cppdraft_translate/cppdraft/fs/class/path.md

[fs.class.path]

# 31 Input/output library [[input.output]](./#input.output)

## 31.12 File systems [[filesystems]](filesystems#fs.class.path)

### 31.12.6 Class path [fs.class.path]

#### [31.12.6.1](#general) General [[fs.class.path.general]](fs.class.path.general)

[1](#general-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13559)

An object of class path represents a path
and contains a pathname[.](#general-1.sentence-1)

Such an object is concerned only with the lexical and syntactic aspects
of a path[.](#general-1.sentence-2)

The path does not necessarily exist in external storage, and the
pathname is not necessarily valid for the current operating
system or for a particular file system[.](#general-1.sentence-3)

[2](#general-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13567)

[*Note [1](#general-note-1)*:

Class path is used to support the differences
between the string types used by different operating systems
to represent pathnames,
and to perform conversions between encodings when necessary[.](#general-2.sentence-1)

— *end note*]

[3](#general-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13575)

A [*path*](#def:path "31.12.6.1 General [fs.class.path.general]") is
a sequence of elements that identify
the location of a file within a filesystem[.](#general-3.sentence-1)

The elements are the[*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]")opt,[*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]")opt,
and an optional sequence of [*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]")*s* ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format"))[.](#general-3.sentence-2)

The maximum number of elements in the sequence is
operating system dependent ([[fs.conform.os]](fs.conform.os "31.12.2.3 Operating system dependent behavior conformance"))[.](#general-3.sentence-3)

[4](#general-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13586)

An [*absolute path*](#def:path,absolute "31.12.6.1 General [fs.class.path.general]") is a path that unambiguously
identifies the location of a file without reference to an additional starting
location[.](#general-4.sentence-1)

The elements of a path that determine if it is absolute are
operating system dependent[.](#general-4.sentence-2)

A [*relative path*](#def:path,relative "31.12.6.1 General [fs.class.path.general]") is
a path that is not absolute, and as such, only unambiguously
identifies the location of a file when resolved relative to
an implied starting location[.](#general-4.sentence-3)

The elements of a path that determine if it is
relative are operating system dependent[.](#general-4.sentence-4)

[*Note [2](#general-note-2)*:

Pathnames “.” and “..” are relative paths[.](#general-4.sentence-5)

— *end note*]

[5](#general-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13600)

A [*pathname*](#def:pathname "31.12.6.1 General [fs.class.path.general]") is
a character string that represents the name of a path[.](#general-5.sentence-1)

Pathnames are
formatted according to the generic pathname format grammar ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format"))
or according to an
operating system dependent[*native pathname format*](#def:native_pathname_format "31.12.6.1 General [fs.class.path.general]") accepted by the host operating system[.](#general-5.sentence-2)

[6](#general-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13608)

[*Pathname resolution*](#def:pathname_resolution "31.12.6.1 General [fs.class.path.general]") is the operating system dependent mechanism for resolving
a pathname to a particular file in a file hierarchy[.](#general-6.sentence-1)

There may be multiple
pathnames that resolve to the same file[.](#general-6.sentence-2)

[*Example [1](#general-example-1)*:

For POSIX-based operating systems,
this mechanism is specified in POSIX, section 4.12, Pathname resolution[.](#general-6.sentence-3)

— *end example*]

namespace std::filesystem {class path {public:using value_type = *see below*; using string_type = basic_string<value_type>; static constexpr value_type preferred_separator = *see below*; // [[fs.enum.path.format]](fs.enum.path.format "31.12.8.1 Enum path​::​format"), enumeration formatenum format; // [[fs.path.construct]](#fs.path.construct "31.12.6.5.1 Constructors"), constructors and destructor path() noexcept;
 path(const path& p);
 path(path&& p) noexcept;
 path(string_type&& source, format fmt = auto_format); template<class Source> path(const Source& source, format fmt = auto_format); template<class InputIterator> path(InputIterator first, InputIterator last, format fmt = auto_format); template<class Source> path(const Source& source, const locale& loc, format fmt = auto_format); template<class InputIterator> path(InputIterator first, InputIterator last, const locale& loc, format fmt = auto_format); ~path(); // [[fs.path.assign]](#fs.path.assign "31.12.6.5.2 Assignments"), assignments path& operator=(const path& p);
 path& operator=(path&& p) noexcept;
 path& operator=(string_type&& source);
 path& assign(string_type&& source); template<class Source> path& operator=(const Source& source); template<class Source> path& assign(const Source& source); template<class InputIterator> path& assign(InputIterator first, InputIterator last); // [[fs.path.append]](#fs.path.append "31.12.6.5.3 Appends"), appends path& operator/=(const path& p); template<class Source> path& operator/=(const Source& source); template<class Source> path& append(const Source& source); template<class InputIterator> path& append(InputIterator first, InputIterator last); // [[fs.path.concat]](#fs.path.concat "31.12.6.5.4 Concatenation"), concatenation path& operator+=(const path& x);
 path& operator+=(const string_type& x);
 path& operator+=(basic_string_view<value_type> x);
 path& operator+=(const value_type* x);
 path& operator+=(value_type x); template<class Source> path& operator+=(const Source& x); template<class EcharT> path& operator+=(EcharT x); template<class Source> path& concat(const Source& x); template<class InputIterator> path& concat(InputIterator first, InputIterator last); // [[fs.path.modifiers]](#fs.path.modifiers "31.12.6.5.5 Modifiers"), modifiersvoid clear() noexcept;
 path& make_preferred();
 path& remove_filename();
 path& replace_filename(const path& replacement);
 path& replace_extension(const path& replacement = path()); void swap(path& rhs) noexcept; // [[fs.path.nonmember]](#fs.path.nonmember "31.12.6.8 Non-member functions"), non-member operatorsfriend bool operator==(const path& lhs, const path& rhs) noexcept; friend strong_ordering operator<=>(const path& lhs, const path& rhs) noexcept; friend path operator/(const path& lhs, const path& rhs); // [[fs.path.native.obs]](#fs.path.native.obs "31.12.6.5.6 Native format observers"), native format observersconst string_type& native() const noexcept; const value_type* c_str() const noexcept; operator string_type() const; template<class EcharT, class traits = char_traits<EcharT>, class Allocator = allocator<EcharT>> basic_string<EcharT, traits, Allocator> string(const Allocator& a = Allocator()) const;
 std::string display_string() const;
 std::string system_encoded_string() const;
 std::wstring wstring() const;
 std::u8string u8string() const;
 std::u16string u16string() const;
 std::u32string u32string() const; // [[fs.path.generic.obs]](#fs.path.generic.obs "31.12.6.5.7 Generic format observers"), generic format observerstemplate<class EcharT, class traits = char_traits<EcharT>, class Allocator = allocator<EcharT>> basic_string<EcharT, traits, Allocator> generic_string(const Allocator& a = Allocator()) const;
 std::string generic_display_string() const;
 std::string generic_system_encoded_string() const;
 std::wstring generic_wstring() const;
 std::u8string generic_u8string() const;
 std::u16string generic_u16string() const;
 std::u32string generic_u32string() const; // [[fs.path.compare]](#fs.path.compare "31.12.6.5.8 Compare"), compareint compare(const path& p) const noexcept; int compare(const string_type& s) const; int compare(basic_string_view<value_type> s) const; int compare(const value_type* s) const; // [[fs.path.decompose]](#fs.path.decompose "31.12.6.5.9 Decomposition"), decomposition path root_name() const;
 path root_directory() const;
 path root_path() const;
 path relative_path() const;
 path parent_path() const;
 path filename() const;
 path stem() const;
 path extension() const; // [[fs.path.query]](#fs.path.query "31.12.6.5.10 Query"), querybool empty() const noexcept; bool has_root_name() const; bool has_root_directory() const; bool has_root_path() const; bool has_relative_path() const; bool has_parent_path() const; bool has_filename() const; bool has_stem() const; bool has_extension() const; bool is_absolute() const; bool is_relative() const; // [[fs.path.gen]](#fs.path.gen "31.12.6.5.11 Generation"), generation path lexically_normal() const;
 path lexically_relative(const path& base) const;
 path lexically_proximate(const path& base) const; // [[fs.path.itr]](#fs.path.itr "31.12.6.6 Iterators"), iteratorsclass iterator; using const_iterator = iterator;

 iterator begin() const;
 iterator end() const; // [[fs.path.io]](#fs.path.io "31.12.6.7 Inserter and extractor"), path inserter and extractortemplate<class charT, class traits>friend basic_ostream<charT, traits>&operator<<(basic_ostream<charT, traits>& os, const path& p); template<class charT, class traits>friend basic_istream<charT, traits>&operator>>(basic_istream<charT, traits>& is, path& p); };}

