入口函数WinMain

int WINAPI WinMain()
  HINSTANCE hInstance, 
  HINSTANCE hPrevInstance, 
  LPWSTR lpCmdLine, 
  int nShowCmd 
); 

Parameters

hInstance

[in] Handle to the current instance of the application.

hPrevInstance

[in] Handle to the previous instance of the application. For a Win32-based 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 GetLastError function will return ERROR_ALREADY_EXISTS. This indicates that another instance of your application exists, because it created the mutex first.

lpCmdLine

[in] Pointer to a null-terminated string that specifies the command line for the application, excluding the program name.

nShowCmd

[in] Specifies how the window is to be shown. This parameter can be one of the following values:

Value	Description
SW_HIDE	Hides the window and activates another window.
SW_SHOW	Activates a window and displays it in its current size and position.
SW_SHOWNA	Displays a window in its current state. The active window remains active.
SW_SHOWNOACTIVATE	Displays a window in its most recent size and position. The active window remains active.
SW_SHOWNORMAL	Activates and displays a window. If the window is minimized or maximized, the system restores it to its original size and position (same as SW_RESTORE).