ence
          of integer, float, and multiple string keys using string_sort:
        </p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">DATA_TYPE</span> <span class="special">{</span>
  <span class="identifier">time_t</span> <span class="identifier">birth</span><span class="special">;</span>
  <span class="keyword">float</span> <span class="identifier">net_worth</span><span class="special">;</span>
  <span class="identifier">string</span> <span class="identifier">