[7](#general-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13775)

value_type is a typedef for the
operating system dependent encoded character type used to represent pathnames[.](#general-7.sentence-1)

[8](#general-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13780)

The value of the preferred_separator member
is the operating system dependent [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]") character ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format"))[.](#general-8.sentence-1)

[9](#general-9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13784)

[*Example [2](#general-example-2)*:

For POSIX-based operating systems,value_type is char andpreferred_separator is the slash character ('/')[.](#general-9.sentence-1)

For Windows-based operating systems,value_type is wchar_t andpreferred_separator is the backslash character (L'\\')[.](#general-9.sentence-2)

— *end example*]

#### [31.12.6.2](#fs.path.generic) Generic pathname format [[fs.path.generic]](fs.path.generic)

[pathname:](#nt:pathname "31.12.6.2 Generic pathname format [fs.path.generic]")  
[*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]")opt [*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]")opt [*relative-path*](#nt:relative-path "31.12.6.2 Generic pathname format [fs.path.generic]")

[root-name:](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]")  
operating system dependent sequences of characters  
implementation-defined sequences of characters

[root-directory:](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]")  
[*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")

[relative-path:](#nt:relative-path "31.12.6.2 Generic pathname format [fs.path.generic]")  
[*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]")  
[*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") [*relative-path*](#nt:relative-path "31.12.6.2 Generic pathname format [fs.path.generic]")  
an empty path

[filename:](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]")  
non-empty sequence of characters other than [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") characters

[directory-separator:](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")  
[*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]") [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")opt  
[*fallback-separator*](#nt:fallback-separator "31.12.6.2 Generic pathname format [fs.path.generic]") [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")opt

[preferred-separator:](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]")  
operating system dependent directory separator character

[fallback-separator:](#nt:fallback-separator "31.12.6.2 Generic pathname format [fs.path.generic]")  
/, if [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]") is not /

[1](#fs.path.generic-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13843)

A [*filename*](#def:filename "31.12.6.2 Generic pathname format [fs.path.generic]") is
the name of a file[.](#fs.path.generic-1.sentence-1)

The [*dot*](#def:dot,filename "31.12.6.2 Generic pathname format [fs.path.generic]") and [*dot-dot*](#def:dot-dot,filename "31.12.6.2 Generic pathname format [fs.path.generic]") filenames,
consisting solely of one and two period characters respectively,
have special meaning[.](#fs.path.generic-1.sentence-2)

The following characteristics of filenames are operating system dependent:

- [(1.1)](#fs.path.generic-1.1)

  The permitted characters[.](#fs.path.generic-1.1.sentence-1)
  [*Example [1](#fs.path.generic-example-1)*:
  Some operating systems prohibit
 the ASCII control characters (0x00 – 0x1F) in filenames[.](#fs.path.generic-1.1.sentence-2)
 — *end example*]
  [*Note [1](#fs.path.generic-note-1)*:
  Wider portability can be achieved by limiting [*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") characters to the POSIX Portable Filename Character Set:   
  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z   
  a b c d e f g h i j k l m n o p q r s t u v w x y z   
  0 1 2 3 4 5 6 7 8 9 . _ -
 — *end note*]

- [(1.2)](#fs.path.generic-1.2)

  The maximum permitted length[.](#fs.path.generic-1.2.sentence-1)

- [(1.3)](#fs.path.generic-1.3)

  Filenames that are not permitted[.](#fs.path.generic-1.3.sentence-1)

- [(1.4)](#fs.path.generic-1.4)

  Filenames that have special meaning[.](#fs.path.generic-1.4.sentence-1)

- [(1.5)](#fs.path.generic-1.5)

  Case awareness and sensitivity during path resolution[.](#fs.path.generic-1.5.sentence-1)

- [(1.6)](#fs.path.generic-1.6)

  Special rules that may apply to file types other than regular
 files, such as directories[.](#fs.path.generic-1.6.sentence-1)

[2](#fs.path.generic-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13870)

Except in a [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]"),
multiple successive [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") characters are considered to
be the same as one [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") character[.](#fs.path.generic-2.sentence-1)

[3](#fs.path.generic-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13875)

The dot filename is treated as a reference to the current directory[.](#fs.path.generic-3.sentence-1)

The dot-dot filename is treated as a reference to the parent directory[.](#fs.path.generic-3.sentence-2)

What the dot-dot filename refers to
relative to [*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]") is implementation-defined[.](#fs.path.generic-3.sentence-3)

Specific filenames may have special meanings for a particular operating system[.](#fs.path.generic-3.sentence-4)

[4](#fs.path.generic-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13882)

A [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") identifies the
starting location for pathname resolution ([fs.class.path])[.](#fs.path.generic-4.sentence-1)

If there are no operating system dependent [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]")*s*,
at least one implementation-defined [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") is required[.](#fs.path.generic-4.sentence-2)

[*Note [2](#fs.path.generic-note-2)*:

Many operating systems define a name
beginning with two [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") characters
as a [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") that identifies
network or other resource locations[.](#fs.path.generic-4.sentence-3)

Some operating systems
define a single letter followed by a colon
as a drive specifier — a [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") identifying a specific device such as a disk drive[.](#fs.path.generic-4.sentence-4)

— *end note*]

[5](#fs.path.generic-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13898)

If a [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") is otherwise ambiguous,
the possibility with the longest sequence of characters is chosen[.](#fs.path.generic-5.sentence-1)

[*Note [3](#fs.path.generic-note-3)*:

On a POSIX-like operating system, it is impossible to have a[*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") and a [*relative-path*](#nt:relative-path "31.12.6.2 Generic pathname format [fs.path.generic]") without an intervening [*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]") element[.](#fs.path.generic-5.sentence-2)

— *end note*]

[6](#fs.path.generic-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13907)

[*Normalization*](#def:normalization,path "31.12.6.2 Generic pathname format [fs.path.generic]") of a generic format pathname means:

| [1.](#fs.path.generic-6.1) | If the path is empty, stop[.](#fs.path.generic-6.1.sentence-1) |
| --- | --- |
| [2.](#fs.path.generic-6.2) | Replace each slash character in the [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") with a [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.generic-6.2.sentence-1) |
| [3.](#fs.path.generic-6.3) | Replace each [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") with a [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.generic-6.3.sentence-1)<br>[*Note [4](#fs.path.generic-note-4)*:<br>The generic pathname grammar defines [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") as one or more slashes and [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]")*s*[.](#fs.path.generic-6.3.sentence-2) — *end note*] |
| [4.](#fs.path.generic-6.4) | Remove each dot filename and any immediately following [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.generic-6.4.sentence-1) |
| [5.](#fs.path.generic-6.5) | As long as any appear, remove a non-dot-dot filename immediately followed by a [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") and a dot-dot filename, along with any immediately following [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.generic-6.5.sentence-1) |
| [6.](#fs.path.generic-6.6) | If there is a [*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]"), remove all dot-dot filenames and any [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")*s* immediately following them[.](#fs.path.generic-6.6.sentence-1)<br>[*Note [5](#fs.path.generic-note-5)*:<br>These dot-dot filenames attempt to refer to nonexistent parent directories[.](#fs.path.generic-6.6.sentence-2) — *end note*] |
| [7.](#fs.path.generic-6.7) | If the last filename is dot-dot, remove any trailing [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.generic-6.7.sentence-1) |
| [8.](#fs.path.generic-6.8) | If the path is empty, add a dot[.](#fs.path.generic-6.8.sentence-1) |

