Question

I am tring to use back-reference in boost version 1.44 but this don’t work for me.
this is my code:

 boost::regex_constants::syntax_option_type flags = boost::regex::extended;
 std::string regx="(aaa)bb\1";
 std::cout << "Expression:  \"" << regx << "\"\n";
 std::string str ="aaabbaaa";
 boost::regex e(regx,flags);
 if(boost::regex_match(text, what, e))//, boost::match_extra))
 {
   std::cout<<"found";
 } else
 {
   std::cout<<"not found";
 }

and this is my ouput:

   Expression:  "(aaa)bbb☺"
   ** not found **
   Press any key to continue . . .

what I am missing?
when I try std::string regx="(aaa)bb\\1" program crashed in boost::regex e(regx,flags);
mybe I miss some flag?

Answer 1

I fix this problem by chaning this row

   boost::regex_constants::syntax_option_type flags = boost::regex::extended;

to

   boost::regex_constants::syntax_option_type flags = boost::regex::bk_vbar;

and ofcourse use \\
and this work for me.

thanks