Defined in header
#define CLOCKS_PER_SEC /*implementation defined*/
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().
CLOCKS_PER_SEC as one million, regardless of the actual precision of clock.
Until standardized as
CLOCKS_PER_SEC in C89, this macro was sometimes known by its IEEE std 1003.1-1988 name
CLK_TCK: that name was not included in C89 and was removed from POSIX itself in 1996 over ambiguity with
_SC_CLK_TCK, which gives number of clocks per second for the function times()).
- C11 standard (ISO/IEC 9899:2011):
- 7.27.1/2 Components of time (p: 388)
- C99 standard (ISO/IEC 9899:1999):
- 7.23.1/2 Components of time (p: 338)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.12.1 Components of time
 See also
| returns raw processor clock time since the program is started
| processor time since era type
C++ documentation for CLOCKS_PER_SEC