https://svn.boost.org/trac10/ticket/12870 <p> If you execute the following code, "[ 4]" will be output, but right output is supposed to be "<a class="changeset" href="https://svn.boost.org/trac10/changeset/4" title="Tweak disclaimer formatting, again">[4]</a>". </p> <h3 class="section" id="SourceCode">Source Code</h3> <pre class="wiki">#include &lt;iostream&gt; #include &lt;boost/xpressive/xpressive.hpp&gt; using namespace std; namespace xp = boost::xpressive; int main() { xp::sregex rule2 = xp::skip(xp::_s)('(' &gt;&gt; (xp::s1= *xp::_d) &gt;&gt; ')'); xp::sregex rule1 = xp::skip(xp::_s)(rule2); xp::smatch match1; if (!xp::regex_match(string("( 4 )"), match1, rule1)) { cout &lt;&lt; "syntax error" &lt;&lt; endl; } else { auto&amp;&amp; match2 = *match1.nested_results().begin(); string text = match2[1]; cout &lt;&lt; "[" &lt;&lt; text &lt;&lt; "]" &lt;&lt; endl; } return 0; } </pre><h3 class="section" id="CompilationEnvironment">Compilation Environment</h3> <ul><li>[OS] centos 6.8 </li><li>[Compiler] g++ v4.9.3 </li><li>[Command Line] g++ -std=c++11 a.cpp </li><li>[Libs] boost-1.63.0 </li></ul><p> Thanks for Boost.Xpressive! </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/12870 Trac 1.4.3