The header 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.