ultrix man page for clock

clock(3)						     Library Functions Manual							  clock(3)

Name
       clock - report CPU time used

Syntax
       #include <time.h>

       clock_t clock ( )

       CLOCKS_PER_SEC

Description
       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.

Restrictions
       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)

																	  clock(3)