std::chrono::year_month_weekday_last::ok

From cppreference.com
Date and time utilities
(C++11)
(C++11)
Clocks
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
Calendars
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
Time zones
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
C-style date and time
constexpr bool ok() const noexcept;
(since C++20)

Checks if this object represents a valid date. Since a year_month_weekday_last represents the last weekday of a particular month, it is valid as long as the year, month and weekday are valid.

Return value

year().ok() && month().ok() && weekday().ok()