unit Unit1;

interface

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

type
  TForm3 = class(TForm)
    But7: TButton;
    But4: TButton;
    But1: TButton;
    But0: TButton;
    But8: TButton;
    But5: TButton;
    But2: TButton;
    Butdot: TButton;
    But9: TButton;
    But6: TButton;
    But3: TButton;
    Buteq: TButton;
    Butmult: TButton;
    Butdiv: TButton;
    Butplus: TButton;
    Butminus: TButton;
    Butsqrt: TButton;
    Button1: TButton;
    Butdel: TButton;
    Edit1: TEdit;
    Butdivx: TButton;
    Butsquare: TButton;
    Button4: TButton;
    Butxy: TButton;
    Edit2: TEdit;
    procedure But1Click(Sender: TObject);
    procedure But2Click(Sender: TObject);
    procedure But3Click(Sender: TObject);
    procedure But0Click(Sender: TObject);
    procedure But4Click(Sender: TObject);
    procedure But5Click(Sender: TObject);
    procedure But6Click(Sender: TObject);
    procedure But7Click(Sender: TObject);
    procedure But8Click(Sender: TObject);
    procedure But9Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure ButplusClick(Sender: TObject);
    procedure ButminusClick(Sender: TObject);
    procedure ButdivClick(Sender: TObject);
    procedure ButmultClick(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure ButsquareClick(Sender: TObject);
    procedure ButdivxClick(Sender: TObject);
    procedure ButsqrtClick(Sender: TObject);
    procedure ButeqClick(Sender: TObject);
    procedure operation(op:char);
    procedure dig(dig:integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form3: TForm3;
  op:char;
  i:integer;
  dig1,dig2,dig3:real;

implementation

{$R *.dfm}

procedure TForm3.But0Click(Sender: TObject);
begin
dig(0);
end;

procedure TForm3.But1Click(Sender: TObject);
begin
dig(1);
end;

procedure TForm3.But2Click(Sender: TObject);
begin
dig(2);
end;

procedure TForm3.But3Click(Sender: TObject);
begin
dig(3);
end;

procedure TForm3.But4Click(Sender: TObject);
begin
dig(4);
end;

procedure TForm3.But5Click(Sender: TObject);
begin
dig(5);
end;

procedure TForm3.But6Click(Sender: TObject);
begin
dig(6);
end;

procedure TForm3.But7Click(Sender: TObject);
begin
dig(7);
end;

procedure TForm3.But8Click(Sender: TObject);
begin
dig(8);
end;

procedure TForm3.But9Click(Sender: TObject);
begin
dig(9);
end;

procedure TForm3.ButdivClick(Sender: TObject);
begin
operation('/');
end;

procedure TForm3.ButdivxClick(Sender: TObject);
begin
operation('\');
end;

procedure TForm3.ButeqClick(Sender: TObject);
begin
 if edit1.Text<>'' then  dig2:=strtofloat(edit1.text);
 if op='+' then dig3 := dig1 + dig2;
 if op='-' then dig3:=dig1 - dig2;
 if op='*' then dig3:=dig1 * dig2;
 if op='/' then dig3:=dig1 / dig2;

{*    case op of
    '+':dig3 := dig1 + dig2;
    '-':dig3:=dig1-dig2;
    '*':dig3:=dig1*dig2;
    '/':dig3:=dig1/dig2;
    end ;
*}
Edit1.Text:=FloatToStr(dig3);
end;

procedure TForm3.ButminusClick(Sender: TObject);
begin
operation('-');
end;

procedure TForm3.ButmultClick(Sender: TObject);
begin
operation('*');
end;

procedure TForm3.ButplusClick(Sender: TObject);
begin
operation('+');
end;

procedure TForm3.ButsqrtClick(Sender: TObject);
begin
operation('s');
end;

procedure TForm3.ButsquareClick(Sender: TObject);
begin
operation('^');
end;

procedure TForm3.Button1Click(Sender: TObject);
begin
Edit1.Clear;
end;

procedure TForm3.Button4Click(Sender: TObject);
begin
operation('_');
end;

procedure TForm3.dig(dig: integer);
begin
    edit1.Text:=edit1.Text+IntToStr(dig);
end;

procedure TForm3.operation(op: char);
begin
if Edit1.Text<>'' then
dig1:=StrToFloat(Edit1.Text);
op := op;
edit1.Clear;
end;
end.