The result of normalization is a path in [*normal form*](#def:normal_form,path "31.12.6.2 Generic pathname format [fs.path.generic]"),
which is said to be [*normalized*](#def:normalized)[.](#fs.path.generic-6.sentence-2)

#### [31.12.6.3](#fs.path.cvt) Conversions [[fs.path.cvt]](fs.path.cvt)

#### [31.12.6.3.1](#fs.path.fmt.cvt) Argument format conversions [[fs.path.fmt.cvt]](fs.path.fmt.cvt)

[1](#fs.path.fmt.cvt-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13935)

[*Note [1](#fs.path.fmt.cvt-note-1)*:

The format conversions described in this subclause
are not applied on POSIX-based operating systems
because on these systems:

- [(1.1)](#fs.path.fmt.cvt-1.1)

  The generic format is acceptable as a native path[.](#fs.path.fmt.cvt-1.1.sentence-1)

- [(1.2)](#fs.path.fmt.cvt-1.2)

  There is no need to distinguish between native format and generic format in function arguments[.](#fs.path.fmt.cvt-1.2.sentence-1)

- [(1.3)](#fs.path.fmt.cvt-1.3)

  Paths for regular files and paths for directories share the same syntax[.](#fs.path.fmt.cvt-1.3.sentence-1)

— *end note*]

[2](#fs.path.fmt.cvt-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13947)

Several functions are defined to accept [*detected-format*](#def:detected-format) arguments,
which are character sequences[.](#fs.path.fmt.cvt-2.sentence-1)

A detected-format argument represents a path
using either a pathname in the generic format ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format"))
or a pathname in the native format ([fs.class.path])[.](#fs.path.fmt.cvt-2.sentence-2)

Such an argument is taken to be in the generic format if and only if
it matches the generic format and is not acceptable to the operating system
as a native path[.](#fs.path.fmt.cvt-2.sentence-3)

[3](#fs.path.fmt.cvt-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13956)

[*Note [2](#fs.path.fmt.cvt-note-2)*:

Some operating systems have no unambiguous way to distinguish between native format and generic format arguments[.](#fs.path.fmt.cvt-3.sentence-1)

This is by design as it simplifies use for operating systems that do not require
disambiguation[.](#fs.path.fmt.cvt-3.sentence-2)

It is possible that an implementation for an operating system
where disambiguation is needed distinguishes between the formats[.](#fs.path.fmt.cvt-3.sentence-3)

— *end note*]

[4](#fs.path.fmt.cvt-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13964)

Pathnames are converted as needed between the generic and native formats
in an operating-system-dependent manner[.](#fs.path.fmt.cvt-4.sentence-1)

Let *G(n)* and *N(g)* in a mathematical sense
be the implementation's functions that convert native-to-generic
and generic-to-native formats respectively[.](#fs.path.fmt.cvt-4.sentence-2)

If *g=G(n)* for some *n*, then *G(N(g))=g*;
if *n=N(g)* for some *g*, then *N(G(n))=n*[.](#fs.path.fmt.cvt-4.sentence-3)

[*Note [3](#fs.path.fmt.cvt-note-3)*:

Neither *G* nor *N* need be invertible[.](#fs.path.fmt.cvt-4.sentence-4)

— *end note*]

[5](#fs.path.fmt.cvt-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13976)

If the native format requires paths for regular files to be formatted
differently from paths for directories, the path shall be treated as a directory
path if its last element is a [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]"),
otherwise it shall be treated as a path to a regular file[.](#fs.path.fmt.cvt-5.sentence-1)

[6](#fs.path.fmt.cvt-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13982)

[*Note [4](#fs.path.fmt.cvt-note-4)*:

A path stores a native format pathname ([[fs.path.native.obs]](#fs.path.native.obs "31.12.6.5.6 Native format observers"))
and acts as if it also stores a generic format pathname,
related as given below[.](#fs.path.fmt.cvt-6.sentence-1)

The implementation can generate the generic format pathname
based on the native format pathname (and possibly other information)
when requested[.](#fs.path.fmt.cvt-6.sentence-2)

— *end note*]

[7](#fs.path.fmt.cvt-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13992)

When a path is constructed from or is assigned a single representation
separate from any path, the other representation is selected
by the appropriate conversion function (*G* or *N*)[.](#fs.path.fmt.cvt-7.sentence-1)

[8](#fs.path.fmt.cvt-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L13997)

When the (new) value *p* of one representation of a path
is derived from the representation of that or another path,
a value *q* is chosen for the other representation[.](#fs.path.fmt.cvt-8.sentence-1)

The value *q* converts to *p* (by *G* or *N* as appropriate)
if any such value does so;*q* is otherwise unspecified[.](#fs.path.fmt.cvt-8.sentence-2)

[*Note [5](#fs.path.fmt.cvt-note-5)*:

If *q* is the result of converting any path at all,
it is the result of converting *p*[.](#fs.path.fmt.cvt-8.sentence-3)

— *end note*]

#### [31.12.6.3.2](#fs.path.type.cvt) Type and encoding conversions [[fs.path.type.cvt]](fs.path.type.cvt)

[1](#fs.path.type.cvt-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14013)

The [*native encoding*](#def:native_encoding "31.12.6.3.2 Type and encoding conversions [fs.path.type.cvt]") of an ordinary character string is
the operating system dependent current encoding
for pathnames ([fs.class.path])[.](#fs.path.type.cvt-1.sentence-1)

The [*native encoding*](#def:native_encoding "31.12.6.3.2 Type and encoding conversions [fs.path.type.cvt]") for wide character strings is
the implementation-defined execution
wide-character set encoding ([[character.seq]](character.seq "16.3.3.3.4 Character sequences"))[.](#fs.path.type.cvt-1.sentence-2)

[2](#fs.path.type.cvt-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14021)

For member function arguments that take character sequences representing
paths and for member functions returning strings, value type and encoding
conversion is performed if the value type of the argument or return value differs frompath​::​value_type[.](#fs.path.type.cvt-2.sentence-1)

For the argument or return value, the method of conversion and the encoding
to be converted to is determined
by its value type:

- [(2.1)](#fs.path.type.cvt-2.1)

  char: The encoding is the native ordinary encoding[.](#fs.path.type.cvt-2.1.sentence-1)
  The method of conversion, if any, is operating system dependent[.](#fs.path.type.cvt-2.1.sentence-2)
  [*Note [1](#fs.path.type.cvt-note-1)*:
  For POSIX-based operating systems path​::​value_type is char so no conversion from char value type arguments or to char value type return values is performed[.](#fs.path.type.cvt-2.1.sentence-3)
  For Windows-based operating systems, the
native ordinary encoding is determined by calling a Windows API function[.](#fs.path.type.cvt-2.1.sentence-4)
 — *end note*]
  [*Note [2](#fs.path.type.cvt-note-2)*:
  This results in behavior identical to other C and C++
standard library functions that perform file operations using ordinary character
strings to identify paths[.](#fs.path.type.cvt-2.1.sentence-5)
  Changing this behavior would be surprising and
error-prone[.](#fs.path.type.cvt-2.1.sentence-6)
 — *end note*]

- [(2.2)](#fs.path.type.cvt-2.2)

  wchar_t: The encoding is the native wide encoding[.](#fs.path.type.cvt-2.2.sentence-1)
  The method of conversion is unspecified[.](#fs.path.type.cvt-2.2.sentence-2)
  [*Note [3](#fs.path.type.cvt-note-3)*:
  For Windows-based operating systems path​::​value_type is wchar_t so no conversion from wchar_t value type arguments or to wchar_t value type return values is performed[.](#fs.path.type.cvt-2.2.sentence-3)
 — *end note*]

