| Brian Silverman | f27e085 | 2018-08-04 23:56:45 -0700 | [diff] [blame^] | 1 | <html> |
| 2 | <head> |
| 3 | <title>BOOST_PP_LIST_FIRST</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_FIRST</b> macro expands to the head of a <i>list</i>. |
| 9 | </div> |
| 10 | <h4>Usage</h4> |
| 11 | <div class="code"> |
| 12 | <b>BOOST_PP_LIST_FIRST</b>(<i>list</i>) |
| 13 | </div> |
| 14 | <h4>Arguments</h4> |
| 15 | <dl> |
| 16 | <dt>list</dt> |
| 17 | <dd> |
| 18 | A non-nil <i>list</i>. |
| 19 | </dd> |
| 20 | </dl> |
| 21 | <h4>Requirements</h4> |
| 22 | <div> |
| 23 | <b>Header:</b> <a href="../headers/list/adt.html"><boost/preprocessor/list/adt.hpp></a> |
| 24 | </div> |
| 25 | <h4>Sample Code</h4> |
| 26 | <div><pre> |
| 27 | #include <<a href="../headers/list/adt.html">boost/preprocessor/list/adt.hpp</a>> |
| 28 | |
| 29 | #define OLD \ |
| 30 | <a href="list_cons.html">BOOST_PP_LIST_CONS</a>( \ |
| 31 | a, \ |
| 32 | <a href="list_cons.html">BOOST_PP_LIST_CONS</a>( \ |
| 33 | b, \ |
| 34 | <a href="list_cons.html">BOOST_PP_LIST_CONS</a>( \ |
| 35 | c, \ |
| 36 | <a href="list_nil.html">BOOST_PP_LIST_NIL</a> \ |
| 37 | ) \ |
| 38 | ) \ |
| 39 | ) \ |
| 40 | /**/ |
| 41 | |
| 42 | #define NEW (a, (b, (c, <a href="nil.html">BOOST_PP_NIL</a>))) |
| 43 | |
| 44 | <a href="list_first.html">BOOST_PP_LIST_FIRST</a>(OLD) == <a href="list_first.html">BOOST_PP_LIST_FIRST</a>(NEW) |
| 45 | // expands to a == a |
| 46 | |
| 47 | <a href="list_rest.html">BOOST_PP_LIST_REST</a>(OLD) == <a href="list_rest.html">BOOST_PP_LIST_REST</a>(NEW) |
| 48 | // expands to (b, (c, <a href="nil.html">BOOST_PP_NIL</a>)) == (b, (c, <a href="nil.html">BOOST_PP_NIL</a>)) |
| 49 | </pre></div> |
| 50 | <hr size="1"> |
| 51 | <div style="margin-left: 0px;"> |
| 52 | <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i> |
| 53 | </br><i>© Copyright Paul Mensonides 2002</i> |
| 54 | </div> |
| 55 | <div style="margin-left: 0px;"> |
| 56 | <p><small>Distributed under the Boost Software License, Version 1.0. (See |
| 57 | accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or |
| 58 | copy at <a href= |
| 59 | "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p> |
| 60 | </div> |
| 61 | </body> |
| 62 | </html> |