scasting means casting across an
      inheritance hierarchy diagram, such as from one base to the other in a <code class="literal">Y</code>
      diagram hierarchy.
    </p>
<p>
      Such casts can be done with old-style casts, but this approach is never to
      be recommended. Old-style casts are sorely lacking in type safety, suffer poor
      readability, and are difficult to locate with search tools.
    </p>
<p>
      <a name="polymorphic_downcast"></a>The C++ built-in <code class="computeroutput">s