int ReleaseDC( CDC* pDC );
pDC
Identifies the device context to be released.
Releases a device context, freeing it for use by other applications. The effect of the ReleaseDC member function depends on the device-context type. It only frees common and window device contexts. It has no effect on class or private device contexts.
The application must call the ReleaseDC member function for each call to the GetWindowDC member function and for each call to the GetDC member function that retrieves a common device context.
Specifies whether the device context is released. It is 1 if the device context is released; otherwise 0.
CWnd::GetDC, CWnd::GetWindowDC, ::ReleaseDC