Determines the CPU time (in 10-millisecond units) used since the
    beginning of the process. The time reported is the sum of the
    user and system times of the calling process and any terminated
    child processes for which the calling process has executed wait
    or system.

    Format

      #include  <time.h>

      clock_t clock  (void);

1 - Description

    The value returned by the clock function must be divided by the
    value of the CLK_TCK, as defined in the standard header file
    <time.h>, to obtain the time in seconds.

    The type clock_t is defined in the <time.h> header file as
    follows:

    typedef long int clock_t;

    Only the accumulated times for child processes running a C main
    program or a program that calls VAXC$CRTL_INIT or DECC$CRTL_INIT
    are included.

    A typical usage of the clock function is to call it after a
    program does its initial setup, and then again after the program
    executes the code to be timed. Then subtract the two values to
    give elapsed CPU time.

2 - Return Values

    n                  The processor time used.
    -1                 Indicates that the processor time used is not
                       available.