Returns a C character string which is the name of the file (including full path) that net was last written to or read from.

If net was not read from a file, and has not yet been written to a file, the empty string (rather than NULL) is returned.

If you need the string to persist, make a copy of the string returned, since its contents may become invalid after further calls to Netica API. Do not try to directly modify or free the list returned.