Collaboration diagram for I/O:

Classes
class	std::basic_filebuf< _CharT, _Traits >
class	std::basic_fstream< _CharT, _Traits >
class	std::basic_ifstream< _CharT, _Traits >
class	std::basic_ios< _CharT, _Traits >
class	std::basic_iostream< _CharT, _Traits >
class	std::basic_istream< _CharT, _Traits >
class	std::basic_istringstream< _CharT, _Traits, _Alloc >
class	std::basic_ofstream< _CharT, _Traits >
class	std::basic_ostream< _CharT, _Traits >
class	std::basic_ostringstream< _CharT, _Traits, _Alloc >
class	std::basic_streambuf< _CharT, _Traits >
class	std::basic_stringbuf< _CharT, _Traits, _Alloc >
class	std::basic_stringstream< _CharT, _Traits, _Alloc >
class	std::ios_base
class	std::istreambuf_iterator< _CharT, _Traits >
class	std::ostreambuf_iterator< _CharT, _Traits >
class	__gnu_cxx::stdio_filebuf< _CharT, _Traits >
class	__gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >

Typedefs
typedef basic_filebuf< char >	std::filebuf
typedef basic_fstream< char >	std::fstream
typedef basic_ifstream< char >	std::ifstream
typedef basic_ios< char >	std::ios
typedef basic_iostream< char >	std::iostream
typedef basic_istream< char >	std::istream
typedef basic_istringstream< char >	std::istringstream
typedef basic_ofstream< char >	std::ofstream
typedef basic_ostream< char >	std::ostream
typedef basic_ostringstream< char >	std::ostringstream
typedef basic_streambuf< char >	std::streambuf
typedef basic_stringbuf< char >	std::stringbuf
typedef basic_stringstream< char >	std::stringstream
typedef basic_filebuf< wchar_t >	std::wfilebuf
typedef basic_fstream< wchar_t >	std::wfstream
typedef basic_ifstream< wchar_t >	std::wifstream
typedef basic_ios< wchar_t >	std::wios
typedef basic_iostream< wchar_t >	std::wiostream
typedef basic_istream< wchar_t >	std::wistream
typedef basic_istringstream< wchar_t >	std::wistringstream
typedef basic_ofstream< wchar_t >	std::wofstream
typedef basic_ostream< wchar_t >	std::wostream
typedef basic_ostringstream< wchar_t >	std::wostringstream
typedef basic_streambuf< wchar_t >	std::wstreambuf
typedef basic_stringbuf< wchar_t >	std::wstringbuf
typedef basic_stringstream< wchar_t >	std::wstringstream

Detailed Description

Nearly all of the I/O classes are parameterized on the type of characters they read and write. (The major exception is ios_base at the top of the hierarchy.) This is a change from pre-Standard streams, which were not templates.

For ease of use and compatibility, all of the basic_* I/O-related classes are given typedef names for both of the builtin character widths (wide and narrow). The typedefs are the same as the pre-Standard names, for example:

typedef basic_ifstream<char> ifstream;

std::ifstream

basic_ifstream< char > ifstream

Class for char input file streams.

Definition iosfwd_file.h:65

Because properly forward-declaring these classes can be difficult, you should not do it yourself. Instead, include the <iosfwd> header, which contains only declarations of all the I/O classes as well as the typedefs. Trying to forward-declare the typedefs themselves (e.g., class ostream;) is not valid ISO C++.

For more specific declarations, see https://gcc.gnu.org/onlinedocs/libstdc++/manual/io.html#std.io.objects