C Date and time utilities
From cppreference.com
                    
                                        
                    
                    
                                                            
                    Functions
|   Defined in header  
<ctime>  | |
 Time manipulation | |
|    computes the difference between times  (function)  | |
|    returns the current time of the system as time since epoch  (function)  | |
|    returns raw processor clock time since the program is started  (function)  | |
|    (since C++17)  | 
   returns the calendar time based on a given time base   (function)  | 
 Format conversions | |
   converts a tm object to a textual representation (function)  | |
   converts a time_t object to a textual representation (function)  | |
   converts a tm object to custom textual representation (function)  | |
   converts a tm object to custom wide string textual representation  (function)  | |
|    converts time since epoch to calendar time expressed as Universal Coordinated Time  (function)  | |
|    converts time since epoch to calendar time expressed as local time  (function)  | |
|    converts calendar time to time since epoch  (function)  | |
Constants
|    number of processor clock ticks per second  (macro constant)  | 
Types
|    calendar time type  (class)  | |
|    time since epoch type  (typedef)  | |
|    process running time  (typedef)  | |
|    (since C++17)  | 
   time in seconds and nanoseconds   (struct)  |