unit fibonacciunit;

interface

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

type
  TForm1 = class(TForm)
    Edit2: TEdit;
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;                   
    BitBtn1: TBitBtn;
    Label3: TLabel;
    BitBtn2: TBitBtn;
    Label4: TLabel;
    Label5: TLabel;
    Label6: TLabel;
    Label7: TLabel;
    edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure BitBtn2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
 var
  x,y:integer;
function fib(n:integer):integer;
begin
   case n of
    0:fib:=1;
    1:fib:=1;
    else
     fib:=fib(n-1)+fib(n-2);
     end;
   end;
 begin
   edit1.SetFocus;
   x:=strtoint(edit1.text);
   if x<0
   then showmessage('n不能為負數(shù)！')
   else
   begin
   y:=fib(x);
   edit2.text:=inttostr(y);
   end;

  end;




procedure TForm1.BitBtn2Click(Sender: TObject);
begin
edit1.Text:='';
edit2.Text:='';
edit1.SetFocus;

end;

end.