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CLOCK(P)			    POSIX Programmer's Manual				 CLOCK(P)

NAME
       clock - report CPU time used

SYNOPSIS
       #include <time.h>

       clock_t clock(void);

DESCRIPTION
       The clock() function shall return the implementation's best approximation to the processor
       time used by the process since the beginning of an implementation-defined era related only
       to the process invocation.

RETURN VALUE
       To  determine  the time in seconds, the value returned by clock() should be divided by the
       value of the macro CLOCKS_PER_SEC.    CLOCKS_PER_SEC is	defined  to  be  one  million  in
       <time.h>.  If the processor time used is not available or its value cannot be represented,
       the function shall return the value ( clock_t)-1.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       In order to measure the time spent in a program, clock() should be called at the start  of
       the  program  and its return value subtracted from the value returned by subsequent calls.
       The value returned by clock() is defined for compatibility across systems that have clocks
       with  different	resolutions.  The  resolution  on  any	particular  system need not be to
       microsecond accuracy.

       The value returned by clock() may wrap around on some implementations.  For example, on	a
       machine with 32-bit values for clock_t, it wraps after 2147 seconds or 36 minutes.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       asctime()  , ctime() , difftime() , gmtime() , localtime() , mktime() , strftime() , strp-
       time() , time() , utime() , the Base Definitions volume of IEEE Std 1003.1-2001, <time.h>

COPYRIGHT
       Portions of this text are reprinted and	reproduced  in	electronic  form  from	IEEE  Std
       1003.1,	2003  Edition,	Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003					 CLOCK(P)
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