<html> <head> <title>BOOST_PP_LIST_AT_D</title> <link rel="stylesheet" type="text/css" href="../styles.css"> </head> <body> <div style="margin-left: 0px;"> The <b>BOOST_PP_LIST_AT_D</b> macro extracts an element in a <i>list</i>. It reenters <b>BOOST_PP_WHILE</b> with maximum efficiency. </div> <h4>Usage</h4> <div class="code"> <b>BOOST_PP_LIST_AT_D</b>(<i>d</i>, <i>list</i>, <i>index</i>) </div> <h4>Arguments</h4> <dl> <dt>d</dt> <dd> The next available <b>BOOST_PP_WHILE</b> iteration. </dd> <dt>list</dt> <dd> The <i>list</i> from which a element is to be extracted. This <i>list</i> must have at least <i>index</i> + <i>1</i> elements. </dd> <dt>index</dt> <dd> The zero-based position in the <i>list</i> of the element to be extracted. </dd> </dl> <h4>See Also</h4> <ul> <li><a href="list_at.html">BOOST_PP_LIST_AT</a></li> </ul> <h4>Requirements</h4> <div> <b>Header:</b> <a href="../headers/list/at.hpp.html"><boost/preprocessor/list/at.hpp></a> </div> <h4>Sample Code</h4> <div><pre> #include <<a href="../headers/control/while.hpp.html">boost/preprocessor/control/while.hpp</a>> #include <<a href="../headers/list/at.hpp.html">boost/preprocessor/list/at.hpp</a>> #define LIST (7, (2, (0, (1, <a href="nil.html">BOOST_PP_NIL</a>)))) #define PRED(d, state) <a href="list_at_d.html">BOOST_PP_LIST_AT_D</a>(d, state, 0) #define OP(d, state) <a href="list_rest.html">BOOST_PP_LIST_REST</a>(state) <a href="while.html">BOOST_PP_WHILE</a>(PRED, OP, LIST) // expands to (0, (1, <a href="nil.html">BOOST_PP_NIL</a>)) </pre></div> </body> </html>
