Standard C++ Library Reference ISO/IEC (VERSION3)

basic_streambuf::sgetc
int_type sgetc();
If a read position is available, the member function returns
traits_type::to_int_type( *gptr()) Otherwise, it returns underflow().
basic_streambuf::sgetn
streamsize sgetn(char_type *ptr, streamsize count);
The member function returns xsgetn(ptr, count).
basic_streambuf::showmanyc
virtual streamsize showmanyc();
The protected virtual member function returns a count of the number of characters that can be
extracted from the input stream with no fear that the program will suffer an indefinite wait. The
default behavior is to return zero.
basic_streambuf::snextc
int_type snextc();
The member function calls sbumpc() and, if that function returns traits_type::eof(),
returns traits_type::eof(). Otherwise, it returns sgetc().
basic_streambuf::sputbackc
int_type sputbackc(char_type ch);
If a putback position is available and ch compares equal to the character stored in that position,
the member function decrements the next pointer for the input buffer and returns
traits_type::to_int_type(ch). Otherwise, it returns pbackfail(ch).
basic_streambuf::sputc
int_type sputc(char_type ch);
If a write position is available, the member function stores ch in the write position, increments
the next pointer for the output buffer, and returns traits_type::to_int_type(ch).
Otherwise, it returns overflow(ch).