WinMain - 如何检测是否已有应用程序的实例运行

不能用hInstance参数

以下摘自MSDN:

hPrevInstance

[in] Handle to the previous instance of the application. This parameter is always NULL. If you need to detect whether another instance already exists, create a uniquely named mutex using the CreateMutex function. CreateMutex will succeed even if the mutex already exists, but the function will return ERROR_ALREADY_EXISTS. This indicates that another instance of your application exists, because it created the mutex first.