[fpc-devel] Definition of the time-fration in a TDateTime before 30/12/1899

Marco van de Voort marcov at stack.nl
Mon May 22 11:18:41 CEST 2006


> On Mon, 22 May 2006, Bram Kuijvenhoven wrote:
> > This is really bad -- I supposed the TDateTime was a nice 'linear' mapping of 
> > time (which is much nicer for all kinds of calculations).
> 
> It is, but only for dates after 1899-12-30. God only knows why Microsoft
> picked this date.

Julian is 1900-1-1 noon iirc. The deviation comes from compability with
older products that did leapyear calculation for the year 1900 wrong (and
maybe more), needing to adjust the origin date.

The noon definition was also not very practical.



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