std::chrono::month_day_last::ok
From cppreference.com
                    
                                        
                    < cpp | 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()); }