std::chrono::year::ok (3) Linux Manual Page

std::chrono::year::ok – std::chrono::year::ok

Synopsis

constexpr bool ok() const noexcept; (since C++20)
Checks if the year value stored in *this is in the valid range, i.e., [-32767, 32767].

Return value

true if the year value stored in *this is in the range [-32767, 32767]. Otherwise false.