     Determine whether the socket is at the out-of-band data mark.
          </p>
<pre class="programlisting">bool at_mark(
    boost::system::error_code &amp; ec) const;
</pre>
<p>
            This function is used to check whether the socket input is currently
            positioned at the out-of-band data mark.
          </p>
<h6>
<a name="boost_asio.reference.basic_socket.at_mark.overload2.h0"></a>
            <span class="phrase"><a name="boost_asio.reference.basic_socket.at_mark.overload2.parameters">