Right way to get datetime year, month, ..., microseconds as integers

[JamesUnicomb]

I am working with utc times and am unable to extract the right times given input:

Is there a way to assume the input datetime is the UTC datetime?
`
double datetime_to_ymdhms(std::chrono::system_clock::time_point datetime) {
int day, hour, minute, second, microsecond;

    using namespace std::chrono;

	std::tm tm = {0,0,0,1,0,70}; tm.tm_isdst = 0;
	system_clock::time_point epoch = system_clock::from_time_t(std::mktime(&tm));

    system_clock::duration delta = datetime - epoch;

    days d = duration_cast<days>(delta);
	delta -= d;
	hours h = duration_cast<hours>(delta);
	delta -= h;
	minutes m = duration_cast<minutes>(delta);
	delta -= m;
	seconds s = duration_cast<seconds>(delta);
	delta -= s;
	microseconds ms = duration_cast<microseconds>(delta);
	microsecond = (int)delta.count() * (1e6) * ((double)(system_clock::duration::period::num) / (double)(system_clock::duration::period::den));

	day = d.count();
	hour = h.count();
	minute = m.count();
	second = s.count();

	printf("day: %d\n", day);
	printf("hour: %d\n", hour); # this hour has my local time zone in it
	printf("minute: %d\n", minute);
	printf("second: %d\n", second);
	printf("microsecond: %d\n", microsecond);

`