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<H1 align="center">Boost.Regex</H1>
<H2 align="center">Unicode Regular Expressions.</H2>
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<P>There are two ways to use Boost.Regex with Unicode strings:</P>
<H3>Rely on wchar_t</H3>
<P>If your platform's wchar_t type can hold Unicode strings, <EM>and</EM> your
platform's C/C++ runtime correctly handles wide character constants (when
passed to std::iswspace std::iswlower etc), then you can use boost::wregex to
process Unicode. However, there are several disadvantages to this
approach:</P>
<UL>
<LI>
It's not portable: there's no guarantee on the width of wchar_t, or even
whether the runtime treats wide characters as Unicode at all, most Windows
compilers do so, but many Unix systems do not.</LI>
<LI>
There's no support for Unicode-specific character classes: [[:Nd:]], [[:Po:]]
etc.</LI>
<LI>
You can only search strings that are encoded as sequences of wide characters,
it is not possible to search UTF-8, or even UTF-16 on many platforms.</LI></UL>
<H3>Use a Unicode Aware Regular Expression Type.</H3>
<P>If you have the <A href="http://www.ibm.com/software/globalization/icu/">ICU
library</A>, then Boost.Regex can be <A href="install.html#unicode">configured
to make use of it</A>, and provide a distinct regular expression type
(boost::u32regex), that supports both Unicode specific character properties,
and the searching of text that is encoded in either UTF-8, UTF-16, or
UTF-32. See: <A href="icu_strings.html">ICU string class support</A>.</P>
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<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
04 Jan 2005
<!--webbot bot="Timestamp" endspan i-checksum="39359" --></p>
<p><i> Copyright John Maddock 2005</i></p>
<P><I>Use, modification and distribution are subject to the Boost Software License,
Version 1.0. (See accompanying file <A href="../../../LICENSE_1_0.txt">LICENSE_1_0.txt</A>
or copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)</I></P>
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