How does this php code return odd numbers?
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/600202/understanding-phps-operator">Understanding PHP&#39;s &amp; operator</a>  </p>
</blockquote>



<p>I was just looking at array_filter() function doc and they had the following code to return odd numbers...</p>

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

<p>Why does $var &amp; 1 return odd number? how does that work?</p>
