<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Rationale</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="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../string_algo.html" title="Chapter 21. Boost String Algorithms Library"> <link rel="prev" href="../boost/algorithm/trim.html" title="Function template trim"> <link rel="next" href="env.html" title="Environment"> </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 href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="../boost/algorithm/trim.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../string_algo.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="env.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="string_algo.rationale"></a>Rationale</h2></div></div></div> <div class="toc"><dl> <dt><span class="section"><a href="rationale.html#id2653619">Locales</a></span></dt> <dt><span class="section"><a href="rationale.html#string_algo.regex">Regular Expressions</a></span></dt> </dl></div> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="id2653619"></a>Locales</h3></div></div></div> <p> Locales have a very close relation to string processing. They contain information about the character sets and are used, for example, to change the case of characters and to classify the characters. </p> <p> C++ allows to work with multiple different instances of locales at once. If an algorithm manipulates some data in a way that requires the usage of locales, there must be a way to specify them. However, one instance of locales is sufficient for most of the applications, and for a user it could be very tedious to specify which locales to use at every place where it is needed. </p> <p> Fortunately, the C++ standard allows to specify the <span class="emphasis"><em>global</em></span> locales (using static member function <code class="computeroutput">std:locale::global()</code>). When instantiating an <code class="computeroutput">std::locale</code> class without explicit information, the instance will be initialized with the <span class="emphasis"><em>global</em></span> locale. This implies, that if an algorithm needs a locale, it should have an <code class="computeroutput">std::locale</code> parameter defaulting to <code class="computeroutput">std::locale()</code>. If a user needs to specify locales explicitly, she can do so. Otherwise the <span class="emphasis"><em>global</em></span> locales are used. </p> </div> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="string_algo.regex"></a>Regular Expressions</h3></div></div></div> <p> Regular expressions are an essential part of text processing. For this reason, the library also provides regex variants of some algorithms. The library does not attempt to replace Boost.Regex; it merely wraps its functionality in a new interface. As a part of this library, regex algorithms integrate smoothly with other components, which brings additional value. </p> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"><p><small>Last revised: February 27, 2008 at 20:00:24 +0000</small></p></td> <td align="right"><div class="copyright-footer">Copyright © 2002-2004 Pavol Droba<p>Use, modification and distribution is subject to the Boost Software License, Version 1.0. (See accompanying file <code class="filename">LICENSE_1_0.txt</code> 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="../boost/algorithm/trim.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../string_algo.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="env.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>