https://svn.boost.org/trac10/ticket/11524 <pre class="wiki">The character u+100 is not found using the regex pattern[[:unicode:]]. Here sample : #include &lt;boost/regex.hpp&gt; #include &lt;iostream&gt; using namespace std; using namespace boost; int main() { wregex re(L"[[:unicode:]]"); wstring wstr=L"\u0100"; if(regex_match(wstr,re)) cout&lt;&lt;"Match "&lt;&lt;endl; else { cout&lt;&lt;"Not match"&lt;&lt;endl; } return 0; } 'Not match' is displayed. Proposed fix : --- boost_1_58_0\boost\regex\v4\regex_traits_defaults.hpp Sat Feb 14 15:22:25 2015 +++ boost_1_58_0new\boost\regex\v4\regex_traits_defaults.hpp Tue Aug 04 21:20:38 2015 @@ -51,7 +51,7 @@ // template &lt;class charT&gt; inline bool is_extended(charT c) -{ return c &gt; 256; } +{ return c &gt; 255; } inline bool is_extended(char) { return false; } </pre> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/11524 Trac 1.4.3 John Maddock Thu, 20 Aug 2015 08:11:34 GMT https://svn.boost.org/trac10/ticket/11524#comment:2 https://svn.boost.org/trac10/ticket/11524#comment:2 <ul> <li><strong>status</strong> <span class="trac-field-old">new</span> → <span class="trac-field-new">closed</span> </li> <li><strong>resolution</strong> → <span class="trac-field-new">fixed</span> </li> </ul> <p> Fixed in <a class="ext-link" href="https://github.com/boostorg/regex/commit/94c7d4a38ad4debb91391b17745e49c467de1bf3"><span class="icon">​</span>https://github.com/boostorg/regex/commit/94c7d4a38ad4debb91391b17745e49c467de1bf3</a> </p> Ticket