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<html>
<head>
<title>BOOST_PP_LPAREN_IF</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<div style="margin-left: 0px;">
The <b>BOOST_PP_LPAREN_IF</b> macro conditionally expands to a left parenthesis.
</div>
<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_LPAREN_IF</b>(<i>cond</i>)
</div>
<h4>Arguments</h4>
<dl>
<dt>cond</dt>
<dd>
The condition that determines if a the macro expands to a left parenthesis or nothing.
Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.
</dd>
</dl>
<h4>Remarks</h4>
<div>
If <i>cond</i> expands to <i>0</i>, this macro expands to nothing.
Otherwise, it expands to a left parenthesis.
</div>
<div>
The preprocessor interprets parentheses as delimiters in macro invocations.
Because of this, parentheses require special handling.
</div>
<h4>See Also</h4>
<ul>
<li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
<li><a href="rparen_if.html">BOOST_PP_RPAREN_IF</a></li>
</ul>
<h4>Requirements</h4>
<div>
<b>Header:</b> <a href="../headers/punctuation/paren_if.html"><boost/preprocessor/punctuation/paren_if.hpp></a>
</div>
<h4>Sample Code</h4>
<div><pre>
#include <<a href="../headers/punctuation/paren_if.html">boost/preprocessor/punctuation/paren_if.hpp</a>>
#define MACRO(c, x) <a href="lparen_if.html">BOOST_PP_LPAREN_IF</a>(c) x <a href="rparen_if.html">BOOST_PP_RPAREN_IF</a>(c)
MACRO(0, text) // expands to text
MACRO(1, text) // expands to (text)
</pre></div>
<hr size="1">
<div style="margin-left: 0px;">
<i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
</br><i>© Copyright Paul Mensonides 2002</i>
</div>
<div style="margin-left: 0px;">
<p><small>Distributed under the Boost Software License, Version 1.0. (See
accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
copy at <a href=
"http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
</div>
</body>
</html>
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