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clock(3) [ultrix man page]

clock(3)						     Library Functions Manual							  clock(3)

       clock - report CPU time used

       #include <time.h>

       clock_t clock ( )


       The routine returns the amount of CPU time (in microseconds) used since the first call to The time reported is the sum of the user and sys-
       tem times of the calling process and its terminated child processes for which it has executed or To determine  the  time  in  seconds,  the
       value returned by should be divided by the value of the macro CLOCKS_PER_SEC.

       The resolution of the clock is 16.667 milliseconds.

       The  value returned by is defined in microseconds for compatibility with systems that have CPU clocks with much higher resolution.  Because
       of this, the value returned will wrap around after accumulating only 2147 seconds of CPU time (about 36 minutes).

See Also
       wait(2), times(3), system(3)


Check Out this Related Man Page

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

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 processor 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 program; 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 approx- imately 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)
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