The ferror() function returns a non-zero valuewhen an error has previously occurred reading from or writing to the named stream (see intro(3)). It returns 0 otherwise.

The feof() function returns a non-zero value when EOF has previously been detected reading the named input stream. It returns 0 otherwise.

The clearerr() function resets the error indicator and EOF indicator to 0 on the named stream.

The fileno() function returns the integer file descriptor associated with the named stream; see open(2).

See attributes(5) for descriptions of the following attributes:

open(2), intro(3), fopen(3C), stdio(3C), attributes(5)