Convert C# DateTime to C++ std::chrono::system_clock::time_point -

i need, in c++/clr code, convert datetime coming c# c++ std::chrono::system_clock:time_point equivalent.

will code job os there better way ?

std::chrono::system_clock::time_point convertdatetime(datetime datetime) {     int32 unixtimestamp = (int32)(datetime.utcnow.subtract(new datetime(1970, 1, 1))).totalseconds;     std::chrono::system_clock::time_point ret = std::chrono::system_clock::from_time_t(unixtimestamp );      return ret; } 

i don't think code works, though don't have datetime available test (i'm not on windows). utcnow "static" function returns current expressed "the current utc time", means: time duration past 1970-01-01 00:00:00 utc. believe formulation independent of value of parameter datetime.

i recommend trafficking in terms of datetime.ticks number of 100-nanosecond ticks past 1900-01-01 00:00:00 utc utc defined proleptically.

using free, open source, header-only library, can find difference between datetime epoch , system_clock epoch in terms of 100-nanosecond ticks vs uses:

it first convenient define ticks 100-nanoseconds units:

using ticks = std::chrono::duration<std::int64_t,                  std::ratio_multiply<std::ratio<100>, std::nano>>; 

and convertdatetime can written:

std::chrono::system_clock::time_point convertdatetime(datetime datetime) {     using namespace date;     using namespace std::chrono;     return system_clock::time_point{ticks{datetime.ticks}                 - (sys_days{1970_y/jan/1} - sys_days{1900_y/jan/1})}; } 

if dislike idea of using this date library, can hard code magic constant in above function so:

std::chrono::system_clock::time_point convertdatetime(datetime datetime) {     using namespace std::chrono;     return system_clock::time_point{ticks{datetime.ticks - 22089888000000000}}; } 

either 1 of these gets system_clock::time_point exact same precision datetime (on vs).