30 Input/output library [input.output]

30.10 File systems [filesystems]

30.10.8 Class path [fs.class.path] path members [fs.path.member] path decomposition [fs.path.decompose]

path root_name() const;

Returns: root-name, if the pathname in the generic format includes root-name, otherwise path().

path root_directory() const;

Returns: root-directory, if the pathname in the generic format includes root-directory, otherwise path().

path root_path() const;

Returns: root_­name() / root_­directory().

path relative_path() const;

Returns: A path composed from the pathname in the generic format, if empty() is false, beginning with the first filename after root-path. Otherwise, path().

path parent_path() const;

Returns: *this if has_­relative_­path() is false, otherwise a path whose generic format pathname is the longest prefix of the generic format pathname of *this that produces one fewer element in its iteration.

path filename() const;

Returns: relative_­path().empty() ? path() : *--end().


path("/foo/bar.txt").filename();   // yields "bar.txt"
path("/foo/bar").filename();       // yields "bar"
path("/foo/bar/").filename();      // yields ""
path("/").filename();              // yields ""
path("//host").filename();         // yields ""
path(".").filename();              // yields "."
path("..").filename();             // yields ".."

end example]

path stem() const;

Returns: Let f be the generic format pathname of filename(). Returns a path whose pathname in the generic format is

  • f, if it contains no periods other than a leading period or consists solely of one or two periods;

  • otherwise, the prefix of f ending before its last period.


std::cout << path("/foo/bar.txt").stem(); // outputs "bar"
path p = "foo.bar.baz.tar";
for (; !p.extension().empty(); p = p.stem())
  std::cout << p.extension() << '\n';
  // outputs: .tar
  //          .baz
  //          .bar

end example]

path extension() const;

Returns: a path whose pathname in the generic format is the suffix of filename() not included in stem().


path("/foo/bar.txt").extension();  // yields ".txt" and stem() is "bar"
path("/foo/bar").extension();      // yields "" and stem() is "bar"
path("/foo/.profile").extension(); // yields "" and stem() is ".profile"
path(".bar").extension();          // yields "" and stem() is ".bar"
path("..bar").extension();         // yields ".bar" and stem() is "."

end example]

[Note: The period is included in the return value so that it is possible to distinguish between no extension and an empty extension. end note]

[Note: On non-POSIX operating systems, for a path p, it may not be the case that p.stem() + p.extension() == p.filename(), even though the generic format pathnames are the same. end note]