CLOCKS_PER_SEC
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header <time.h>
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|   #define CLOCKS_PER_SEC /*implementation defined*/  | 
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Expands to an expression (not necessarily a compile-time constant) of type clock_t equal to the number of clock ticks per second, as returned by clock(). 
[edit] Notes
POSIX defines CLOCKS_PER_SEC as one million, regardless of the actual precision of clock.
[edit] See also
|    returns raw processor clock time since the program is started  (function)  | |
|    process running time  (typedef)  | |
|   C++ documentation for CLOCKS_PER_SEC 
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