- [(2.3)](#fs.path.type.cvt-2.3)

  char8_t: The encoding is UTF-8[.](#fs.path.type.cvt-2.3.sentence-1)
  The method of conversion
is unspecified[.](#fs.path.type.cvt-2.3.sentence-2)

- [(2.4)](#fs.path.type.cvt-2.4)

  char16_t: The encoding is UTF-16[.](#fs.path.type.cvt-2.4.sentence-1)
  The method of conversion
is unspecified[.](#fs.path.type.cvt-2.4.sentence-2)

- [(2.5)](#fs.path.type.cvt-2.5)

  char32_t: The encoding is UTF-32[.](#fs.path.type.cvt-2.5.sentence-1)
  The method of conversion
is unspecified[.](#fs.path.type.cvt-2.5.sentence-2)

[3](#fs.path.type.cvt-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14066)

If the encoding being converted to has no representation for source
characters, the resulting converted characters, if any, are unspecified[.](#fs.path.type.cvt-3.sentence-1)

Implementations should not modify member function arguments
if already of type path​::​value_type[.](#fs.path.type.cvt-3.sentence-2)

#### [31.12.6.4](#fs.path.req) Requirements [[fs.path.req]](fs.path.req)

[1](#fs.path.req-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14074)

In addition to the requirements ([[fs.req]](fs.req "31.12.3 Requirements")),
function template parameters named Source shall be one of:

- [(1.1)](#fs.path.req-1.1)

  basic_string<EcharT, traits, Allocator>[.](#fs.path.req-1.1.sentence-1)
  A function
 argument const Source& source shall have an
 effective range [source.begin(), source.end())[.](#fs.path.req-1.1.sentence-2)

- [(1.2)](#fs.path.req-1.2)

  basic_string_view<EcharT, traits>[.](#fs.path.req-1.2.sentence-1)
  A function
 argument const Source& source shall have an
 effective range [source.begin(), source.end())[.](#fs.path.req-1.2.sentence-2)

- [(1.3)](#fs.path.req-1.3)

  A type meeting the [*Cpp17InputIterator*](input.iterators#:Cpp17InputIterator "24.3.5.3 Input iterators [input.iterators]") requirements that iterates over an NTCTS[.](#fs.path.req-1.3.sentence-1)
  The value type shall be an encoded character type[.](#fs.path.req-1.3.sentence-2)
  A function argument const Source& source shall have an effective range
 [source, end) where end is the first
 iterator value with an element value equal to iterator_traits<Source>​::​value_type()[.](#fs.path.req-1.3.sentence-3)

- [(1.4)](#fs.path.req-1.4)

  A character array that after array-to-pointer decay results in a
 pointer to the start of an NTCTS[.](#fs.path.req-1.4.sentence-1)
  The value type shall be an encoded character type[.](#fs.path.req-1.4.sentence-2)
  A
 function argument const Source& source shall
 have an effective range [source, end) where end is the first iterator value with an element value equal to iterator_traits<decay_t<Source>>​::​value_type()[.](#fs.path.req-1.4.sentence-3)

[2](#fs.path.req-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14099)

Functions taking template parameters named Source shall not participate in overload resolution unlessSource denotes a type other than path, and
either

- [(2.1)](#fs.path.req-2.1)

Source is a specialization ofbasic_string or basic_string_view, or

- [(2.2)](#fs.path.req-2.2)

the [*qualified-id*](expr.prim.id.qual#nt:qualified-id "7.5.5.3 Qualified names [expr.prim.id.qual]") iterator_traits<decay_t<Source>>​::​value_type is valid and
denotes a possibly const encoded character type ([[temp.deduct]](temp.deduct "13.10.3 Template argument deduction"))[.](#fs.path.req-2.sentence-1)

[3](#fs.path.req-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14113)

[*Note [1](#fs.path.req-note-1)*:

See [path conversions](#fs.path.cvt "31.12.6.3 Conversions [fs.path.cvt]") for how the value types above and their encodings convert topath​::​value_type and its encoding[.](#fs.path.req-3.sentence-1)

— *end note*]

[4](#fs.path.req-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14120)

Arguments of type Source shall not be null pointers[.](#fs.path.req-4.sentence-1)

#### [31.12.6.5](#fs.path.member) Members [[fs.path.member]](fs.path.member)

#### [31.12.6.5.1](#fs.path.construct) Constructors [[fs.path.construct]](fs.path.construct)

[🔗](#lib:path,constructor)

`path() noexcept;
`

[1](#fs.path.construct-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14134)

*Postconditions*: empty() is true[.](#fs.path.construct-1.sentence-1)

[🔗](#lib:path,constructor_)

`path(const path& p);
path(path&& p) noexcept;
`

[2](#fs.path.construct-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14146)

*Effects*: Constructs an object of class path having the same pathname in the native and generic formats, respectively,
as the original value of p[.](#fs.path.construct-2.sentence-1)

In the second form, p is left in a valid but unspecified state[.](#fs.path.construct-2.sentence-2)

[🔗](#lib:path,constructor__)

`path(string_type&& source, format fmt = auto_format);
`

[3](#fs.path.construct-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14160)

*Effects*: Constructs an object of class path for which the pathname in the detected-format of source has the original value of source ([[fs.path.fmt.cvt]](#fs.path.fmt.cvt "31.12.6.3.1 Argument format conversions")),
converting format if required ([[fs.path.fmt.cvt]](#fs.path.fmt.cvt "31.12.6.3.1 Argument format conversions"))[.](#fs.path.construct-3.sentence-1)

source is left in a valid but unspecified state[.](#fs.path.construct-3.sentence-2)

[🔗](#lib:path,constructor___)

`template<class Source>
  path(const Source& source, format fmt = auto_format);
template<class InputIterator>
  path(InputIterator first, InputIterator last, format fmt = auto_format);
`

[4](#fs.path.construct-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14178)

*Effects*: Let s be the effective range of source ([[fs.path.req]](#fs.path.req "31.12.6.4 Requirements"))
or the range [first, last), with the encoding converted if required ([[fs.path.cvt]](#fs.path.cvt "31.12.6.3 Conversions"))[.](#fs.path.construct-4.sentence-1)

Finds the detected-format of s ([[fs.path.fmt.cvt]](#fs.path.fmt.cvt "31.12.6.3.1 Argument format conversions"))
and constructs an object of class path for which the pathname in that format is s[.](#fs.path.construct-4.sentence-2)

[🔗](#lib:path,constructor____)

`template<class Source>
  path(const Source& source, const locale& loc, format fmt = auto_format);
template<class InputIterator>
  path(InputIterator first, InputIterator last, const locale& loc, format fmt = auto_format);
`

[5](#fs.path.construct-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14196)

*Mandates*: The value type of Source and InputIterator ischar[.](#fs.path.construct-5.sentence-1)

[6](#fs.path.construct-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14201)

*Effects*: Let s be the effective range of source or the range [first, last),
after converting the encoding as
follows:

- [(6.1)](#fs.path.construct-6.1)

  If value_type is wchar_t, converts to the native
wide encoding ([[fs.path.type.cvt]](#fs.path.type.cvt "31.12.6.3.2 Type and encoding conversions")) using the codecvt<​wchar_t, char, mbstate_t> facet of loc[.](#fs.path.construct-6.1.sentence-1)

- [(6.2)](#fs.path.construct-6.2)

  Otherwise a conversion is performed using thecodecvt<wchar_t, char, mbstate_t> facet of loc, and then a second
conversion to the current ordinary encoding[.](#fs.path.construct-6.2.sentence-1)

[7](#fs.path.construct-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14218)

Finds the detected-format of s ([[fs.path.fmt.cvt]](#fs.path.fmt.cvt "31.12.6.3.1 Argument format conversions"))
and constructs an object of class path for which the pathname in that format is s[.](#fs.path.construct-7.sentence-1)

[*Example [1](#fs.path.construct-example-1)*:

