title: Php, in_array, 0 value
body: <p>I was trying to understand the <code>in_array</code> behavior at the next scenario:</p>
  
  <pre><code>$arr = array(2 =&gt; 'Bye', 52, 77, 3 =&gt; 'Hey');
  var_dump(in_array(0, $arr));
  </code></pre>
  
  <p>The returned value of the <code>in_array()</code> is boolean <code>true</code>. As you can see there is <strong>no</strong> value equal to <code>0</code>, so if can some one please help me understand why does the function return true?</p>