std::chrono::weekday::weekday (3) Linux Manual Page

std::chrono::weekday::weekday – std::chrono::weekday::weekday

Synopsis

weekday() = default;
(1)(since C++ 20)

    explicit constexpr weekday(unsigned wd) noexcept;
(2)(since C++ 20)

    constexpr weekday(const std::chrono::sys_days &dp) noexcept;
(3)(since C++ 20)

    explicit constexpr weekday(const std::chrono::local_days &dp) noexcept;
(4)(since C++ 20)

Constructs a weekday object.
1) Default constructor leaves the weekday value uninitialized.
2) Constructs a weekday object holding the weekday value wd. If wd > 255, the value held is unspecified.
3) Constructs a weekday object representing the day of the week dp corresponds to. This constructor defines an implicit conversion from std::chrono::sys_days to weekday.
4) Constructs a weekday object representing the day of the week dp corresponds to, as if by weekday(std::chrono::sys_days(dp.time_since_epoch())).