29 Input/output library [input.output]

29.10 File-based streams [file.streams]

29.10.1 Header <fstream> synopsis [fstream.syn]

namespace std { template<class charT, class traits = char_traits<charT>> class basic_filebuf; template<class charT, class traits> void swap(basic_filebuf<charT, traits>& x, basic_filebuf<charT, traits>& y); using filebuf = basic_filebuf<char>; using wfilebuf = basic_filebuf<wchar_t>; template<class charT, class traits = char_traits<charT>> class basic_ifstream; template<class charT, class traits> void swap(basic_ifstream<charT, traits>& x, basic_ifstream<charT, traits>& y); using ifstream = basic_ifstream<char>; using wifstream = basic_ifstream<wchar_t>; template<class charT, class traits = char_traits<charT>> class basic_ofstream; template<class charT, class traits> void swap(basic_ofstream<charT, traits>& x, basic_ofstream<charT, traits>& y); using ofstream = basic_ofstream<char>; using wofstream = basic_ofstream<wchar_t>; template<class charT, class traits = char_traits<charT>> class basic_fstream; template<class charT, class traits> void swap(basic_fstream<charT, traits>& x, basic_fstream<charT, traits>& y); using fstream = basic_fstream<char>; using wfstream = basic_fstream<wchar_t>; }
The header <fstream> defines four class templates and eight types that associate stream buffers with files and assist reading and writing files.
[Note 1:
The class template basic_­filebuf treats a file as a source or sink of bytes.
In an environment that uses a large character set, the file typically holds multibyte character sequences and the basic_­filebuf object converts those multibyte sequences into wide character sequences.
— end note]
In subclause [file.streams], member functions taking arguments of const filesystem​::​path​::​value_­type* are only provided on systems where filesystem​::​path​::​value_­type ([fs.class.path]) is not char.
[Note 2:
These functions enable class path support for systems with a wide native path character type, such as wchar_­t.
— end note]