Namespaces
Variants

std::chrono::month_day_last:: ok

From cppreference.net
C++
Date and time library
std::chrono::month_day_last
constexpr bool ok ( ) const noexcept ;
(since C++20)

Checks if the month object stored in * this is valid.

Return value

month ( ) . ok ( )

Example

Run this code 
#include <cassert>
#include <chrono>
int main()
{
    auto mdl{std::chrono::February/std::chrono::last};
    assert(mdl.ok());
    mdl = {std::chrono::month(42)/std::chrono::last};
    assert(!mdl.ok());
}