Hello, I tried the below code: #include <boost/date_time.hpp> #include <boost/date_time/posix_time/ptime.hpp> #include <iostream> using namespace boost::posix_time; int main() { std::string _format1 = "%Y-%m-%d %H:%M:%S"; std::string _format2 = "%Y-%m-%e %H:%M:%S"; std::string teststring = "2010-09-10 10:01:01"; ptime time1, time2; time_input_facet facet1(_format1, 1); time_input_facet facet2(_format2, 1); std::stringstream ss1(teststring); std::stringstream ss2(teststring); ss1.imbue(std::locale(ss1.getloc(), &facet1)); ss1 >> time1; ss2.imbue(std::locale(ss2.getloc(), &facet2)); ss2 >> time2; std::cout << "Time1: " << time1 << std::endl; std::cout << "Time2: " << time2 << std::endl; return 0; } The output is: Time1: 2010-Sep-10 10:01:01 Time2: not-a-date-time Howto fix the issue for the format using "%e"? Thanks!