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< title > Unicode and Boost.Regex</ title >
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< div class = "titlepage" >< div >< div >< h2 class = "title" style = "clear: both" >
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< a name = "boost_regex.unicode" ></ a >< a class = "link" href = "unicode.html" title = "Unicode and Boost.Regex" > Unicode and Boost.Regex</ a >
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< p >
There are two ways to use Boost.Regex with Unicode strings:
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< h5 >
< a name = "boost_regex.unicode.h0" ></ a >
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< span class = "phrase" >< a name = "boost_regex.unicode.rely_on_wchar_t" ></ a ></ span >< a class = "link" href = "unicode.html#boost_regex.unicode.rely_on_wchar_t" > Rely
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on wchar_t</ a >
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< p >
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If your platform's < code class = "computeroutput" >< span class = "keyword" > wchar_t</ span ></ code > type
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can hold Unicode strings, and your platform's C/C++ runtime correctly handles
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wide character constants (when passed to < code class = "computeroutput" >< span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > iswspace</ span ></ code >
< code class = "computeroutput" >< span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > iswlower</ span ></ code > etc), then you can use < code class = "computeroutput" >< span class = "identifier" > boost</ span >< span class = "special" > ::</ span >< span class = "identifier" > wregex</ span ></ code >
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to process Unicode. However, there are several disadvantages to this approach:
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It's not portable: there's no guarantee on the width of < code class = "computeroutput" >< span class = "keyword" > wchar_t</ span ></ code > ,
or even whether the runtime treats wide characters as Unicode at all, most
Windows compilers do so, but many Unix systems do not.
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< li class = "listitem" >
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There's no support for Unicode-specific character classes: < code class = "computeroutput" >< span class = "special" > [[:</ span >< span class = "identifier" > Nd</ span >< span class = "special" > :]]</ span ></ code > , < code class = "computeroutput" >< span class = "special" > [[:</ span >< span class = "identifier" > Po</ span >< span class = "special" > :]]</ span ></ code >
etc.
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< li class = "listitem" >
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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.
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< h5 >
< a name = "boost_regex.unicode.h1" ></ a >
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< span class = "phrase" >< a name = "boost_regex.unicode.use_a_unicode_aware_regular_expr" ></ a ></ span >< a class = "link" href = "unicode.html#boost_regex.unicode.use_a_unicode_aware_regular_expr" > Use
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a Unicode Aware Regular Expression Type.</ a >
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</ h5 >
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< p >
If you have the < a href = "http://www.ibm.com/software/globalization/icu/" target = "_top" > ICU
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library</ a > , then Boost.Regex provides 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 class = "link" href = "ref/non_std_strings/icu.html" title = "Working With Unicode and ICU String Types" > ICU string class support</ a > .
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< div class = "copyright-footer" > Copyright © 1998-2013 John Maddock< p >
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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 > )
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