[Boost-users] convert separate year, month, day, hour, minute, secs, ms to milliseconds since epoch

Subject: [Boost-users] convert separate year, month, day, hour, minute, secs, ms to milliseconds since epoch
From: Victor Yankee (victor.whiskey.yankee_at_[hidden])
Date: 2019-03-03 20:45:17

I am using C++14 and boost 1.64.0 (could move to newest boost), and need to
convert date and time pieces to a single value for milliseconds since the
epoch. This is what I have:

int64_t msSinceEpoch(int year,int month,int day,int hour,int minute,int
second,int ms)
            {
            struct std::tm t;
            t.tm_sec    = second;
            t.tm_min    = minute;
            t.tm_hour   = hour;
            t.tm_mday   = day;
            t.tm_mon    = month-1;
            t.tm_year   = year-1900;
            t.tm_isdst  = 0;
            return (1000* timegm(&t))+ms; // is timegm cross-platform?
            }

Is there a better way? Could not figure out how to use boost::chrono :(
Something else?

Kind Regards,
Vic