Why is CLOCKS_PER_SEC not the actual number of clocks per second?

Question

I have just written this short C++ program to approximate the actual number of clock ticks per second.

#include 
#include 

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Answer 1

C99 standard

The only thing the C99 N1256 standard draft says about CLOCKS_PER_SEC is that:

CLOCKS_PER_SEC which expands to an expression with type clock_t (described below) that is the number per second of the value returned by the clock function

As others mention, POSIX sets it to 1 million, which limits the precision of this to 1 microsecond. I think this is just a historical value from days where the maximum CPU frequencies were measured in Mega Hertz.