std::fsetpos (3) - Linux Manuals
Defined in header <cstdio>
int fsetpos( std::FILE* stream, const std::fpos_t* pos );
Sets the file position indicator and the multibyte parsing state (if any) for the C file stream stream according to the value pointed to by pos.
Besides establishing new parse state and position, a call to this function undoes the effects of std::ungetc and clears the end-of-file state, if it is set.
If a read or write error occurs, the error indicator (std::ferror)for the stream is set.
stream - file stream to modify
pos - pointer to a fpos_t object obtained from std::fgetpos called on a stream associated with the same file
0 upon success, nonzero value otherwise. Also, sets errno on failure.
After seeking to a non-end position in a wide stream, the next call to any output function may render the remainder of the file undefined, e.g. by outputting a multibyte sequence of a different length.