std::chrono:: utc_clock

Defined in header <chrono>
class utc_clock ;		(since C++20)

The clock std::chrono::utc_clock is a Clock that represents Coordinated Universal Time (UTC). It measures time since 00:00:00 UTC, Thursday, 1 January 1970, including leap seconds.

utc_clock meets the Clock requirements. It does not meet the TrivialClock requirements unless the implementation can guarantee that now() does not throw an exception.

Time point family

Defined in namespace std::chrono
template < class Duration > using utc_time = std:: chrono :: time_point < std :: chrono :: utc_clock , Duration > ;		(since C++20)
using utc_seconds = utc_time < std:: chrono :: seconds > ;		(since C++20)

operator<< (std::chrono::utc_time) (C++20)	performs stream output on a utc_time (function template)
from_stream (std::chrono::utc_time) (C++20)	parses a utc_time from a stream according to the provided format (function template)
std::formatter <std::chrono::utc_time> (C++20)	formatting support for utc_time (class template specialization)

Member types

Member type	Definition
rep	signed arithmetic type representing the number of ticks in the clock's duration
period	a std::ratio type representing the tick period of the clock, in seconds
duration	std:: chrono :: duration < rep, period > , capable of representing negative durations
time_point	std:: chrono :: time_point < std :: chrono :: utc_clock >

Member constants

constexpr bool is_steady [static]

true if the time between ticks is always constant, i.e. calls to now() return values that increase monotonically even in case of some external clock adjustment, otherwise false (public static member constant)

Member functions

now [static]	returns a std::chrono::time_point representing the current point in time (public static member function)
to_sys [static]	converts utc_time to sys_time (public static member function)
from_sys [static]	converts sys_time to utc_time (public static member function)

Non-member functions

get_leap_second_info (C++20)

obtains leap second insertion information from a utc_time object (function template)

Helper classes

leap_second_info (C++20)

leap second insertion information (class)

Notes

The official UTC epoch is 1 January 1972. utc_clock uses 1 January 1970 instead to be consistent with std::chrono::system_clock .