</em></span> to streambuf and not just a streambuf?  Well,
      the [io]streams hold pointers (or references, depending on the
      implementation) to their buffers, not the actual
      buffers.  This allows polymorphic behavior on the chapter of the buffers
      as well as the streams themselves.  The pointer is easily retrieved
      using the <code class="code">rdbuf()</code> member function.  Therefore, the easiest
      way to copy the file is:
   </p><pre class="programlisting">
   OUT &lt;&lt; IN