_MAG</a></li>
		</ul>
	<h4>Requirements</h4>
		<div>
			<b>Header:</b> &nbsp;<a href="../headers/control/expr_if.hpp.html">&lt;boost/preprocessor/control/expr_if.hpp&gt;</a>
		</div>
	<h4>Sample Code</h4>
<div><pre>
#include &lt;<a href="../headers/control/expr_if.hpp.html">boost/preprocessor/control/expr_if.hpp</a>&gt;
#include &lt;<a href="../headers/tuple/elem.hpp.html">boost/preprocessor/tuple/elem.hpp</a>&gt;

#define CV(n) \
   <a href="expr_if.html">BOOST_PP_EXPR_IF</a>( \
      n, \
      <a href="t