p00404.dpr

Delphi编程五大妙招源程序

program P00404;

uses
  windows,
  Forms,
  U00404 in 'U00404.pas' {frmSingle};

{$R *.RES}
const
      ClassName='TfrmSingle'; {声明为主窗体的类名}
var
      Handle:integer; {变量}

begin
  handle:=findwindow(classname,nil);  //查找是否有此类的窗体
  if handle<>0 then   //不为0则程序已运行
  begin
    messagebox(0,'该程序已经有一个在运行中！','运行',0);//提示程序已运行
    halt; //退出程序
  end;

  Application.Initialize;
  Application.CreateForm(TfrmSingle, frmSingle);
  Application.Run;
end.