单例程序

#define P4301_UI_EXE_ID   _T("P4301_UI_EXE_ID")

 

BOOL CALLBACK EnumWndProc(HWND hwnd,LPARAM lParam)
{
 HANDLE hPreWnd = GetProp(hwnd,P4301_UI_EXE_ID);
 if( hPreWnd == (HANDLE)1)
 {
  *(HWND*)lParam = hwnd;
  return false;
 }

 return true;
}

 

BOOL App::InitInstance()
{

 // Standard initialization
 // If you are not using these features and wish to reduce the size
 // of your final executable, you should remove from the following
 // the specific initialization routines you do not need
 // Change the registry key under which our settings are stored
 // TODO: You should modify this string to be something appropriate
 // such as the name of your company or organization
 HWND oldHWnd = NULL;
 EnumWindows(EnumWndProc,(LPARAM)&oldHWnd); //枚举所有运行的窗口
 if(oldHWnd != NULL)
 {
  showTaskBar(SW_HIDE);
  ::ShowWindow(oldHWnd,SW_SHOW);   //激活找到的前一个程序
  ::SetForegroundWindow(oldHWnd);   //把它设为前景窗口
  PostQuitMessage(0);
  return false;       //退出本次运行
 }

// CMainDlg message handlers
BOOL CMainDlg::OnInitDialog()
{
 CDialog::OnInitDialog();
 SetProp(m_hWnd,P4301_UI_EXE_ID,(HANDLE)1);

...

}

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