I have probably missed something in the doc that answers my query but I just can’t see it.
 
This is using Perl syntax.
 
I had a regex:
 
    ^(XXX_\d{3,3})_\d{3,3}$
 
It compiles OK but does not match anything in a regex_search. If I remove the parenthesis
 
    ^XXX_\d{3,3}_\d{3,3}$
 
I get matches. Any clues as to what I am missing?
 
 
Extract of regex related code lines:
 
        reg.regex = new boost::regex(reg.reg,boost::regex::perl | boost::regex::icase);
 
        boost::match_results<string::const_iterator> match;
        boost::match_flag_type flags = boost::match_default;
        std::string::const_iterator xstart, xend;
 
        xrc = boost::regex_search(xstart,xend,match,*((*rgi).regex),flags);
 
Larry