.match_results.empty"></a><pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">empty</span><span class="special">()</span><span class="keyword">const</span><span class="special">;</span>
</pre>
<p>
        <span class="bold"><strong>Effects</strong></span>: Returns size() == 0.
      </p>
<a name="boost_regex.match_results.length"></a><pre class="programlisting"><span class="identifier">difference_type</span> <span class="identifier">length</span><span class="special">(</sp