[DUG] DateTime Floating Point Errors.

[Rohit Gupta]

Add to that, the fact that no one is supposed to be over a 100 years 
old... just shows the stupidity of Borland Staff in using date this way. 
Not only do I have to correct for the rounding, I also have to correct 
it for dates earlier than 1899.  I have always had functions for floats 
that I use for dates too... The trick is to get everyone to remember 
this.  MIne are called Is_Zero (Arg) and Are_Equal (Arg1, Arg2).


Kyley Harris wrote:

>I wonder if anyone else has noticed this irritating rounding issue on datetimes.
>
>Bear in mind that this is not a useful answer is you care about
>historical dates. I only care about dates greater than the year 2000.
>
>Problem. When comparing an "empty date" (meaning Date = 0.0) delphi
>behaves differently on different computers meaning that my if
>varDateValue = 0.0 can return false a lot of the time. This is also
>the same when comparing Dates that have a zero time factor.
>
>on my computer, EncodeDate(1899,12,30) + EncodeTime(0,0,0,0) does not
>return 0.0, but something along the lines of zero + an infintesimal
>fraction that does not equal zero any more.
>
>I solve my problem with the following method of forcing a date when
>setting a date property.
>
>  if DateTimeValue < ZeroDateThreshold /* EncodeDate(1900,1,1) */  then
>  begin
>    result := 0.0;
>  end else
>  begin
>    result := RecodeMilliSecond(result,0);
>  end;
>
>This forces a removal of all these little tiny bits of rubbish on the
>end of my datetimes that occurs when I convert my string dates
>"yyyymmddhhnnsszzz" into real date etc.
>
>anyone got better ideas? if not.. hope this helps anyone else.
>
>
>
>--
>Kyley Harris
>Harris Software
>+64-9-8455274
>+64-21-671-821
>
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>
>  
>