Represents a clock type that is based on the real-time clock of the system.
A clock type is used to obtain the current time as UTC. The type embodies an instantiation of duration and the class template time_point, and defines a static member function now() that returns the time.
A clock is monotonic if the value that is returned by a first call to now() is always less than or equal to the value that is returned by a subsequent call to now().
A clock is steady if it is monotonic and if the time between clock ticks is constant.
In this implementation, a system_clock is synonymous with a high_resolution_clock.
A synonym for duration<rep, period>.
A synonym for the type that is used to represent the tick period in the contained instantiation of duration.
A synonym for the type that is used to represent the number of clock ticks in the contained instantiation of duration.
A synonym for time_point<Clock, duration>, where Clock is a synonym for either the clock type itself or another clock type that is based on the same epoch and has the same nested duration type.