unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    GroupBox1: TGroupBox;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    Button6: TButton;
    Button7: TButton;
    Button8: TButton;
    Button9: TButton;
    Button10: TButton;
    Button11: TButton;
    Button12: TButton;
    Button13: TButton;
    Button14: TButton;
    Button15: TButton;
    Button16: TButton;
    Button17: TButton;
    Button18: TButton;
    Button19: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
    procedure Button6Click(Sender: TObject);
    procedure Button7Click(Sender: TObject);
    procedure Button8Click(Sender: TObject);
    procedure Button9Click(Sender: TObject);
    procedure Button10Click(Sender: TObject);
    procedure Button11Click(Sender: TObject);
    procedure Button12Click(Sender: TObject);
    procedure Button13Click(Sender: TObject);
    procedure Button14Click(Sender: TObject);
    procedure Button16Click(Sender: TObject);
    procedure Button15Click(Sender: TObject);
    procedure Button17Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button18Click(Sender: TObject);
    procedure Button19Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  tag,sign:integer;
  s1,s2,s3:real;
  s:string;
implementation

{$R *.dfm}


procedure TForm1.Button1Click(Sender: TObject);

   
begin
 edit1.Text  :='0';
 tag:=0;

end;
procedure TForm1.Button3Click(Sender: TObject);
begin
close;
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
 if tag=0 then
 edit1.text:='1'
 else
 edit1.text:=edit1.Text +'1';
 tag:=tag+1;
end;

procedure TForm1.Button5Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='2'
 else
 edit1.text:=edit1.Text +'2';
 tag:=tag+1;
end;

procedure TForm1.Button6Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='3'
 else
 edit1.text:=edit1.Text +'3';
 tag:=tag+1;
end;

procedure TForm1.Button7Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='4'
 else
 edit1.text:=edit1.Text +'4';
 tag:=tag+1;
end;

procedure TForm1.Button8Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='5'
 else
 edit1.text:=edit1.Text +'5';
 tag:=tag+1;
end;

procedure TForm1.Button9Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='6'
 else
 edit1.text:=edit1.Text +'6';
 tag:=tag+1;
end;

procedure TForm1.Button10Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='7'
 else
 edit1.text:=edit1.Text +'7';
 tag:=tag+1;
end;

procedure TForm1.Button11Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='8'
 else
 edit1.text:=edit1.Text +'8';
 tag:=tag+1;
end;

procedure TForm1.Button12Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='9'
 else
 edit1.text:=edit1.Text +'9';
 tag:=tag+1;
end;

procedure TForm1.Button13Click(Sender: TObject);
begin
if tag=0 then
 edit1.text:='0'
 else
 begin
 edit1.text:=edit1.Text +'0';
 tag:=tag+1;
 end;
end;

procedure TForm1.Button14Click(Sender: TObject);
begin
 edit1.Text :=inttostr(-(strtoint(edit1.Text)));
end;

procedure TForm1.Button16Click(Sender: TObject);
begin
 s1:=strtofloat(edit1.Text);
 sign:=1;
 tag:=0;
end;

procedure TForm1.Button15Click(Sender: TObject);
begin
if sign=4 then
  begin
  s2:=strtofloat(edit1.Text );
  s3:=s1/s2;
  edit1.Text :=floattostr(s3);
  end;
  if sign=1 then
  begin
  s2:=strtofloat(edit1.Text );
  s3:=s1+s2;
  edit1.Text :=floattostr(s3);
  end;
  if sign=2 then
  begin
  s2:=strtofloat(edit1.Text );
  s3:=s1-s2;
  edit1.Text :=floattostr(s3);
  end;
   if sign=3 then
  begin
  s2:=strtofloat(edit1.Text );
  s3:=s1*s2;
  edit1.Text :=floattostr(s3);
  end;

end;

procedure TForm1.Button17Click(Sender: TObject);
begin
  s1:=strtofloat(edit1.Text);
 sign:=2;
 tag:=0;
end;

procedure TForm1.Button2Click(Sender: TObject);
var
a:integer;
begin
  a:=length(edit1.text);
  edit1.Text :=copy(edit1.Text,1,a-1);
  tag:=tag-1;
end;

procedure TForm1.Button18Click(Sender: TObject);
begin
s1:=strtofloat(edit1.Text);
 sign:=3;
 tag:=0;
end;

procedure TForm1.Button19Click(Sender: TObject);
begin
s1:=strtofloat(edit1.Text);
 sign:=4;
 tag:=0;
end;

end.