Variant and TDateTime

check here. this should help

http://www.delphibasics.co.uk/RTL.asp?Name=Variant

That link didn't work for me... anyway, you can check what type a variant holds, by using the VarType function... see the example below.

regards
Hypo

procedure TForm1.Button1Click(Sender: TObject);
var aVar : Variant;
    aDateTime : TDateTime;
    aDouble : Double;
begin
  aVar := aDateTime;
  Case VarType(aVar) of
    varDate: ShowMessage('Variant is a date');
    varDouble: ShowMessage('Variant is a double');
    else ShowMessage('Variant is of some other type');
  end;
 
  aVar := aDouble;
  Case VarType(aVar) of
    varDate: ShowMessage('Variant is a date');
    varDouble: ShowMessage('Variant is a double');
    else ShowMessage('Variant is of some other type');
  end;
end;

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case VarType(Param) of
  varDate: ShowMessage('Date : ' + FormatDateTime('dd/mm/yyyy hh:nn:ss', VarToDateTime(Param)));
  varDouble: ShowMessage('Double: ' + FloatToStr(Param));
end;

The VarType "varDouble" could not be a valid TDateTime but a normal Double value.

how did you get the value ?
that will determine your approach !

ISIGest: Sorry, but I really don't understand your comment... It didn't work for you?  you got a runtime error? Can you post some of your code, with an explaination of what you are trying to do, and what results you'd expect if it was working?

Ok...sorry...
If I test the variant variable with a VarType() function, the result can be varDouble if the variant value is a TDateTime like "15/05/2009 10.34" (in Double value format = 39948,440278), but it can be also a normal Double value like 350,25 or other value like 8540,69.
Ok, now how i can check if this value is a "valid" Double for a valid TDateTime?

Thanks.