preprocessor/doc/ref/tuple_elem.html

65 lines
2.8 KiB
HTML
Raw Permalink Blame History

<html>
<head>
<title>BOOST_PP_TUPLE_ELEM</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<div style="margin-left: 0px;">
The <b>BOOST_PP_TUPLE_ELEM</b> macro extracts an element from a <i>tuple</i>.
</div>
<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_TUPLE_ELEM</b>(<i>size</i>, <i>i</i>, <i>tuple</i>)<sup></sup><br>
<br>
or<br>
<br>
<b>BOOST_PP_TUPLE_ELEM</b>(<i>...</i>) <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><b></b><br>
</div>
<h4>Arguments</h4>
<dl>
<dt>size</dt>
<dd>
The size of the <i>tuple</i>.&nbsp;
Valid <i>tuple</i> sizes range from <i>1</i> to <b>BOOST_PP_LIMIT_TUPLE</b>.&nbsp;
</dd>
<dt>i</dt>
<dd>
The zero-based index into the <i>tuple</i> of the element to be extracted.&nbsp;
Valid values range from <i>0</i> to <i>size</i> - <i>1</i>.
</dd>
<dt>tuple</dt>
<dd>
The <i>tuple</i> from which an element is to be extracted.
</dd>
</dl>
<h4>Remarks</h4>
<div>
The <i>size</i> argument must be the actual size of the <i>tuple</i>,
and <i>i</i> must be less than the size of the <i>tuple</i>. <br>
<br>You can
invoke the variadic version as BOOST_PP_TUPLE_ELEM(<i>i</i>,<i>tuple</i>) or
BOOST_PP_TUPLE_ELEM(<i>size</i>,<i>i</i>,<i>tuple</i>).
</div>
<h4>See Also</h4>
<ul>
<li><a href="limit_tuple.html">BOOST_PP_LIMIT_TUPLE</a></li>
</ul>
<h4>Requirements</h4>
<div>
<b>Header:</b> &nbsp;<a href="../headers/tuple/elem.html">&lt;boost/preprocessor/tuple/elem.hpp&gt;</a>
</div>
<h4>Sample Code</h4>
<div><pre>#include &lt;<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>&gt;<br><br>#define TUPLE (a, b, c, d)<br><br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, TUPLE) // expands to a<br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 3, TUPLE) // expands to d<br><br>// or for the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br><br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(0, TUPLE) // expands to a in the variadic version<br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(3, TUPLE) // expands to d in the variadic version<br></pre></div>
<hr size="1">
<div style="margin-left: 0px;">
<i><EFBFBD> Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
<br><i><EFBFBD> Copyright Paul Mensonides 2002<br>
</i><i><EFBFBD> Copyright Edward Diener 2011,2013</i><br>
</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>