Returns the name of the active worksheet
[C++]
static int GetActiveWorksheetName(
   CString& book_name,
   bool full_name = false
);
A reference to a string that will contain the desired data if the function succeeds.
If true, then the full sheet name will be returned, in the form "[BOOK1.XLS]Sheet1". If false, then only the sheet name will be returned.
Zero if the function has been called successfully; non-zero
            if the function could not be called.
            See Error codes for a list
            of return values.
Header: xlfuncs.h