A string is to be read from a database
that is encoded in ISO/IEC 8859-1, and used to create a directory:namespace fs = std::filesystem;
std::string latin1_string = read_latin1_data();
codecvt_8859_1<wchar_t> latin1_facet;
std::locale latin1_locale(std::locale(), latin1_facet);
fs::create_directory(fs::path(latin1_string, latin1_locale));

For POSIX-based operating systems, the path is constructed by first usinglatin1_facet to convert ISO/IEC 8859-1 encodedlatin1_string to a wide character string in the native wide
encoding ([[fs.path.type.cvt]](#fs.path.type.cvt "31.12.6.3.2 Type and encoding conversions"))[.](#fs.path.construct-7.sentence-3)

The resulting wide string is then
converted to an ordinary character
pathname string in the current native ordinary encoding[.](#fs.path.construct-7.sentence-4)

If the
native wide encoding is UTF-16 or UTF-32, and the current native ordinary
encoding is UTF-8, all of the characters in the ISO/IEC 8859-1 character set
will be converted to their Unicode representation, but for other native
ordinary encodings some characters may have no representation[.](#fs.path.construct-7.sentence-5)

For Windows-based operating systems, the path is constructed by
using latin1_facet to convert ISO/IEC 8859-1 encodedlatin1_string to a UTF-16 encoded wide character pathname
string[.](#fs.path.construct-7.sentence-6)

All of the characters in the ISO/IEC 8859-1 character set will be
converted to their Unicode representation[.](#fs.path.construct-7.sentence-7)

— *end example*]

#### [31.12.6.5.2](#fs.path.assign) Assignments [[fs.path.assign]](fs.path.assign)

[🔗](#lib:operator=,path)

`path& operator=(const path& p);
`

[1](#fs.path.assign-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14260)

*Effects*: If *this and p are the same
object, has no effect[.](#fs.path.assign-1.sentence-1)

Otherwise,
sets both respective pathnames of *this to the respective pathnames of p[.](#fs.path.assign-1.sentence-2)

[2](#fs.path.assign-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14268)

*Returns*: *this[.](#fs.path.assign-2.sentence-1)

[🔗](#lib:operator=,path_)

`path& operator=(path&& p) noexcept;
`

[3](#fs.path.assign-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14279)

*Effects*: If *this and p are the same
object, has no effect[.](#fs.path.assign-3.sentence-1)

Otherwise,
sets both respective pathnames of *this to the respective pathnames of p[.](#fs.path.assign-3.sentence-2)

p is left in a valid but unspecified state[.](#fs.path.assign-3.sentence-3)

[*Note [1](#fs.path.assign-note-1)*:

A valid implementation is swap(p)[.](#fs.path.assign-3.sentence-4)

— *end note*]

[4](#fs.path.assign-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14290)

*Returns*: *this[.](#fs.path.assign-4.sentence-1)

[🔗](#lib:operator=,path__)

`path& operator=(string_type&& source);
path& assign(string_type&& source);
`

[5](#fs.path.assign-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14303)

*Effects*: Sets the pathname in the detected-format of source to the original value of source[.](#fs.path.assign-5.sentence-1)

source is left in a valid but unspecified state[.](#fs.path.assign-5.sentence-2)

[6](#fs.path.assign-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14309)

*Returns*: *this[.](#fs.path.assign-6.sentence-1)

[🔗](#lib:operator=,path___)

`template<class Source>
  path& operator=(const Source& source);
template<class Source>
  path& assign(const Source& source);
template<class InputIterator>
  path& assign(InputIterator first, InputIterator last);
`

[7](#fs.path.assign-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14326)

*Effects*: Let s be the effective range of source ([[fs.path.req]](#fs.path.req "31.12.6.4 Requirements"))
or the range [first, last), with the encoding converted if required ([[fs.path.cvt]](#fs.path.cvt "31.12.6.3 Conversions"))[.](#fs.path.assign-7.sentence-1)

Finds the detected-format of s ([[fs.path.fmt.cvt]](#fs.path.fmt.cvt "31.12.6.3.1 Argument format conversions"))
and sets the pathname in that format to s[.](#fs.path.assign-7.sentence-2)

[8](#fs.path.assign-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14333)

*Returns*: *this[.](#fs.path.assign-8.sentence-1)

#### [31.12.6.5.3](#fs.path.append) Appends [[fs.path.append]](fs.path.append)

[1](#fs.path.append-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14340)

The append operations use operator/= to denote their semantic effect of appending[*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]") when needed[.](#fs.path.append-1.sentence-1)

[🔗](#lib:operator/=,path)

`path& operator/=(const path& p);
`

[2](#fs.path.append-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14350)

*Effects*: If p.is_absolute() || (p.has_root_name() && p.root_name() != root_name()),
then operator=(p)[.](#fs.path.append-2.sentence-1)

[3](#fs.path.append-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14355)

Otherwise, modifies *this as if by these steps:

- [(3.1)](#fs.path.append-3.1)

  If p.has_root_directory(),
 then removes any root directory and relative path
 from the generic format pathname[.](#fs.path.append-3.1.sentence-1)
  Otherwise,
 if !has_root_directory() && is_absolute() is true or if has_filename() is true,
 then appends path​::​preferred_separator to the generic format pathname[.](#fs.path.append-3.1.sentence-2)

- [(3.2)](#fs.path.append-3.2)

  Then appends the native format pathname of p,
 omitting any [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") from its generic format pathname,
 to the native format pathname[.](#fs.path.append-3.2.sentence-1)

[4](#fs.path.append-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14370)

[*Example [1](#fs.path.append-example-1)*:

Even if //host is interpreted as a [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]"),
both of the paths path("//host")/"foo" and path("//host/")/"foo" equal "//host/foo" (although the former might use backslash as the
preferred separator)[.](#fs.path.append-4.sentence-1)

Expression examples:// On POSIX, path("foo") /= path(""); // yields path("foo/") path("foo") /= path("/bar"); // yields path("/bar")// On Windows, path("foo") /= path(""); // yields path("foo\\") path("foo") /= path("/bar"); // yields path("/bar") path("foo") /= path("c:/bar"); // yields path("c:/bar") path("foo") /= path("c:"); // yields path("c:") path("c:") /= path(""); // yields path("c:") path("c:foo") /= path("/bar"); // yields path("c:/bar") path("c:foo") /= path("c:bar"); // yields path("c:foo\\bar")

— *end example*]

[5](#fs.path.append-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14394)

*Returns*: *this[.](#fs.path.append-5.sentence-1)

[🔗](#lib:operator/=,path_)

`template<class Source>
  path& operator/=(const Source& source);
template<class Source>
  path& append(const Source& source);
`

[6](#fs.path.append-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14409)

*Effects*: Equivalent to: return operator/=(path(source));

[🔗](#lib:operator/=,path__)

`template<class InputIterator>
  path& append(InputIterator first, InputIterator last);
`

[7](#fs.path.append-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14422)

*Effects*: Equivalent to: return operator/=(path(first, last));

#### [31.12.6.5.4](#fs.path.concat) Concatenation [[fs.path.concat]](fs.path.concat)

[🔗](#lib:operator+=,path)

`path& operator+=(const path& x);
path& operator+=(const string_type& x);
path& operator+=(basic_string_view<value_type> x);
path& operator+=(const value_type* x);
template<class Source>
  path& operator+=(const Source& x);
template<class Source>
  path& concat(const Source& x);
`

[1](#fs.path.concat-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14443)

*Effects*: Appends path(x).native() to the pathname in the native format[.](#fs.path.concat-1.sentence-1)

[*Note [1](#fs.path.concat-note-1)*:

This directly manipulates the value of native(),
which is not necessarily portable between operating systems[.](#fs.path.concat-1.sentence-2)

— *end note*]

[2](#fs.path.concat-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14451)

*Returns*: *this[.](#fs.path.concat-2.sentence-1)

[🔗](#lib:operator+=,path_)

`path& operator+=(value_type x);
template<class EcharT>
  path& operator+=(EcharT x);
`

[3](#fs.path.concat-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14465)

