clock(3C)




NAME

     clock - report CPU time used


SYNOPSIS

     #include <time.h>

     clock_t clock(void);


DESCRIPTION

     The clock() function returns the  amount  of  CPU  time  (in
     microseconds)  used  since  the first call to clock() in the
     calling process. The time reported is the sum  of  the  user
     and  system  times of the calling process and its terminated
     child processes for which it has executed the wait(2)  func-
     tion, the pclose(3C) function, or the system(3C) function.


RETURN VALUES

     Dividing the value  returned  by  clock()  by  the  constant
     CLOCKS_PER_SEC,  defined  in  the <time.h> header, will give
     the time in seconds.  If the process time used is not avail-
     able  or  cannot  be   represented,  clock returns the value
     (clock_t) -1.


USAGE

     The value returned by clock() 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).


ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|


SEE ALSO

     times(2), wait(2), popen(3C), system(3C), attributes(5)


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