<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Pairs</title> <link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../../index.html" title="Chapter 1. Fusion 2.0"> <link rel="up" href="../tuple.html" title="Tuple"> <link rel="prev" href="class_template_tuple/relational_operators.html" title="Relational operators"> <link rel="next" href="../extension.html" title="Extension"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td> <td align="center"><a href="../../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a 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class="link" href="pairs.html#fusion.tuple.pairs.description">Description</a> </h5> <p> The <a href="http://std.dkuug.dk/jtc1/sc22/wg21/docs/papers/2002/n1403.pdf" target="_top">TR1 Tuple</a> interface is specified to provide uniform access to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code> as if it were a 2 element tuple. </p> <a name="fusion.tuple.pairs.specification"></a><h5> <a name="id1093342"></a> <a class="link" href="pairs.html#fusion.tuple.pairs.specification">Specification</a> </h5> <pre class="programlisting"><span class="identifier">tuple_size</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">></span> <span class="special">>::</span><span class="identifier">value</span> </pre> <p> <span class="bold"><strong>Type</strong></span>: An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL Integral Constant</a> </p> <p> <span class="bold"><strong>Value</strong></span>: Returns 2, the number of elements in a pair. </p> <pre class="programlisting"><span class="identifier">tuple_element</span><span class="special"><</span><span class="number">0</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">></span> <span class="special">>::</span><span class="identifier">type</span> </pre> <p> <span class="bold"><strong>Type</strong></span>: <code class="computeroutput"><span class="identifier">T1</span></code> </p> <p> <span class="bold"><strong>Value</strong></span>: Returns the type of the first element of the pair </p> <pre class="programlisting"><span class="identifier">tuple_element</span><span class="special"><</span><span class="number">1</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">></span> <span class="special">>::</span><span class="identifier">type</span> </pre> <p> <span class="bold"><strong>Type</strong></span>: <code class="computeroutput"><span class="identifier">T2</span></code> </p> <p> <span class="bold"><strong>Value</strong></span>: Returns thetype of the second element of the pair </p> <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">int</span> <span class="identifier">I</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T2</span><span class="special">></span> <span class="identifier">P</span><span class="special">&</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">>&</span> <span class="identifier">pr</span><span class="special">);</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">int</span> <span class="identifier">I</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T1</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T2</span><span class="special">></span> <span class="keyword">const</span> <span class="identifier">P</span><span class="special">&</span> <span class="identifier">get</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">>&</span> <span class="identifier">pr</span><span class="special">);</span> </pre> <p> <span class="bold"><strong>Type</strong></span>: If <code class="computeroutput"><span class="identifier">I</span> <span class="special">==</span> <span class="number">0</span></code> <code class="computeroutput"><span class="identifier">P</span></code> is <code class="computeroutput"><span class="identifier">T1</span></code>, else if <code class="computeroutput"><span class="identifier">I</span> <span class="special">==</span> <span class="number">1</span></code> <code class="computeroutput"><span class="identifier">P</span></code> is <code class="computeroutput"><span class="identifier">T2</span></code> else the program is ill-formed. </p> <p> <span class="bold"><strong>Returns: <code class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">first</span></code> if <code class="computeroutput"><span class="identifier">I</span> <span class="special">==</span> <span class="number">0</span></code> else <code class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">second</span></code>.</strong></span>[*Returns: <code class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">first</span></code> if <code class="computeroutput"><span class="identifier">I</span> <span class="special">==</span> <span class="number">0</span></code> else <code class="computeroutput"><span class="identifier">pr</span><span class="special">.</span><span class="identifier">second</span></code>. </p> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias Schwinger<p> Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="class_template_tuple/relational_operators.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../tuple.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../extension.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>