CLOCK(3) Library Functions Manual CLOCK(3)

clockdetermine processor time used

Standard C Library (libc, -lc)

#include <time.h>

clock_t
clock(void);

The () function determines the amount of processor time used since the invocation of the calling process, measured in CLOCKS_PER_SECs of a second.

The clock() function returns the amount of time used unless an error occurs, in which case the return value is -1.

getrusage(2)

The clock() function conforms to ISO/IEC 9899:1990 (“ISO C90”) and Version 3 of the Single UNIX Specification (“SUSv3”) which requires CLOCKS_PER_SEC to be defined as one million.

June 4, 1993 macOS 15.2