std::chrono::high_resolution_clock
<chrono>
Class std::chrono::high_resolution_clock represents the clock with the smallest tick period provided by the implementation. It may be an alias of std::chrono::system_clock or std::chrono::steady_clock , or a third, independent clock.
std::chrono::high_resolution_clock meets the requirements of TrivialClock.
[edit] Member types
rep
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>
time_point
std::chrono::time_point <std::chrono::high_resolution_clock>
[edit] Member constants
(public static member constant)
[edit] Member functions
(public static member function)
[edit] Notes
There has been some controversy around the use of high_resolution_clock. Howard Hinnant, who claims to have introduced high_resolution_clock to the language, stated in 2016 on the ISO C++ Standard - Discussion mailing list that he was in favor of deprecating it. His rationale was that, because the standard allows for it to be an alias for std::chrono::steady_clock or std::chrono::system_clock , its use adds uncertainty to a program without benefit. However, other participants in the thread spoke out its favor, for instance on the basis that, because neither std::chrono::steady_clock nor std::chrono::system_clock come with any particular resolution guarantees, high_resolution_clock serves a useful role by giving the vendor an opportunity to supply the platform's highest-resolution clock, when neither its std::chrono::steady_clock nor its std::chrono::system_clock would be that.
It is often just an alias for std::chrono::steady_clock or std::chrono::system_clock , but which one it is depends on the library or configuration. When it is a system_clock, it is not monotonic (e.g., the time can go backwards). For example, as of 2023, libstdc++ has it aliased to system_clock "until higher-than-nanosecond definitions become feasible"[1] , MSVC has it as steady_clock[2] , and libc++ uses steady_clock when the C++ standard library implementation supports a monotonic clock and system_clock otherwise[3] .