*Effects*: Equivalent to: return *this += basic_string_view(&x, 1);

[🔗](#lib:concat,path__)

`template<class InputIterator>
  path& concat(InputIterator first, InputIterator last);
`

[4](#fs.path.concat-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14477)

*Effects*: Equivalent to: return *this += path(first, last);

#### [31.12.6.5.5](#fs.path.modifiers) Modifiers [[fs.path.modifiers]](fs.path.modifiers)

[🔗](#lib:clear,path)

`void clear() noexcept;
`

[1](#fs.path.modifiers-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14490)

*Postconditions*: empty() is true[.](#fs.path.modifiers-1.sentence-1)

[🔗](#lib:make_preferred,path)

`path& make_preferred();
`

[2](#fs.path.modifiers-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14501)

*Effects*: Each [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") of the pathname in the generic format
is converted to [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.modifiers-2.sentence-1)

[3](#fs.path.modifiers-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14507)

*Returns*: *this[.](#fs.path.modifiers-3.sentence-1)

[4](#fs.path.modifiers-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14511)

[*Example [1](#fs.path.modifiers-example-1)*: path p("foo/bar");
std::cout << p << '\n';
p.make_preferred();
std::cout << p << '\n';

On an operating system where [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]") is a slash,
the output is:"foo/bar""foo/bar"

On an operating system where [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]") is a backslash, the
output is:"foo/bar""foo\bar"

— *end example*]

[🔗](#lib:remove_filename,path)

`path& remove_filename();
`

[5](#fs.path.modifiers-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14540)

*Effects*: Remove the generic format pathname of filename() from the generic format pathname[.](#fs.path.modifiers-5.sentence-1)

[6](#fs.path.modifiers-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14544)

*Postconditions*: !has_filename()[.](#fs.path.modifiers-6.sentence-1)

[7](#fs.path.modifiers-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14548)

*Returns*: *this[.](#fs.path.modifiers-7.sentence-1)

[8](#fs.path.modifiers-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14552)

[*Example [2](#fs.path.modifiers-example-2)*: path("foo/bar").remove_filename(); // yields "foo/" path("foo/").remove_filename(); // yields "foo/" path("/foo").remove_filename(); // yields "/" path("/").remove_filename(); // yields "/" — *end example*]

[🔗](#lib:replace_filename,path)

`path& replace_filename(const path& replacement);
`

[9](#fs.path.modifiers-9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14569)

*Effects*: Equivalent to:remove_filename();operator/=(replacement);

[10](#fs.path.modifiers-10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14577)

*Returns*: *this[.](#fs.path.modifiers-10.sentence-1)

[11](#fs.path.modifiers-11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14581)

[*Example [3](#fs.path.modifiers-example-3)*: path("/foo").replace_filename("bar"); // yields "/bar" on POSIX path("/").replace_filename("bar"); // yields "/bar" on POSIX — *end example*]

[🔗](#lib:replace_extension,path)

`path& replace_extension(const path& replacement = path());
`

[12](#fs.path.modifiers-12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14596)

*Effects*: 

- [(12.1)](#fs.path.modifiers-12.1)

Any existing extension() ([[fs.path.decompose]](#fs.path.decompose "31.12.6.5.9 Decomposition")) is removed from the
 pathname in the generic format,
 then

- [(12.2)](#fs.path.modifiers-12.2)

If replacement is not empty and does not begin with a dot
 character, a dot character is appended to the pathname in the generic format, then

- [(12.3)](#fs.path.modifiers-12.3)

operator+=(replacement);[.](#fs.path.modifiers-12.sentence-1)

[13](#fs.path.modifiers-13)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14608)

*Returns*: *this[.](#fs.path.modifiers-13.sentence-1)

[🔗](#lib:swap,path)

`void swap(path& rhs) noexcept;
`

[14](#fs.path.modifiers-14)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14619)

*Effects*: Swaps the contents (in all formats) of the two paths[.](#fs.path.modifiers-14.sentence-1)

[15](#fs.path.modifiers-15)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14623)

*Complexity*: Constant time[.](#fs.path.modifiers-15.sentence-1)

#### [31.12.6.5.6](#fs.path.native.obs) Native format observers [[fs.path.native.obs]](fs.path.native.obs)

[1](#fs.path.native.obs-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14630)

The string returned by all native format observers is in the native pathname format ([fs.class.path])[.](#fs.path.native.obs-1.sentence-1)

[🔗](#lib:native,path)

`const string_type& native() const noexcept;
`

[2](#fs.path.native.obs-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14639)

*Returns*: The pathname in the native format[.](#fs.path.native.obs-2.sentence-1)

[🔗](#lib:c_str,path)

`const value_type* c_str() const noexcept;
`

[3](#fs.path.native.obs-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14650)

*Effects*: Equivalent to: return native().c_str();

[🔗](#lib:operator_string_type,path)

`operator string_type() const;
`

[4](#fs.path.native.obs-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14661)

*Returns*: native()[.](#fs.path.native.obs-4.sentence-1)

[🔗](#lib:string,path)

`template<class EcharT, class traits = char_traits<EcharT>, class Allocator = allocator<EcharT>>
  basic_string<EcharT, traits, Allocator> string(const Allocator& a = Allocator()) const;
`

[5](#fs.path.native.obs-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14673)

*Returns*: native()[.](#fs.path.native.obs-5.sentence-1)

[6](#fs.path.native.obs-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14677)

*Remarks*: All memory allocation, including for the return value, shall
be performed by a[.](#fs.path.native.obs-6.sentence-1)

Conversion, if any, is specified by[[fs.path.cvt]](#fs.path.cvt "31.12.6.3 Conversions")[.](#fs.path.native.obs-6.sentence-2)

[🔗](#lib:system_encoded_string,path)

`std::string system_encoded_string() const;
std::wstring wstring() const;
std::u8string u8string() const;
std::u16string u16string() const;
std::u32string u32string() const;
`

[7](#fs.path.native.obs-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14698)

*Returns*: native()[.](#fs.path.native.obs-7.sentence-1)

[8](#fs.path.native.obs-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14702)

*Remarks*: Conversion, if any, is performed as specified
by [[fs.path.cvt]](#fs.path.cvt "31.12.6.3 Conversions")[.](#fs.path.native.obs-8.sentence-1)

[🔗](#lib:display_string,path)

`std::string display_string() const;
`

[9](#fs.path.native.obs-9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14714)

*Returns*: format("{}", *this)[.](#fs.path.native.obs-9.sentence-1)

[*Note [1](#fs.path.native.obs-note-1)*:

The returned string is suitable for use with formatting ([[format.functions]](format.functions "28.5.5 Formatting functions"))
and print functions ([[print.fun]](print.fun "31.7.10 Print functions"))[.](#fs.path.native.obs-9.sentence-2)

— *end note*]

#### [31.12.6.5.7](#fs.path.generic.obs) Generic format observers [[fs.path.generic.obs]](fs.path.generic.obs)

[1](#fs.path.generic.obs-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14725)

Generic format observer functions return strings formatted according to the[generic pathname format](#fs.path.generic "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.generic.obs-1.sentence-1)

A single slash ('/') character is used as
the [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.generic.obs-1.sentence-2)

[2](#fs.path.generic.obs-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14731)

[*Example [1](#fs.path.generic.obs-example-1)*:

On an operating system that uses backslash as
its [*preferred-separator*](#nt:preferred-separator "31.12.6.2 Generic pathname format [fs.path.generic]"),path("foo\\bar").generic_string() returns "foo/bar"[.](#fs.path.generic.obs-2.sentence-1)

— *end example*]

[🔗](#lib:generic_string,path)

`template<class EcharT, class traits = char_traits<EcharT>, class Allocator = allocator<EcharT>>
  basic_string<EcharT, traits, Allocator> generic_string(const Allocator& a = Allocator()) const;
`

[3](#fs.path.generic.obs-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14748)

*Returns*: The pathname in the generic format[.](#fs.path.generic.obs-3.sentence-1)

