std::chrono::month_weekday
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header  <chrono>
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|   class month_weekday;  | 
(since C++20) | |
The class month_weekday represents the n-th weekday of a specific month, of some yet to be specified year.
month_weekday is a TriviallyCopyable StandardLayoutType.
Member functions
  constructs a month_weekday (public member function)  | |
|    retrieves the stored month and weekday_indexed values   (public member function)  | |
|    checks whether the contained month and weekday_indexed are valid   (public member function)  | 
Nonmember functions
   compares two month_weekday objects  (function)  | |
   outputs a month_weekday into a stream  (function template)  |