Raymond Chen wrote a useful article on how to switch an application between windowed and full screen . The important part for you will be this section of code:
GetMonitorInfo(MonitorFromWindow(hwnd, MONITOR_DEFAULTTOPRIMARY), &mi))
This retrieves the monitor information for a particular monitor, but uses the value returned from MonitorFromWindowto select the monitor that the current window is on. There are several other ways to select a monitor, for example, providing an X, Y coordinate or listing them (using EnumDisplayMonitors(...)).
GetMonitorInfo(...)passes a MONITORINFOback, which contains the relative position and size of the display, which you can use to position the full-screen window.
The full API is described in detail on MSDN .