27 Time library [time]

27.8 The civil calendar [time.cal]

27.8.16 Class year_­month_­weekday [time.cal.ymwd] Overview [time.cal.ymwd.overview]

namespace std::chrono {
  class year_month_weekday {
    chrono::year            y_;         // exposition only
    chrono::month           m_;         // exposition only
    chrono::weekday_indexed wdi_;       // exposition only

    year_month_weekday() = default;
    constexpr year_month_weekday(const chrono::year& y, const chrono::month& m,
                                 const chrono::weekday_indexed& wdi) noexcept;
    constexpr year_month_weekday(const sys_days& dp) noexcept;
    constexpr explicit year_month_weekday(const local_days& dp) noexcept;

    constexpr year_month_weekday& operator+=(const months& m) noexcept;
    constexpr year_month_weekday& operator-=(const months& m) noexcept;
    constexpr year_month_weekday& operator+=(const years& y)  noexcept;
    constexpr year_month_weekday& operator-=(const years& y)  noexcept;

    constexpr chrono::year            year()            const noexcept;
    constexpr chrono::month           month()           const noexcept;
    constexpr chrono::weekday         weekday()         const noexcept;
    constexpr unsigned                index()           const noexcept;
    constexpr chrono::weekday_indexed weekday_indexed() const noexcept;

    constexpr          operator sys_days()   const noexcept;
    constexpr explicit operator local_days() const noexcept;
    constexpr bool ok() const noexcept;
year_­month_­weekday represents a specific year, month, and weekday of the month.
year_­month_­weekday is a field-based time point with a resolution of days.
year_­month_­weekday supports years- and months-oriented arithmetic, but not days-oriented arithmetic.
For the latter, there is a conversion to sys_­days, which efficiently supports days-oriented arithmetic.
— end note
year_­month_­weekday meets the Cpp17EqualityComparable (Table 25) requirements.
year_­month_­weekday is a trivially copyable and standard-layout class type.