1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> 7<title>The MPL Reference Manual: pair</title> 8<link rel="stylesheet" href="../style.css" type="text/css" /> 9</head> 10<body class="docframe refmanual"> 11<table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./data-types-miscellaneous.html" class="navigation-link">Prev</a> <a href="./empty-base.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group">Back <a href="./empty-base.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./data-types-miscellaneous.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 12<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./data-types.html" class="navigation-link">Data Types</a> / <a href="./data-types-miscellaneous.html" class="navigation-link">Miscellaneous</a> / <a href="./pair.html" class="navigation-link">pair</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="pair"> 15<h1><a class="toc-backref" href="./data-types-miscellaneous.html#id1583">pair</a></h1> 16<div class="section" id="id1271"> 17<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> 18<pre class="literal-block"> 19template< 20 typename T1 21 , typename T2 22 > 23struct <a href="./pair.html" class="identifier">pair</a> 24{ 25 typedef <a href="./pair.html" class="identifier">pair</a> type; 26 typedef T1 first; 27 typedef T2 second; 28}; 29</pre> 30</div> 31<div class="section" id="id1272"> 32<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 33<p>A transparent holder for two arbitrary types.</p> 34</div> 35<div class="section" id="id1273"> 36<h3><a class="subsection-title" href="#header" name="header">Header</a></h3> 37<pre class="literal-block"> 38#include <<a href="../../../../boost/mpl/pair.hpp" class="header">boost/mpl/pair.hpp</a>> 39</pre> 40</div> 41<div class="section" id="id1274"> 42<h3><a class="subsection-title" href="#example" name="example">Example</a></h3> 43<p>Count a number of elements in the sequence together with a number of negative 44elements among these.</p> 45<pre class="literal-block"> 46typedef <a href="./fold.html" class="identifier">fold</a>< 47 <a href="./vector-c.html" class="identifier">vector_c</a><int,-1,0,5,-7,-2,4,5,7> 48 , <a href="./pair.html" class="identifier">pair</a>< <a href="./int.html" class="identifier">int_</a><0>, <a href="./int.html" class="identifier">int_</a><0> > 49 , <a href="./pair.html" class="identifier">pair</a>< 50 <a href="./next.html" class="identifier">next</a>< first<<a href="./placeholders.html" class="identifier">_1</a>> > 51 , <a href="./if.html" class="identifier">if_</a>< 52 <a href="./less.html" class="identifier">less</a>< <a href="./placeholders.html" class="identifier">_2</a>, <a href="./int.html" class="identifier">int_</a><0> > 53 , <a href="./next.html" class="identifier">next</a>< second<<a href="./placeholders.html" class="identifier">_1</a>> > 54 , second<<a href="./placeholders.html" class="identifier">_1</a>> 55 > 56 > 57 >::type p; 58 59<a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( p::first::value, ==, 8 ); 60<a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( p::second::value, ==, 3 ); 61</pre> 62</div> 63<div class="section" id="id1275"> 64<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 65<p><a class="reference internal" href="./data-types.html">Data Types</a>, <a class="reference internal" href="./sequences.html">Sequences</a>, <a class="reference internal" href="./trivial-metafunctions-summary.html#first">first</a>, <a class="reference internal" href="./trivial-metafunctions-summary.html#second">second</a></p> 66<!-- Data Types/Miscellaneous//empty_base |20 --> 67</div> 68</div> 69 70<div class="footer-separator"></div> 71<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./data-types-miscellaneous.html" class="navigation-link">Prev</a> <a href="./empty-base.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group">Back <a href="./empty-base.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./data-types-miscellaneous.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 72<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 73Distributed under the Boost Software License, Version 1.0. (See accompanying 74file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body> 75</html> 76