std::chrono::time_of_day<Duration>::make12, std::chrono::time_of_day<Duration>::make24
From cppreference.com
                    
                                        
                    < cpp | chrono | time of day
                    
                                                            
                    | constexpr void make12() noexcept; | (1) | |
| constexpr void make24() noexcept; | (2) | |
Changes the output format.
1) If the current output format is 24-hour, converts to 12-hour time. Otherwise no effects.
2) If the current output format is 12-hour, converts to 24-hour time. Otherwise no effects.
Notes
It is not possible to query the current output format.