std::chrono::year_month_weekday::ok(3)

NAME
std::chrono::year_month_weekday::ok - std::chrono::year_month_weekday::ok

Synopsis
   constexpr bool ok() const noexcept; (since C++20)
   Checks if this year_month_weekday object represents a valid date.

Return value
   true if this year_month_weekday object represents a valid date, that is, year().ok()
   && month().ok() && weekday_indexed().ok() is true and there are at least index()
   weekday()s in the specified year and month. Otherwise false.

Example
// Run this code
 #include <cassert>
 #include <chrono>
 int main()
 {
     auto ymwdi{std::chrono::Wednesday[1]/1/2021};
     assert(ymwdi.ok());
     ymwdi = std::chrono::year(2021)/std::chrono::month(1)/std::chrono::Wednesday[42];
     assert(!ymwdi.ok());
 }