实现一个人工选择累加器

Question

功能：用户在Listbox选择间隔秒数(比如2秒)然后按开始(button1)键，从0开始累加计数（隔2秒累加1），显示结果在edit，按停止键(button2),停止累加，要求写出代码。

Answer 1

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls;type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    Button1: TButton;
    Button2: TButton;
    Timer1: TTimer;
    Edit1: TEdit;
    procedure FormShow(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    vg_index:Integer;
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.FormShow(Sender: TObject);
begin
  vg_index:=0;
end;procedure TForm1.Button1Click(Sender: TObject);
begin
  self.Timer1.Interval:=2000;
  self.Timer1.Enabled:=True;
end;procedure TForm1.Button2Click(Sender: TObject);
begin
  self.Timer1.Enabled:=False;
end;procedure TForm1.Timer1Timer(Sender: TObject);
var
  i:Integer;
  s:string;
begin
  s:=self.ListBox1.Items.Strings[self.vg_index];
  self.Edit1.Text:=s;
  i:=self.ListBox1.Items.Count;
  if self.vg_index+1=i then
    self.vg_index:=0
  else
    self.vg_index:=self.vg_index+1;
end;end.

Answer 2

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls;type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    Button1: TButton;
    Button2: TButton;
    Timer1: TTimer;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
begin
  Edit1.Text:='0';
  Timer1.Interval:=strtoint(ListBox1.Items[ListBox1.ItemIndex])*1000;
  Timer1.Enabled:=True;
end;procedure TForm1.Button2Click(Sender: TObject);
begin
  Timer1.Enabled:=False;
end;procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Edit1.Text:=inttostr(strtoint(Edit1.Text)+1);
end;end.