[4](#fs.path.generic.obs-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14752)

*Remarks*: All memory allocation, including for the return value, shall
be performed by a[.](#fs.path.generic.obs-4.sentence-1)

Conversion, if any, is specified by[[fs.path.cvt]](#fs.path.cvt "31.12.6.3 Conversions")[.](#fs.path.generic.obs-4.sentence-2)

[🔗](#lib:generic_system_encoded_string,path)

`std::string generic_system_encoded_string() const;
std::wstring generic_wstring() const;
std::u8string generic_u8string() const;
std::u16string generic_u16string() const;
std::u32string generic_u32string() const;
`

[5](#fs.path.generic.obs-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14773)

*Returns*: The pathname in the generic format[.](#fs.path.generic.obs-5.sentence-1)

[6](#fs.path.generic.obs-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14777)

*Remarks*: Conversion, if any, is specified by [[fs.path.cvt]](#fs.path.cvt "31.12.6.3 Conversions")[.](#fs.path.generic.obs-6.sentence-1)

[🔗](#lib:generic_display_string,path)

`std::string generic_display_string() const;
`

[7](#fs.path.generic.obs-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14788)

*Returns*: format("{:g}", *this)[.](#fs.path.generic.obs-7.sentence-1)

[*Note [1](#fs.path.generic.obs-note-1)*:

The returned string is suitable for use with formatting ([[format.functions]](format.functions "28.5.5 Formatting functions"))
and print functions ([[print.fun]](print.fun "31.7.10 Print functions"))[.](#fs.path.generic.obs-7.sentence-2)

— *end note*]

#### [31.12.6.5.8](#fs.path.compare) Compare [[fs.path.compare]](fs.path.compare)

[🔗](#lib:compare,path)

`int compare(const path& p) const noexcept;
`

[1](#fs.path.compare-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14805)

*Returns*: 

- [(1.1)](#fs.path.compare-1.1)

  Let rootNameComparison be the result of this->root_name().native().compare(p.root_name().native())[.](#fs.path.compare-1.1.sentence-1)
  If rootNameComparison is not 0, rootNameComparison[.](#fs.path.compare-1.1.sentence-2)

- [(1.2)](#fs.path.compare-1.2)

  Otherwise, if !this->has_root_directory() and p.has_root_directory(),
 a value less than 0[.](#fs.path.compare-1.2.sentence-1)

- [(1.3)](#fs.path.compare-1.3)

  Otherwise, if this->has_root_directory() and !p.has_root_directory(),
 a value greater than 0[.](#fs.path.compare-1.3.sentence-1)

- [(1.4)](#fs.path.compare-1.4)

  Otherwise, if native() for the elements of this->relative_path() are lexicographically less than native() for the elements of p.relative_path(),
 a value less than 0[.](#fs.path.compare-1.4.sentence-1)

- [(1.5)](#fs.path.compare-1.5)

  Otherwise, if native() for the elements of this->relative_path() are lexicographically greater than native() for the elements of p.relative_path(),
 a value greater than 0[.](#fs.path.compare-1.5.sentence-1)

- [(1.6)](#fs.path.compare-1.6)

  Otherwise, 0[.](#fs.path.compare-1.6.sentence-1)

[🔗](#lib:compare,path_)

`int compare(const string_type& s) const;
int compare(basic_string_view<value_type> s) const;
int compare(const value_type* s) const;
`

[2](#fs.path.compare-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14846)

*Effects*: Equivalent to: return compare(path(s));

#### [31.12.6.5.9](#fs.path.decompose) Decomposition [[fs.path.decompose]](fs.path.decompose)

[🔗](#lib:root_name,path)

`path root_name() const;
`

[1](#fs.path.decompose-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14859)

*Returns*: [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]"), if the pathname in the generic format
includes [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]"), otherwise path()[.](#fs.path.decompose-1.sentence-1)

[🔗](#lib:root_directory,path)

`path root_directory() const;
`

[2](#fs.path.decompose-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14871)

*Returns*: [*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]"), if the pathname in the generic format
includes [*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]"), otherwise path()[.](#fs.path.decompose-2.sentence-1)

[🔗](#lib:root_path,path)

`path root_path() const;
`

[3](#fs.path.decompose-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14883)

*Returns*: root_name() / root_directory()[.](#fs.path.decompose-3.sentence-1)

[🔗](#lib:relative_path,path)

`path relative_path() const;
`

[4](#fs.path.decompose-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14894)

*Returns*: A path composed from the pathname in the generic format,
if empty() is false, beginning
with the first [*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") after root_path()[.](#fs.path.decompose-4.sentence-1)

Otherwise, path()[.](#fs.path.decompose-4.sentence-2)

[🔗](#lib:parent_path,path)

`path parent_path() const;
`

[5](#fs.path.decompose-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14907)

*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[.](#fs.path.decompose-5.sentence-1)

[🔗](#lib:filename,path)

`path filename() const;
`

[6](#fs.path.decompose-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14921)

*Returns*: relative_path().empty() ? path() : *--end()[.](#fs.path.decompose-6.sentence-1)

[7](#fs.path.decompose-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14925)

[*Example [1](#fs.path.decompose-example-1)*: 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*]

[🔗](#lib:stem,path)

`path stem() const;
`

[8](#fs.path.decompose-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14945)

*Returns*: Let f be the generic format pathname of filename()[.](#fs.path.decompose-8.sentence-1)

Returns a path whose pathname in the generic format is

- [(8.1)](#fs.path.decompose-8.1)

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

- [(8.2)](#fs.path.decompose-8.2)

otherwise, the prefix of f ending before its last period[.](#fs.path.decompose-8.sentence-2)

[9](#fs.path.decompose-9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14955)

[*Example [2](#fs.path.decompose-example-2)*: 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*]

[🔗](#lib:extension,path)

`path extension() const;
`

[10](#fs.path.decompose-10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14975)

*Returns*: A path whose pathname in the generic format is
the suffix of filename() not included in stem()[.](#fs.path.decompose-10.sentence-1)

[11](#fs.path.decompose-11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14980)

[*Example [3](#fs.path.decompose-example-3)*: 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*]

[12](#fs.path.decompose-12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14991)

[*Note [1](#fs.path.decompose-note-1)*:

The period is included in the return value so that it is
 possible to distinguish between no extension and an empty extension[.](#fs.path.decompose-12.sentence-1)

— *end note*]

[13](#fs.path.decompose-13)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L14997)

[*Note [2](#fs.path.decompose-note-2)*:

On non-POSIX operating systems, for a path p,
it is possible that p.stem() + p.extension() == p.filename() is false,
even though the generic format pathnames are the same[.](#fs.path.decompose-13.sentence-1)

— *end note*]

#### [31.12.6.5.10](#fs.path.query) Query [[fs.path.query]](fs.path.query)

[🔗](#lib:empty,path)

`bool empty() const noexcept;
`

[1](#fs.path.query-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15013)

*Returns*: true if the pathname in the generic format is empty, otherwise false[.](#fs.path.query-1.sentence-1)

[🔗](#lib:has_root_path,path)

`bool has_root_path() const;
`

[2](#fs.path.query-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15024)

*Returns*: !root_path().empty()[.](#fs.path.query-2.sentence-1)

[🔗](#lib:has_root_name,path)

`bool has_root_name() const;
`

[3](#fs.path.query-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15035)

*Returns*: !root_name().empty()[.](#fs.path.query-3.sentence-1)

[🔗](#lib:has_root_directory,path)

`bool has_root_directory() const;
`

[4](#fs.path.query-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15046)

*Returns*: !root_directory().empty()[.](#fs.path.query-4.sentence-1)

[🔗](#lib:has_relative_path,path)

`bool has_relative_path() const;
`

[5](#fs.path.query-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15057)

*Returns*: !relative_path().empty()[.](#fs.path.query-5.sentence-1)

[🔗](#lib:has_parent_path,path)

`bool has_parent_path() const;
`

[6](#fs.path.query-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15068)

