Dear all: if you #define BOOST_REGEX_MATCH_EXTRA, using char type will crash, but using string is well. Is that a bug? My environment is Windows XP, C++ Builder 2007. I show the example below: #define BOOST_REGEX_MATCH_EXTRA #include <boost/regex.hpp> #include <iostream> using namespace std; int main() { boost::regex reg("(.*)(\\d{2})"); boost::cmatch m; const char* text = "Note that I'm 31 years old, not 32."; if(boost::regex_search(text,m, reg)) { if (m[1].matched) std::cout << "(.*) matched: " << m[1].str() << '\n'; if (m[2].matched) std::cout << "Found the age: " << m[2] << '\n'; } } It will crash..... If don't #define BOOST_REGEX_MATCH_EXTRA, it works well. And the string type works both well. Maybe this is a bug? thank you for reading.