operators.string.html">String Operators</a></div> <div class="next" style="text-align: right; float: right;"><a href="language.operators.type.html">Type Operators</a></div> <div class="up"><a href="language.operators.html">Operators</a></div> <div class="home"><a href="index.html">PHP Manual</a></div> </div></body></html>