unit1.~pas

这个是一个实例

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    BitBtn1: TBitBtn;
    BitBtn2: TBitBtn;
    procedure BitBtn2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Edit1Change(Sender: TObject);
    procedure Edit2Change(Sender: TObject);
    procedure BitBtn1Click(Sender: TObject);
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.BitBtn2Click(Sender: TObject);
begin
close;//关闭窗体
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
Edit1.text:='';     //创建窗体时，让编辑框为空
Edit2.text:='';
BitBtn1.Enabled:=false;
end;

procedure TForm1.Edit1Change(Sender: TObject);
begin    //当编辑框Edit1中为6个字符时，输入焦点跳到Edit2
if length(edit1.Text)=6 then
form1.FocusControl(Edit2);
end;

procedure TForm1.Edit2Change(Sender: TObject);
begin  //如果两个编辑框中的输入是正确的，Ok按钮被被激活并获得输入焦点
if (Edit2.Text='123456') and (Edit1.Text='950755') then
begin
  bitbtn1.Enabled:=true;
  form1.FocusControl(bitBtn1);
end;
end;

procedure TForm1.BitBtn1Click(Sender: TObject);
begin
showmessage('您通过了身份验证。');
close;
end;

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin　//限制编辑框的输入，只接收数字
if not (key in['0'..'9',#8])then
begin
key:=#0;
messagebeep(1);
end;
end;

end.