25 Time library [time]

25.9 Class template time_­of_­day [time.tod]

25.9.2 Hours precision [time.tod.hours]

namespace std::chrono {
  template<>
  class time_of_day<hours> {
  public:
    using precision = chrono::hours;

    time_of_day() = default;
    explicit constexpr time_of_day(chrono::hours since_midnight) noexcept;

    constexpr chrono::hours hours() const noexcept;

    explicit constexpr operator  precision()   const noexcept;
    constexpr          precision to_duration() const noexcept;

    constexpr void make24() noexcept;
    constexpr void make12() noexcept;
  };
}
1
#
[ Note
:
This specialization handles hours since midnight.
— end note
 ]
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explicit constexpr time_of_day(chrono::hours since_midnight) noexcept;
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Effects: Constructs an object of type time_­of_­day in 24-hour format corresponding to since_­midnight hours after 00:00:00.
3
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Ensures: hours() returns the integral number of hours since_­midnight is after 00:00:00.
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constexpr chrono::hours hours() const noexcept;
4
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Returns: The stored hour of *this.
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explicit constexpr operator precision() const noexcept;
5
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Returns: The number of hours since midnight.
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constexpr precision to_duration() const noexcept;
6
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Returns: precision{*this}.
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constexpr void make24() noexcept;
7
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Effects: If *this is a 12-hour time, converts to a 24-hour time.
Otherwise, no effects.
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constexpr void make12() noexcept;
8
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Effects: If *this is a 24-hour time, converts to a 12-hour time.
Otherwise, no effects.