1<html> 2<head> 3 <title>BOOST_PP_LIST_AT</title> 4 <link rel="stylesheet" type="text/css" href="../styles.css"> 5</head> 6<body> 7 <div style="margin-left: 0px;"> 8 The <b>BOOST_PP_LIST_AT</b> macro extracts an element in a <i>list</i>. 9 </div> 10 <h4>Usage</h4> 11 <div class="code"> 12 <b>BOOST_PP_LIST_AT</b>(<i>list</i>, <i>index</i>) 13 </div> 14 <h4>Arguments</h4> 15 <dl> 16 <dt>list</dt> 17 <dd> 18 The <i>list</i> from which a element is to be extracted. 19 This <i>list</i> must have at least <i>index</i> + <i>1</i> elements. 20 </dd> 21 <dt>index</dt> 22 <dd> 23 The zero-based position in the <i>list</i> of the element to be extracted. 24 </dd> 25 </dl> 26 <h4>Remarks</h4> 27 <div> 28 Previously, this macro could not be used inside <b>BOOST_PP_WHILE</b>. 29 There is no longer any such restriction. 30 It is more efficient, however, to use <b>BOOST_PP_LIST_AT_D</b> in such a situation. 31 </div> 32 <h4>See Also</h4> 33 <ul> 34 <li><a href="list_at_d.html">BOOST_PP_LIST_AT_D</a></li> 35 </ul> 36 <h4>Requirements</h4> 37 <div> 38 <b>Header:</b> <a href="../headers/list/at.html"><boost/preprocessor/list/at.hpp></a> 39 </div> 40 <h4>Sample Code</h4> 41<div><pre> 42#include <<a href="../headers/list/at.html">boost/preprocessor/list/at.hpp</a>> 43 44#define LIST (a, (b, (c, <a href="nil.html">BOOST_PP_NIL</a>))) 45 46<a href="list_at.html">BOOST_PP_LIST_AT</a>(LIST, 0) // expands to a 47<a href="list_at.html">BOOST_PP_LIST_AT</a>(LIST, 2) // expands to c 48</pre></div> 49 <hr size="1"> 50 <div style="margin-left: 0px;"> 51 <i>� Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i> 52 </br><i>� Copyright Paul Mensonides 2002</i> 53 </div> 54 <div style="margin-left: 0px;"> 55 <p><small>Distributed under the Boost Software License, Version 1.0. (See 56 accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or 57 copy at <a href= 58 "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p> 59 </div> 60</body> 61</html> 62