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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 processor
       time used is not available or its  value  cannot  be  represented,  the
       function returns the value (clock_t) -1.

CONFORMING TO

       C89,  C99,  POSIX.1-2001.   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  32-bit  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(2) (or another wait-type call).  Linux does not include the  times
       of  waited-for children in the value returned by clock().  The times(2)
       function, which explicitly returns  (separate)  information  about  the
       caller and its children, may be preferable.

SEE ALSO

       getrusage(2), times(2)

COLOPHON

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