| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <head> |
| <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> |
| <title>Arguments</title> |
| <link rel="stylesheet" href="../../../boostbook.css" type="text/css"> |
| <meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> |
| <link rel="home" href="../../../index.html" title="Chapter 1. Phoenix 3.0"> |
| <link rel="up" href="../primitives.html" title="Primitives"> |
| <link rel="prev" href="references.html" title="References"> |
| <link rel="next" href="../composites.html" title="Composites"> |
| </head> |
| <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> |
| <table cellpadding="2" width="100%"><tr><td valign="top"></td></tr></table> |
| <hr> |
| <div class="spirit-nav"> |
| <a accesskey="p" href="references.html"><img src="../../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../primitives.html"><img src="../../../images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../images/home.png" alt="Home"></a><a accesskey="n" href="../composites.html"><img src="../../../images/next.png" alt="Next"></a> |
| </div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="phoenix.starter_kit.primitives.arguments"></a><a class="link" href="arguments.html" title="Arguments">Arguments</a> |
| </h4></div></div></div> |
| <p> |
| Arguments are also functions? You bet! |
| </p> |
| <p> |
| Until now, we have been dealing with expressions returning a nullary function. |
| Arguments, on the other hand, evaluate to an N-ary function. An argument |
| represents the Nth argument. There are a few predefined arguments arg1, |
| arg2, arg3, arg4 and so on (and it's <a href="http://www.boost.org/libs/lambda/doc/index.html" target="_top">BLL</a> |
| counterparts: _1, _2, _3, _4 and so on). Examples: |
| </p> |
| <pre class="programlisting"><span class="identifier">arg1</span> <span class="comment">// one-or-more argument function that returns its first argument |
| </span><span class="identifier">arg2</span> <span class="comment">// two-or-more argument function that returns its second argument |
| </span><span class="identifier">arg3</span> <span class="comment">// three-or-more argument function that returns its third argument |
| </span></pre> |
| <p> |
| <code class="computeroutput"><span class="identifier">argN</span></code> returns the Nth argument. |
| Examples: |
| </p> |
| <pre class="programlisting"><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">3</span><span class="special">;</span> |
| <span class="keyword">char</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">s</span> <span class="special">=</span> <span class="string">"Hello World"</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">arg1</span><span class="special">(</span><span class="identifier">i</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints 3 |
| </span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">arg2</span><span class="special">(</span><span class="identifier">i</span><span class="special">,</span> <span class="identifier">s</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints "Hello World" |
| </span></pre> |
| <p> |
| (See <a href="../../../../../example/arguments.cpp" target="_top">arguments.cpp</a>) |
| </p> |
| <div class="sidebar"> |
| <div class="titlepage"></div> |
| <p> |
| <span class="inlinemediaobject"><img src="../../../images/tip.png" alt="tip"></span> Learn more about arguments <a class="link" href="../../modules/core/arguments.html" title="Arguments">here.</a> |
| </p> |
| </div> |
| </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 © 2002-2005, 2010 Joel de Guzman, Dan Marsden, Thomas Heller<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="references.html"><img src="../../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../primitives.html"><img src="../../../images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../images/home.png" alt="Home"></a><a accesskey="n" href="../composites.html"><img src="../../../images/next.png" alt="Next"></a> |
| </div> |
| </body> |
| </html> |
