This function copies the text of the specified window's title bar — if it has one — into a buffer. If the specified window is a control, the text of the control is copied. A remote application interface (RAPI) version of this function exists, and it is called CeGetWindowText (RAPI).
int GetWindowText( HWND hWnd, LPTSTR lpString, int nMaxCount );
The length, in characters, of the copied string, not including the terminating null character, indicates success. Zero indicates that the window has no title bar or text, if the title bar is empty, or if the window or control handle is invalid. To get extended error information, call GetLastError.
This function cannot retrieve the text of an edit control in another application.
When working with RAPI for Windows CE 1.0 and 1.01, use the PegGetWindowText function.
If the target window is owned by the current process, GetWindowText causes a WM_GETTEXT message to be sent to the specified window or control. If the target window is owned by another process and has a caption, GetWindowText retrieves the window caption text. If the window does not have a caption, the return value is a null string.