хочу сделать типа калькулятора ток на сложение вот код:
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
CalculateButton: TButton;
EndEdit: TEdit;
Label1: TLabel;
ResultEdit: TEdit;
Label2: TLabel;
Edit1: TEdit;
Label3: TLabel;
procedure CalculateButtonClick(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.CalculateButtonClick(Sender: TObject);
var
a:Integer;
b:Integer;
sum:Integer;
EndCount:Integer;

begin
if (a=0) and (b=0 ) and (sum=0) then EndCount
Sum:=a+b;


ResultEdit.Text:=IntToStr(Sum);
end;

end.