TScreen 类 - 程序中窗体的个数

//一个包含两个窗体的例子, 这是工程中的内容:
program Project1;

uses
  Forms,
  Unit1 in 'Unit1.pas' {Form1},
  Unit2 in 'Unit2.pas' {Form2};

{$R *.res}

begin
  Application.Initialize;
  Application.MainFormOnTaskbar := True;
  Application.CreateForm(TForm1, Form1);
  Application.CreateForm(TForm2, Form2);
  Application.Run;
end.


//
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}

uses Unit2;

procedure TForm1.Button1Click(Sender: TObject);
var
  num: Integer;
begin
  num := Screen.FormCount;    {当前程序中窗体的个数}
  ShowMessage(IntToStr(num)); {2}

  Screen.Forms[1].ShowModal;  {显示第二个窗体}
  {上面这句相当于}
  //Form2.ShowModal;
end;

end.