Defined in header <fstream> template<
class CharT,
class Traits = std::char_traits<CharT>
> class basic_filebuf : public std::basic_streambuf<CharT, Traits>
std::basic_filebuf is a std::basic_streambuf whose associated character sequence is a file. Both the input sequence and the output sequence are associated with the same file, and a joint file position is maintained for both operations.
The functions underflow() and overflow()/sync() perform t