25 Time library [time]

25.9 Class template time_­of_­day [time.tod]

25.9.5 Sub-second precision [time.tod.subsecond]

namespace std::chrono {
  template<class Rep, class Period>
  class time_of_day<duration<Rep, Period>> {
  public:
    using precision = duration<Rep, Period>;

    time_of_day() = default;
    explicit constexpr time_of_day(precision since_midnight) noexcept;

    constexpr chrono::hours     hours()      const noexcept;
    constexpr chrono::minutes   minutes()    const noexcept;
    constexpr chrono::seconds   seconds()    const noexcept;
    constexpr precision subseconds() const noexcept;

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

    constexpr void make24() noexcept;
    constexpr void make12() noexcept;
  };
}
1
#
This specialization shall not exist unless treat_­as_­floating_­point_­v<Rep> is false and duration<Rep, Period> is not convertible to seconds.
[ Note
:
This specialization handles hours, minutes, seconds, and fractional seconds since midnight.
Typical uses are with milliseconds, microseconds and nanoseconds.
— end note
 ]
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explicit constexpr time_of_day(precision since_midnight) noexcept;
2
#
Effects: Constructs an object of type time_­of_­day in 24-hour format corresponding to since_­midnight fractional seconds after 00:00:00.
3
#
Ensures: hours() returns the integral number of hours since_­midnight is after 00:00:00.
minutes() returns the integral number of minutes since_­midnight is after (00:00:00 + hours()).
seconds() returns the integral number of seconds since_­midnight is after (00:00:00 + hours() + minutes()).
subseconds() returns the integral number of fractional seconds since_­midnight is after (00:00:00 + hours() + minutes() + seconds()).
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constexpr chrono::hours hours() const noexcept;
4
#
Returns: The stored hour of *this.
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constexpr chrono::minutes minutes() const noexcept;
5
#
Returns: The stored minute of *this.
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constexpr chrono::seconds seconds() const noexcept;
6
#
Returns: The stored second of *this.
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constexpr duration<Rep, Period> subseconds() const noexcept;
7
#
Returns: The stored subsecond of *this.
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explicit constexpr operator precision() const noexcept;
8
#
Returns: The number of subseconds since midnight.
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constexpr precision to_duration() const noexcept;
9
#
Returns: precision{*this}.
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constexpr void make24() noexcept;
10
#
Effects: If *this is a 12-hour time, converts to a 24-hour time.
Otherwise, no effects.
🔗
constexpr void make12() noexcept;
11
#
Effects: If *this is a 24-hour time, converts to a 12-hour time.
Otherwise, no effects.