PHP. What does "return($var & 1);" mean?
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/6201134/callback-function-return-returnvar-1">callback function return return($var &amp; 1)?</a>  </p>
</blockquote>



<p>Example code:</p>

<pre><code>&lt;?php
function odd($var)
{
    // returns whether the input integer is odd
    return($var &amp; 1);
}

function even($var)
{
    // returns whether the input integer is even
    return(!($var &amp; 1));
}

$array1 = array("a"=&gt;1, "b"=&gt;2, "c"=&gt;3, "d"=&gt;4, "e"=&gt;5);
$array2 = array(6, 7, 8, 9, 10, 11, 12);

echo "Odd :\n";
print_r(array_filter($array1, "odd"));
echo "Even:\n";
print_r(array_filter($array2, "even"));
?&gt;
</code></pre>

<p>what does this kind of code mean:</p>

<pre><code> return  (x &amp; y) 
</code></pre>

<p>?</p>
