23 General utilities library [utilities]

23.17 Time utilities [time]

23.17.7 Clocks [time.clock]

23.17.7.3 Class high_­resolution_­clock [time.clock.hires]

Objects of class high_­resolution_­clock represent clocks with the shortest tick period.
high_­resolution_­clock may be a synonym for system_­clock or steady_­clock.
namespace std::chrono {
  class high_resolution_clock {
  public:
    using rep        = unspecified;
    using period     = ratio<unspecified, unspecified>;
    using duration   = chrono::duration<rep, period>;
    using time_point = chrono::time_point<unspecified, duration>;
    static constexpr bool is_steady = unspecified;

    static time_point now() noexcept;
  };
}