HTML: POST array not showing unchecked checkbox

<td>
  <input type="checkbox" name="cb[]"/>
  <input type="checkbox" name="cb[]"/>
</td>

• Solution 1) Explicit index + hidden trick

<td>
  <input type="hidden" name="cb[0]" value=""/>
  <input type="checkbox" name="cb[0]"/>
  <input type="hidden" name="cb[1]" value=""/>
  <input type="checkbox" name="cb[1]"/>
</td>

• Solution 2) Explicit index + fill in the blanks (e.g. with PHP)

<td>
  <input type="checkbox" name="cb[0]"/>
  <input type="checkbox" name="cb[1]"/>
</td>

$post_array = $_POST['cb'];
$defaults = array_fill(0, 2, '0');
$post_array = $post_array + $defaults;