e selected promotion policy. These "checked" cast operations return
        values of type <a class="link" href="checked_result.html" title="checked_result&lt;R&gt;"><code class="computeroutput">checked_result&lt;R&gt;</code></a>.</p></li>
<li class="listitem"><p>If either of the casting operations fails, an exception is
        handled in accordance with the exception policy.</p></li>
<li class="listitem"><p>Otherwise, the operation is performed using "<a class="link" href="checked_arithmetic.html" title="