Time zone: the next generation (future transitions)

Olson, Arthur David (NIH/NCI) olsona at dc37a.nci.nih.gov
Tue Mar 8 18:44:50 UTC 2005

The Gregorian calendar cycles every 400 years: January 1 fell on a [Saturday] in
2000, and will do so again in 2400.
In a traditional-zic approach, we could store 400 (or more) years worth of
future transitions; stuff beyond that could be handled at run time.
For example, a localtime call would, for far future times: cast out 400
years worth of seconds at a time to get to the near future (remembering how
many years worth of seconds had been cast out); convert the resulting time_t
value; and add the cast-off number of years to the resulting time_t value.
We'd of course need to check at run time to verify that this was the right


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