Boost C++ Libraries: Ticket #2750: regex backwar looking assertion https://svn.boost.org/trac10/ticket/2750 <p> The perl expression (?&lt;=.{3,3}).{6,6} passed in to boost regex results in Unmatched [ or [<sup> </sup></p> <p> ?&lt;= signifies a backward looking positive assertion so a pattern match should be returning 6 characters starting at offset 4 This works fine in perl. Any idea what part of the pattern is causing the issue? </p> <p> thanks </p> <p> Mark </p> en-us Boost C++ Libraries /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/2750 Trac 1.4.3 Steven Watanabe Thu, 12 Feb 2009 02:38:03 GMT component changed https://svn.boost.org/trac10/ticket/2750#comment:1 https://svn.boost.org/trac10/ticket/2750#comment:1 <ul> <li><strong>component</strong> <span class="trac-field-old">None</span> → <span class="trac-field-new">regex</span> </li> </ul> Ticket Steven Watanabe Thu, 12 Feb 2009 02:57:42 GMT owner changed https://svn.boost.org/trac10/ticket/2750#comment:2 https://svn.boost.org/trac10/ticket/2750#comment:2 <ul> <li><strong>owner</strong> changed from <span class="trac-author">Aaron Windsor</span> to <span class="trac-author">John Maddock</span> </li> </ul> <p> What compiler? It works for me with Visual Studio 2008 and Boost 1.36.0 </p> <pre class="wiki">#include &lt;boost/regex.hpp&gt; #include &lt;iostream&gt; int main() { boost::regex r("(?&lt;=.{3,3}).{6,6}"); std::cout &lt;&lt; boost::regex_search("...122340", r) &lt;&lt; std::endl; } </pre> Ticket anonymous Fri, 13 Feb 2009 16:45:13 GMT status changed; resolution set https://svn.boost.org/trac10/ticket/2750#comment:3 https://svn.boost.org/trac10/ticket/2750#comment:3 <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">worksforme</span> </li> </ul> <p> Works for me too, closing this for now, please reopen if you have a test case that demonstrates the issue with Boost-1.38. </p> <p> John Maddock </p> Ticket