forked from boostorg/optional
55 lines
3.7 KiB
HTML
55 lines
3.7 KiB
HTML
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
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<title>Problem</title>
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<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css">
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<meta name="generator" content="DocBook XSL Stylesheets V1.78.1">
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<link rel="home" href="../../index.html" title="Chapter 1. Boost.Optional">
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<link rel="up" href="../introduction.html" title="Introduction">
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<link rel="prev" href="../introduction.html" title="Introduction">
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<link rel="next" href="solution.html" title="Solution">
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</head>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
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<table cellpadding="2" width="100%"><tr>
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<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td>
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<td align="center"><a href="../../../../../../index.html">Home</a></td>
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<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td>
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<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
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<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
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<td align="center"><a href="../../../../../../more/index.htm">More</a></td>
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<a accesskey="p" href="../introduction.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../introduction.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="solution.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="optional.introduction.problem"></a><a class="link" href="problem.html" title="Problem">Problem</a>
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</h3></div></div></div>
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<p>
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Suppose we want to read a parameter form a config file which represents some
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integral value, let's call it <code class="computeroutput"><span class="string">"MaxValue"</span></code>.
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It is possible that this parameter is not specified; such situation is no
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error. It is valid to not specify the parameter and in that case the program
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is supposed to behave slightly different. Also suppose that any possible
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value of type <code class="computeroutput"><span class="keyword">int</span></code> is a valid
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value for <code class="computeroutput"><span class="string">"MaxValue"</span></code>,
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so we cannot jut use <code class="computeroutput"><span class="special">-</span><span class="number">1</span></code>
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to represent the absence of the parameter in the config file.
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</p>
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</div>
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<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<br>Copyright © 2014 Andrzej Krzemieński<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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>)
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</p>
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</div></td>
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</tr></table>
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<hr>
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<div class="spirit-nav">
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<a accesskey="p" href="../introduction.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../introduction.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="solution.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
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