https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64303
Bug ID: 64303 Summary: The regex_token_iterator's copy constructor creates an incorrect iterator Product: gcc Version: 5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: kariya_mitsuru at hotmail dot com Created attachment 34278 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34278&action=edit g++ -v Please see the following sample. ========================================== sample code ========================================== #include <iostream> #include <regex> #include <string> int main() { const std::string s(" 111 222 "); const std::regex re("\\w+"); std::sregex_token_iterator it1(s.begin(), s.end(), re), it2(it1), end; for (; it1 != end; ++it1) { std::cout << "range = (" << it1->first - s.begin() << ", " << it1->second - s.begin() << "), " "str = '" << it1->str() << '\'' << std::endl; } std::cout << std::endl; for (; it2 != end; ++it2) { std::cout << "range = (" << it2->first - s.begin() << ", " << it2->second - s.begin() << "), " "str = '" << it2->str() << '\'' << std::endl; } } ================================================================================================= ============================= output ============================= range = (2, 5), str = '111' range = (7, 10), str = '222' range = (488, 10), str = '' range = (7, 10), str = '222' ================================================================== cf. http://melpon.org/wandbox/permlink/Dbb2PcGdnNeNon2r Though the C++11 standard says nothing about the regex_token_iterator's copy constructor, I think that *it2 should be equal to *it1. So, the output should be ============================= output ============================= range = (2, 5), str = '111' range = (7, 10), str = '222' range = (2, 5), str = '111' range = (7, 10), str = '222' ================================================================== Note that the operator= is a same result. cf. http://melpon.org/wandbox/permlink/doxdyo4AfiFM6UMK