clock

CLOCK(3)		  Linux Programmer’s Manual		     CLOCK(3)



NAME
       clock - Determine processor time

SYNOPSIS
       #include <time.h>

       clock_t clock(void);

DESCRIPTION
       The  clock()  function returns an approximation of processor time used
       by the program.

RETURN VALUE
       The value returned is the CPU time used so far as a  clock_t;  to  get
       the  number of seconds used, divide by CLOCKS_PER_SEC.  If the proces-
       sor time used is not available or its value cannot be represented, the
       function returns the value (clock_t)-1.

CONFORMING TO
       ANSI C.	POSIX requires that CLOCKS_PER_SEC equals 1000000 independent
       of the actual resolution.

NOTES
       The C standard allows for arbitrary values at the start	of  the	 pro-
       gram;  subtract the value returned from a call to clock() at the start
       of the program to get maximum portability.

       Note that  the  time  can  wrap	around.	  On  a	 32bit	system	where
       CLOCKS_PER_SEC equals 1000000 this function will return the same value
       approximately every 72 minutes.

       On several other implementations, the value returned by	clock()	 also
       includes the times of any children whose status has been collected via
       wait() (or another wait-type call).  Linux does not include the	times
       of  waited-for children in the value returned by clock().  The times()
       function, which explicitly returns (separate)  information  about  the
       caller and its children, may be preferable.

SEE ALSO
       getrusage(2), times(2)



GNU				  2002-06-14			     CLOCK(3)