...
uses DateUtils;
...
var
fromdate, toDate : TDateTime;
begin
fromDate := EncodeDateTime(2000, 02, 26, 10, 0, 0, 0);
toDate := EncodeDateTime(2000, 02, 29, 9, 0, 0, 0);
ShowMessage('From date = '+DateTimeToStr(fromDate));
ShowMessage('To date = '+DateTimeToStr(toDate));
ShowMessage('Whole days difference = '+
IntToStr(DaysBetween(toDate, fromDate))+' days');
end;
...