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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="string_algo.rationale"></a>Rationale</h2></div></div></div>
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<dt><span class="section"><a href="rationale.html#idm45928155822480">Locales</a></span></dt>
<dt><span class="section"><a href="rationale.html#string_algo.regex">Regular Expressions</a></span></dt>
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<a name="idm45928155822480"></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.
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<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.
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<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.
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<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.
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<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>)
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