var
  Form1: TForm1;
  zwischenerg: double;
  operation: integer;

implementation

{$R *.dfm}

procedure TForm1.FormShow(Sender: TObject);
begin
edit1.SetFocus;
end;

procedure TForm1.SpeedButton0Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton0.caption;
end;

procedure TForm1.SpeedButton1Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton1.caption;
end;

procedure TForm1.SpeedButton2Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton2.caption;
end;

procedure TForm1.SpeedButton3Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton3.caption;
end;

procedure TForm1.SpeedButton4Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton4.caption;
end;

procedure TForm1.SpeedButton5Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton5.caption;
end;

procedure TForm1.SpeedButton6Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton6.caption;
end;

procedure TForm1.SpeedButton7Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton7.caption;
end;

procedure TForm1.SpeedButton8Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton8.caption;
end;

procedure TForm1.SpeedButton9Click(Sender: TObject);
begin
edit1.Text:=edit1.Text+speedbutton9.caption;
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
begin
edit1.Text:='';
edit1.SetFocus;
end;

procedure TForm1.SpeedButton10Click(Sender: TObject);
begin
zwischenerg:=strtofloat(edit1.Text);
operation:=1;
edit1.Text:='';
edit1.setfocus;
end;

procedure TForm1.SpeedButton11Click(Sender: TObject);
begin
zwischenerg:=strtofloat(edit1.Text);
operation:=2;
edit1.Text:='';
edit1.setfocus;
end;

procedure TForm1.SpeedButton12Click(Sender: TObject);
begin
zwischenerg:=strtofloat(edit1.Text);
operation:=3;
edit1.Text:='';
edit1.setfocus;
end;

procedure TForm1.SpeedButton13Click(Sender: TObject);
begin
zwischenerg:=strtofloat(edit1.Text);
operation:=4;
edit1.Text:='';
edit1.setfocus;
end;

procedure TForm1.SpeedButtongleichClick(Sender: TObject);
begin
case operation of
1: edit1.Text:=floattostr(zwischenerg+strtofloat(edit1.text));
2: edit1.Text:=floattostr(zwischenerg-strtofloat(edit1.text));
3: edit1.Text:=floattostr(zwischenerg*strtofloat(edit1.text));
4: begin
    if strtofloat(edit1.text)=0 then begin
    showmessage('Division durch Null nicht teilbar');
    edit1.Text:='';
    zwischenerg:=0;
    end
    else
    edit1.Text:=floattostr(zwischenerg/strtofloat(edit1.text));
    end;

end;
end;
procedure TForm1.SpeedButton14Click(Sender: TObject);
begin
edit1.text:='';
end;

procedure TForm1.SpeedbuttonbackClick(Sender: TObject);
var hilf:string;

begin
hilf:=edit1.text;
Delete(hilf, length(edit1.Text), 1);
edit1.Text:=hilf;
end;

procedure TForm1.SpeedButton15Click(Sender: TObject);
begin
zwischenerg:=strtofloat(edit1.text);
edit1.text:=floattostr(1/zwischenerg);
end;

procedure TForm1.SpeedButtonkommaClick(Sender: TObject);
var anzahl:integer;
begin
edit1.Text:=edit1.Text+',';
anzahl:=1;
end;

end.