Search code examples
delphiexcelformatcurrencyrounding

How to get Delphi Currency Type to Round like Excel all the time?

I'm trying to get Delphi to Round like Excel but I can't. Here is the code:

procedure TForm1.Button1Click(Sender: TObject);
var
 s : string;
 c : currency;
begin
 c := 54321.245;
 s := '';
 s := s + Format('Variable: %m',[c]);
 s := s + chr(13);
 s := s + Format('   Literal: %m',[54321.245]);
 ShowMessage(s);
end;

Delphi Rounding

I'm using a currency variable that is set to 54321.245 and when I format this variable it rounds using Bankers Rounding. However, when I format the same value as a literal it rounds the way that Excel rounds.

I was expecting this to round to $54,321.25 whether it's formating a currency variable or a literal value. How can I make sure that Delphi rounds the same way as Excel every time?

Edit

The rounding I expect to see is as follows:  
54,321.245   = 54,321.25  
54,321.2449  = 54,321.24  
54,431.2499  = 54,421.25

I am only using literals to show the different ways Delphi rounds. I expect to use variables in the actual code.

Note:
If I change the variable from currency to extended it rounds correctly

Edit #2

Some have suggested that I do not have a clear understanding of my requirements, this is absolutely not true. I have a very clear understanding of my requirements, I'm obviously not doing a very good job of explaining them. The rounding method I want is two decimal places. When the deimal part has a thousandths value >= 0.005 I want it rounded to 0.01 the currency type offered by Delphi does not do this. I also tried this example using Microsoft SQL with a money datatype (which I assumed was the same as Delphi's currency) and SQL rounds it's money type the way I described.

  • SQL Money >= 0.005 = 0.01
  • Delphi Currency >= 0.005 := 0.00

Edit #3
Good Article: http://rvelthuis.de/articles/articles-floats.html
Possible Solution: http://rvelthuis.de/programs/decimals.html

Edit #4
Here is one of the solutions from the Embarcadero discussion 

function RoundCurrency(const Value: Currency): Currency;
var
  V64: Int64 absolute Result;
  Decimals: Integer;
begin
  Result := Value;
  Decimals := V64 mod 100;
  Dec(V64, Decimals);
  case Decimals of
    -99 .. -50 : Dec(V64, 100);
    50 .. 99 : Inc(V64, 100);
  end;
end;
Solution

  • If I understand you correctly, you are looking for this:

    function RoundTo2dp(Value: Currency): Currency;
begin
  Result := Trunc(Value*100+IfThen(Value>0, 0.5, -0.5))/100;
end;