Корректное округление чисел



Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

{
The function Round of the Delphi doesn't work
like it is usually expected.
The odd numbera are rounded down and the even numbers up.
Die Round Funktion in Delphi gibt normalerweise nicht
die erwartete Zahl zurьck.
Die ungeraden Zahlen werden abgerundet, die geraden aufgerundet
Example/ Beispiel:
x:= Round(17.5) = x = 18
x:= Round(12.5) = x = 12
}
function DoRound(const X: Extended): Int64;
begin
Result := 0;
if X0 then
Result := trunc(X + 0.5);
if Xthen
Result := trunc(X - 0.5);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
ShowMessage(FormatFloat('0.00', DoRound(17.5)));  // - 18 
ShowMessage(FormatFloat('0.00', DoRound(12.5)));  // - 13 
//This rounds every value to 0.05 steps 
//Rundet in 0.05 Schritten 
ShowMessage(FormatFloat('0.00', Round(17.22 / 0.05) * 0.05)); // - 17.20 
end;
{***Another function:***}
function RoundUp(Value: Extended): Int64;
procedure Set8087CW(NewCW: Word);
asm
MOV     Default8087CW,AX
FNCLEX
FLDCW   Default8087CW
end;
const
RoundUpCW = $1B32;
var
OldCW: Word;
begin
OldCW := Default8087CW;
try
Set8087CW(RoundUpCW);
Result := Round(Value);
finally
Set8087CW(OldCW);
end;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
ShowMessage(FormatFloat('0.00', RoundUp(19.32)));  // - 19 
end;

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