CODEWITHSUNDEEP
c++boost
debonair
debonair

Reputation: 2593

how to get UTC time in micro-seconds with leap seconds

How to get UTC time in micro-seconds with leap seconds adjusted? I am using boost::universal_clock() 

 boost::posix_time::time_duration utc_time =
      boost::posix_time::microsec_clock::universal_time() -
      boost::posix_time::from_time_t(0);
  int64_t total_microsec = utc_time.total_microseconds();

But the result of this is same as 

std::chrono::time_point_cast<std::chrono::duration<int64_t, std::microseconds>>(
             std::chrono::system_clock::now())
      .time_since_epoch()
      .count();

which seems that boost is not adjusting leap seconds. However when I use C gmtime() I get different result:

  time_t mytime;

  struct tm *ptm;

  time(&mytime);  // Get local time in time_t

  ptm = gmtime(&mytime);  // Find out UTC time

  time_t utctime = mktime(ptm);  // Get UTC time as time_t

How to achieve it using boost library?

Upvotes: 1

Views: 495

Answers (1)

Howard Hinnant
Howard Hinnant

Reputation: 219518

Using Howard Hinnant's date/time library this is very easy:

#include "date/tz.h"
#include <iostream>

int
main()
{
    using namespace date;
    using namespace std;
    using namespace std::chrono;
    auto now = floor<microseconds>(utc_clock::now());
    cout << now << '\n';
    cout << now.time_since_epoch() << '\n';
    cout << clock_cast<system_clock>(now).time_since_epoch() << '\n';
}

This is a preview of the C++20 additions to <chrono>, but in namespace date.

utc_clock counts time since 1970-01-01 00:00:00 UTC including leap seconds. The clock_cast casts the time_point from this clock back to that of system_clock just for comparison purposes.

This program just output for me:

2019-08-10 00:19:04.388788
1565396371388788µs
1565396344388788µs

Some installation required.

Upvotes: 1

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