delphi 四舍五入保留一位或两位小数写法，后面参数为保留小数点位数

function RoundFloat(f: double; i: integer): double;
var
  s: string;
  ef: Extended;
begin
  if f = 0 then begin
    Result := 0;
    Exit;
  end;
  s := '#.' + StringOfChar('0', i);
  if s = '#.' then s := '#';
  ef := StrToFloat(FloatToStr(f)); //防止浮点运算的误差
  result := StrToFloat(FormatFloat(s, ef));
end;

//调用
procedure TForm1.Button1Click(Sender: TObject);
begin
Edit2.Text:=FloatToStr(RoundFloat(StrToFloat(Edit1.Text),2));
end;