std::chrono::month_day:: ok

From cppreference.com
Utilities library
General utilities
Relational operators (deprecated in C++20)
constexpr bool ok ( ) const noexcept ;
(since C++20)

Determines whether this month_day stores a valid month-day combination.

The combination is valid if month() represents a valid month ( month ( ) . ok ( ) == true ), unsigned { day ( ) } >= 1 , and unsigned { day ( ) } <= D , where D is the number of days in the month represented by month() . The number of days in February is considered to be 29.

Return value

true if the month and day combination is valid, otherwise false.

Example

#include <chrono>
#include <iostream>
 
int main()
{
    std::cout << std::boolalpha;
 
    constexpr auto md1{std::chrono::July/15};
    std::cout << (md1.ok()) << ' ';
    constexpr std::chrono::month_day md2{std::chrono::month(14), std::chrono::day(42)};
    std::cout << (md2.ok()) << ' ';
    constexpr auto md3{std::chrono::February/29};
    std::cout << (md3.ok()) << '\n';
}

Output:

true false true