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<title>Boost.Preprocessor - Reference</title>
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<h3><a href="../../../../index.htm"><img height="86" width="277" alt="C++ Boost" src="../../../../c++boost.gif" border="0"></a></h3>
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<h1 align="center">Boost.Preprocessor</h1>
<h2 align="center">Reference</h2>
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<a href="for.htm">Prev</a> <a href="if.htm">Next</a> <a href="index.htm#Macros">Macros</a> <a href="index.htm#Headers">Headers</a>
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<h1>#include <<a href="../../../../boost/preprocessor/identity.hpp">boost/preprocessor/identity.hpp</a>></h1>
<hr>
<h2><a name="BOOST_PP_IDENTITY">#define BOOST_PP_IDENTITY</a>(X)</h2>
<p>Expands to <code>X</code> once invoked.</p>
<p>Designed to be used with <a href="if.htm#BOOST_PP_IF">BOOST_PP_IF</a>(), when one of the clauses need to be
invoked.</p>
<p>For example,</p>
<pre>
<a href="if.htm#BOOST_PP_IF">BOOST_PP_IF</a>(1,<a href="identity.htm#BOOST_PP_IDENTITY">BOOST_PP_IDENTITY</a>(X),<a href="empty.htm#BOOST_PP_EMPTY">BOOST_PP_EMPTY</a>)<b>()</b>
</pre>
<p>expands to:</p>
<pre>
X
</pre>
<h3>Test</h3>
<ul>
<li><a href="../../test/preprocessor_test.cpp">preprocessor_test.cpp</a></li>
</ul>
<hr>
<h2><a name="BOOST_PREPROCESSOR_IDENTITY">#define BOOST_PREPROCESSOR_IDENTITY</a>(X)</h2>
<p>Obsolete. Use <a href="identity.htm#BOOST_PP_IDENTITY">BOOST_PP_IDENTITY</a>().</p>
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