XPferror()
  Return error code of one of the binary file functions
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   Function:   XPferror()

               This function ould be called after any of the functions
               in the "See Also" list have been called. It returns the DOS
               Error code for the last call, or 0 when there was no error.
               It works much like Clipper's XPferror(), except that we need
               another for our own functions.

   Syntax:     XPferror() --> nDosErrCode

   Arguments:  None.

   Returns:    The DOS Error code for the last call. Possible error
               codes are one of the following:

                    0       No Error
                    2       File not found
                    3       Path not found (subtle difference with 2)
                    4       No more handles available
                    5       Access denied (read-only file, networks..)
                    6       Invalid handle
                   15       Invalid drive
                   32       File sharing violation
                   33       File locking violation (region already locked)
                   80       File exists (XPfcreateNew())

               See the XPdosMsg() function in the Library for more
               more information on Error codes.

   Usage:      h := fcreateNew('A_FILE')
               if XPferror() = 80
                    ? "File already exists!"
               end