mirror of
https://github.com/boostorg/preprocessor.git
synced 2025-07-15 13:36:33 +02:00
51 lines
1.6 KiB
HTML
51 lines
1.6 KiB
HTML
<html>
|
|
<head>
|
|
<title>BOOST_PP_COMMA_IF</title>
|
|
<link rel="stylesheet" type="text/css" href="../styles.css">
|
|
<script language="javascript" type="text/javascript" src="../scripts.js"></script>
|
|
</head>
|
|
<body onload="init('sample');">
|
|
<div style="margin-left: 0px;">
|
|
The <b>BOOST_PP_COMMA_IF</b> macro conditionally expands to a comma.
|
|
</div>
|
|
<h4>Usage</h4>
|
|
<div class="code">
|
|
<b>BOOST_PP_COMMA_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 comma 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 comma.
|
|
</div>
|
|
<div>
|
|
The preprocessor interprets commas as argument separators in macro invocations.
|
|
Because of this, commas require special handling.
|
|
</div>
|
|
<h4>See Also</h4>
|
|
<ul>
|
|
<li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
|
|
</ul>
|
|
<h4>Requirements</h4>
|
|
<div>
|
|
<b>Header:</b> <a href="../headers/punctuation/comma_if.hpp.html"><boost/preprocessor/punctuation/comma_if.hpp></a>
|
|
</div>
|
|
<h4><a class="local" onclick="toggle('sample');" onmouseover="change(this);" onmouseout="revert(this);">Sample Code</a></h4>
|
|
<div id="sample"><pre>
|
|
#include <boost/preprocessor/punctuation/comma_if.hpp>
|
|
#include <boost/preprocessor/repetition/repeat.hpp>
|
|
|
|
#define MACRO(z, n, text) BOOST_PP_COMMA_IF(n) text
|
|
|
|
BOOST_PP_REPEAT(3, MACRO, class) // expands to class, class, class
|
|
<pre></div>
|
|
</body>
|
|
</html>
|