Upon successful completion, the fgetwc function returns the wide- character code read from the file pointed to by file_ptr and converted to type wint_t. If the file is at end-of-file, the end-of-file indicator is set, and WEOF is returned. If an I/O read error occurred, then the error indicator is set, and WEOF is returned. Applications can use ferror or feof to distinguish between an error condition and an end-of-file condition.