这个程序的操作为：在form1窗体中分别添加listbox，memo，edit，button，然后双击button空间在弹出的代码编辑器中输入程序，最终在memo控件中显示用户在listbox中选定的项目。但是总是有错误，请高手指点一下。

unit Unit1;

interface

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

type
TForm1 = class(TForm)
Edit1: TEdit;
ListBox1: TListBox;
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
Memo1.Lines.Add(Edit1.Text);
If ListBox1.ItemIndex>=0
Then Memo1.Lines.Add(ListBox1.Items[ListBox1.ItemIndex])

end;

end.