B20.1 clock() function bug?

N8TM@aol.com N8TM@aol.com
Mon Feb 1 18:46:00 GMT 1999

In a message dated 2/1/99 4:39:45 PM Pacific Standard Time,
Brian.P.Kasper@notes.aero.org writes:

<< This makes sense, as when I checked K&R (as you suggested below,
 oops, shoulda done that first off), clock() is defined as
 "clock returns the processor time used by the program since the
 beginning of execution, or -1 if unavailable.  clock()/CLK_TCK
 is a time in seconds." >>
That must be the classic K&R.  Since we're getting historic, I'll note that
H&S 2 quotes CLK_TCK as "proposed ANSI" while H&S 3 drops all mention of
CLK_TCK and quotes CLOCKS_PER_SECOND as the "ANSI facility."

If you're interested in gettimeofday(), it appears to have 1 second resolution
in some of the gcc ports, but I have never seen a gcc where it didn't work at
least to that extent, although that removes any advantage over standard C time

I don't know whether there is any future in trying to get fractional second
real time in a portable way;  on both W95 and NT the file stamp times
sometimes run backwards by up to 2 seconds.  I do find it strange that Irix
Fortran doesn't fill in the milliseconds field in DATE_AND_TIME(), when
gettimeofday() does it fine, and, as a consequence, so does g77.

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