std::chrono::year_month
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | Defined in header  <chrono> | ||
| class year_month; | (since C++20) | |
The class year_month represents a specific month of a specific year, but with an unspecified day. It is a field-based time point, with a resolution of std::chrono::months.
year_month is a TriviallyCopyable StandardLayoutType.
Member functions
| constructs a year_month(public member function) | |
| accesses the stored year and month (public member function) | |
| modifies the year_monthby some number of months or years(public member function) | |
| checks if this year_monthis valid(public member function) | 
Nonmember functions
| compares two year_monthobjects(function) | |
| performs arithmetic on year_month(function) | |
| outputs a year_monthinto a stream(function template) | |
| outputs a year_monthinto a stream according to the provided format(function template) | |
| parses a year_monthfrom a stream according to the provided format(function template) |