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<title>BOOST_PP_IDENTITY</title>
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The <b>BOOST_PP_IDENTITY</b> macro expands to its argument when invoked.
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<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_IDENTITY</b>(<i>item</i>)()
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<h4>Arguments</h4>
<dl>
<dt>item</dt>
<dd>
The result of the expansion.
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<h4>Remarks</h4>
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This macro is designed to be used with <b>BOOST_PP_IF</b> and <b>BOOST_PP_IIF</b> when only one of the clauses needs to be invoked.
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<h4>See Also</h4>
<ul>
<li><a href="if.html">BOOST_PP_IF</a></li>
<li><a href="iif.html">BOOST_PP_IIF</a></li>
</ul>
<h4>Requirements</h4>
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<b>Header:</b> <a href="../headers/facilities/identity.html"><boost/preprocessor/facilities/identity.hpp></a>
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<h4>Sample Code</h4>
<div><pre>
#include <<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>>
#include <<a href="../headers/facilities/empty.html">boost/preprocessor/facilities/empty.hpp</a>>
#include <<a href="../headers/facilities/identity.html">boost/preprocessor/facilities/identity.hpp</a>>
#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, <a href="identity.html">BOOST_PP_IDENTITY</a>(x), <a href="empty.html">BOOST_PP_EMPTY</a>)()
MACRO(0) // expands to nothing
MACRO(1) // expands to x
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