constexpr std::chrono::weekday_indexed operator[](unsigned index) const noexcept;

constexpr std::chrono::weekday_last operator[](std::chrono::last_spec) const noexcept;

1) Constructs a weekday_indexed from *this and index. The result represents the index-th weekday in some yet-to-be-specified month. If index is not in the range [1, 5] or if !ok() the values held in the result is unspecified.

2) Constructs a weekday_last from *this. The result represents the last weekday in some yet-to-be-specified month.

1) std::chrono::weekday_indexed(*this, index)

2) std::chrono::weekday_last(*this)