     <span class="keyword">public</span><span class="special">:</span>
        <span class="keyword">virtual</span> <span class="keyword">const</span> <span class="keyword">char</span> <span class="special">*</span><span class="identifier">what</span><span class="special">()</span> <span class="keyword">const</span> <span class="comment">// throw()</span>
        <span class="special">{</span>
            <span class="keyword">return</span> <span class="string">"bad numeric conversion: positive overflow"</s