学习官方示例 - System.RunError

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    procedure Button1Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



var P: Pointer;



procedure TForm1.Button1Click(Sender: TObject);

begin

  if P = nil then

    RunError(204);

end;



end.