# std::chrono::utc_clock

From cppreference.com
< cpp‎ | chrono

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.

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/chrono/utc_clock&oldid=161890"