cpp/io/c/fsetpos

Sets the file position indicator and the multibyte parsing state (if any) for the C file stream according to the value pointed to by.

Besides establishing new parse state and position, a call to this function undoes the effects of std and clears the end-of-file state, if it is set.

If a read or write error occurs, the error indicator (std) for the stream is set.

Return value
upon success, nonzero value otherwise. Also, sets errno on failure.