< cpp‎ | chrono
Defined in header <chrono>
class system_clock;
(since C++11)

Class std::chrono::system_clock represents the system-wide real time wall clock.

It may not be monotonic: on most systems, the system time can be adjusted at any moment. It is the only C++ clock that has the ability to map its time points to C-style time, and, therefore, to be displayed.

std::chrono::system_clock meets the requirements of TrivialClock.

The epoch of system_clock is unspecified, but most implementations use Unix Time (i.e., time since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970, not counting leap seconds).


[edit] 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::system_clock>

[edit] Member constants

constexpr bool is_steady
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)

[edit] Member functions

returns a std::chrono::time_point representing the current point in time
(public static member function) [edit]
converts a system clock time point to std::time_t
(public static member function) [edit]
converts std::time_t to a system clock time point
(public static member function) [edit]

[edit] See also

monotonic clock that will never be adjusted
the clock with the shortest tick period available