c++ - Most elegant way to combine chrono::time_point from hours, minutes, seconds etc -

i have "human readable" variables hours, minutes, seconds, day, month, year contains values corresponding names (let's have systemtime structure <windows.h>).
way found create chrono::time_point is:

systemtime systime = ...; // came source (file, network, etc. ) tm t; t.tm_sec = systime.wsecond; t.tm_min = systime.wminute; t.tm_hour = systime.whour; t.tm_mday = systime.wday; t.tm_mon = systime.wmonth - 1; t.tm_year = systime.wyear - 1900; t.tm_isdst = 0; std::chrono::system_clock::time_point datetime =     std::chrono::system_clock::from_time_t( mktime( & t ) ); 

first, lost milliseconds systemtime.
second, (mmm...) don't sort of conversion ))

could give more elegant way issue ?

using this open source, header-only library, can:

#include "date.h" #include <iostream>  struct systemtime {     int wmilliseconds;     int wsecond;     int wminute;     int whour;     int wday;     int wmonth;     int wyear; };  int main() {     systemtime systime = {123, 38, 9, 10, 8, 7, 2015};     std::chrono::system_clock::time_point datetime =         date::sys_days(date::year(systime.wyear)                       /date::month(systime.wmonth)                       /date::day(systime.wday))         + std::chrono::hours(systime.whour)         + std::chrono::minutes(systime.wminute)         + std::chrono::seconds(systime.wsecond)         + std::chrono::milliseconds(systime.wmilliseconds);     std::cout << datetime << '\n'; } 

which outputs:

2015-07-08 10:09:38.123000 

in "date.h", may have play around these macros things compile vs.:

#  define constdata const #  define constcd11  #  define constcd14 

with std-conforming c++14 compiler, these macros should set to:

#  define constdata constexpr #  define constcd11 constexpr  #  define constcd14 constexpr