streamsize in_avail();
Returns: If a read position is available, returns egptr() - gptr(). Otherwise returns showmanyc().
int_type snextc();
Returns: If that function returns traits::eof(), returns traits::eof(). Otherwise, returns sgetc().
int_type sbumpc();
Returns: If the input sequence read position is not available, returns uflow(). Otherwise, returns traits::to_int_type(*gptr()) and increments the next pointer for the input sequence.
int_type sgetc();
Returns: If the input sequence read position is not available, returns underflow(). Otherwise, returns traits::to_int_type(*gptr()).
streamsize sgetn(char_type* s, streamsize n);