Re: System.Time.Clock Design Issues

Ashley Yakeley wrote:

In article <4201AEFA.6070400@cl.cam.ac.uk>, Ben Rudiak-Gould wrote:

...

* time_t is TAI (atomic seconds since TAI epoch) and gmtime returns UTC (with leap seconds)

* time_t is UTC (atomic seconds since UTC epoch) and gmtime returns UTC (with leap seconds)

I don't understand. What actual number does gmtime return in each case?

In the second case it returns 1972-07-14 22:13:19, because there's a 86401-second day between then and 1970-01-01 00:00:00 UTC. In the first case I suppose it would return :09, because 1970-01-01 00:00:00 TAI is 10 seconds earlier than 1970-01-01 00:00:00 UTC, and to compensate gmtime would subtract 10 from the value passed in. Like I said I don't know if there are any systems like this. In fact I'm sure there aren't, now that I noticed that the libtai documentation says "This implementation of tai_now assumes that the time_t returned from the time function represents the number of TAI seconds since 1970-01-01 00:00:10 TAI." That :10 at the end is what I hadn't noticed. -- Ben