std::chrono::time_of_day::hours,std::chrono::time_of_day::minutes, (3) Linux Manual Page

std::chrono::time_of_day<Duration>::hours,std::chrono::time_of_day<Duration>::minutes, – std::chrono::time_of_day<Duration>::hours,std::chrono::time_of_day<Duration>::minutes,

Synopsis

             std::chrono::time_of_day<Duration>::subseconds
member of all specializations
constexpr std::chrono::hours hours() const noexcept;                            (1)
member of all specializations except time_of_day<std::chrono::hours>
constexpr std::chrono::minutes minutes() const noexcept;                        (2)
member only of the time_of_day<std::chrono::seconds> and
time_of_day<std::chrono::duration<Rep, Period>> specializations
constexpr std::chrono::seconds seconds() const noexcept;                        (3)
member only of the time_of_day<std::chrono::duration<Rep, Period>> partial
specialization
constexpr precision subseconds() const noexcept;                                (4)
Obtains the components of the stored "broken down" time.

Return value

Let since_midnight be the stored duration:
1) the integral number of hours since_midnight is after 00:00:00.
2) the integral number of minutes since_midnight is after (00:00:00 + hours()).
3) the integral number of seconds since_midnight is after (00:00:00 + hours() +
minutes()).
4) the integral number of fractional seconds since_midnight is after (00:00:00 +
hours() + minutes() + seconds()).