an class="keyword">int</span> <span class="special">&gt;</span> <a name="idp43960304-bb"></a><span class="identifier">host_rank</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
<p>Retrieves the rank of the host process, if one exists.</p>
<p>If there is a host process, this routine returns the rank of that process. Otherwise, it returns an empty <code class="computeroutput">optional&lt;int&gt;</code>. MPI does not define the meaning of a "host" process: 