*Returns*: !parent_path().empty()[.](#fs.path.query-6.sentence-1)

[🔗](#lib:has_filename,path)

`bool has_filename() const;
`

[7](#fs.path.query-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15079)

*Returns*: !filename().empty()[.](#fs.path.query-7.sentence-1)

[🔗](#lib:has_stem,path)

`bool has_stem() const;
`

[8](#fs.path.query-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15090)

*Returns*: !stem().empty()[.](#fs.path.query-8.sentence-1)

[🔗](#lib:has_extension,path)

`bool has_extension() const;
`

[9](#fs.path.query-9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15101)

*Returns*: !extension().empty()[.](#fs.path.query-9.sentence-1)

[🔗](#lib:is_absolute,path)

`bool is_absolute() const;
`

[10](#fs.path.query-10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15112)

*Returns*: true if the pathname in the native format
 contains an absolute path ([fs.class.path]), otherwise false[.](#fs.path.query-10.sentence-1)

[11](#fs.path.query-11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15117)

[*Example [1](#fs.path.query-example-1)*:

path("/").is_absolute() is true for POSIX-based operating systems, and false for Windows-based
operating systems[.](#fs.path.query-11.sentence-1)

— *end example*]

[🔗](#lib:is_relative,path)

`bool is_relative() const;
`

[12](#fs.path.query-12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15131)

*Returns*: !is_absolute()[.](#fs.path.query-12.sentence-1)

#### [31.12.6.5.11](#fs.path.gen) Generation [[fs.path.gen]](fs.path.gen)

[🔗](#lib:lexically_normal,path)

`path lexically_normal() const;
`

[1](#fs.path.gen-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15144)

*Returns*: A path whose pathname in the generic format is
the normal form ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format")) of the pathname
in the generic format of *this[.](#fs.path.gen-1.sentence-1)

[2](#fs.path.gen-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15150)

[*Example [1](#fs.path.gen-example-1)*: assert(path("foo/./bar/..").lexically_normal() == "foo/");
assert(path("foo/.///bar/../").lexically_normal() == "foo/");

The above assertions will succeed[.](#fs.path.gen-2.sentence-1)

On Windows, the returned path's [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") characters
will be backslashes rather than slashes,
but that does not affect path equality[.](#fs.path.gen-2.sentence-2)

— *end example*]

[🔗](#lib:lexically_relative,path)

`path lexically_relative(const path& base) const;
`

[3](#fs.path.gen-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15169)

*Effects*: If:

- [(3.1)](#fs.path.gen-3.1)

root_name() != base.root_name() is true, or

- [(3.2)](#fs.path.gen-3.2)

is_absolute() != base.is_absolute() is true, or

- [(3.3)](#fs.path.gen-3.3)

!has_root_directory() && base.has_root_directory() is true, or

- [(3.4)](#fs.path.gen-3.4)

any [*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") inrelative_path() or base.relative_path() can be interpreted as a [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]"),

returns path()[.](#fs.path.gen-3.sentence-1)

[*Note [1](#fs.path.gen-note-1)*:

On a POSIX implementation, no [*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") in a [*relative-path*](#nt:relative-path "31.12.6.2 Generic pathname format [fs.path.generic]") is acceptable as a [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.gen-3.sentence-2)

— *end note*]

Determines the first mismatched element of *this and base as if by:auto [a, b] = mismatch(begin(), end(), base.begin(), base.end());

Then,

- [(3.5)](#fs.path.gen-3.5)

  if a == end() and b == base.end(), returns path("."); otherwise

- [(3.6)](#fs.path.gen-3.6)

  let n be the number of [*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") elements in [b, base.end())
 that are not dot or dot-dot or empty, minus the number that are dot-dot[.](#fs.path.gen-3.6.sentence-1)
  If n<0, returns path(); otherwise

- [(3.7)](#fs.path.gen-3.7)

  if n == 0 and (a == end() || a->empty()),
 returns path("."); otherwise

- [(3.8)](#fs.path.gen-3.8)

  returns an object of class path that is default-constructed, followed by
  * [(3.8.1)](#fs.path.gen-3.8.1)

application of operator/=(path(".."))n times, and then

  * [(3.8.2)](#fs.path.gen-3.8.2)

application of operator/= for each element in [a, end())[.](#fs.path.gen-3.8.sentence-1)

[4](#fs.path.gen-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15215)

*Returns*: *this made relative to base[.](#fs.path.gen-4.sentence-1)

Does not resolve ([fs.class.path]) symlinks[.](#fs.path.gen-4.sentence-2)

Does not first normalize ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format")) *this or base[.](#fs.path.gen-4.sentence-3)

[5](#fs.path.gen-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15221)

[*Example [2](#fs.path.gen-example-2)*: assert(path("/a/d").lexically_relative("/a/b/c") == "../../d");
assert(path("/a/b/c").lexically_relative("/a/d") == "../b/c");
assert(path("a/b/c").lexically_relative("a") == "b/c");
assert(path("a/b/c").lexically_relative("a/b/c/x/y") == "../..");
assert(path("a/b/c").lexically_relative("a/b/c") == ".");
assert(path("a/b").lexically_relative("c/d") == "../../a/b");

The above assertions will succeed[.](#fs.path.gen-5.sentence-1)

On Windows, the returned path's [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") characters
will be backslashes rather than slashes,
but that does not affect path equality[.](#fs.path.gen-5.sentence-2)

— *end example*]

[6](#fs.path.gen-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15237)

[*Note [2](#fs.path.gen-note-2)*:

If symlink following semantics are desired,
 use the operational function relative()[.](#fs.path.gen-6.sentence-1)

— *end note*]

[7](#fs.path.gen-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15243)

[*Note [3](#fs.path.gen-note-3)*:

If normalization ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format")) is needed
 to ensure consistent matching of elements,
 apply lexically_normal() to *this, base, or both[.](#fs.path.gen-7.sentence-1)

— *end note*]

[🔗](#lib:lexically_proximate,path)

`path lexically_proximate(const path& base) const;
`

[8](#fs.path.gen-8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15258)

*Returns*: If the value of lexically_relative(base) is not an empty path,
 return it[.](#fs.path.gen-8.sentence-1)

Otherwise return *this[.](#fs.path.gen-8.sentence-2)

[9](#fs.path.gen-9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15263)

[*Note [4](#fs.path.gen-note-4)*:

If symlink following semantics are desired,
 use the operational function proximate()[.](#fs.path.gen-9.sentence-1)

— *end note*]

[10](#fs.path.gen-10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15269)

[*Note [5](#fs.path.gen-note-5)*:

If normalization ([[fs.path.generic]](#fs.path.generic "31.12.6.2 Generic pathname format")) is needed
 to ensure consistent matching of elements,
 apply lexically_normal() to *this, base, or both[.](#fs.path.gen-10.sentence-1)

— *end note*]

#### [31.12.6.6](#fs.path.itr) Iterators [[fs.path.itr]](fs.path.itr)

[1](#fs.path.itr-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15281)

Path iterators iterate over the elements of the pathname
in the [generic format](#fs.path.generic "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#fs.path.itr-1.sentence-1)

[2](#fs.path.itr-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15285)

A path​::​iterator is a constant iterator meeting all the
requirements of a [bidirectional iterator](bidirectional.iterators "24.3.5.6 Bidirectional iterators [bidirectional.iterators]") except that,
for dereferenceable iterators a and b of type path​::​iterator with a == b,
there is no requirement that *a and *b are bound to the same object[.](#fs.path.itr-2.sentence-1)

Its value_type is path[.](#fs.path.itr-2.sentence-2)

[3](#fs.path.itr-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15296)

Calling any non-const member function of a path object
invalidates all iterators referring to elements of that object[.](#fs.path.itr-3.sentence-1)

[4](#fs.path.itr-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15300)

For the elements of the pathname in the generic format,
the forward traversal order is as follows:

- [(4.1)](#fs.path.itr-4.1)

  The [*root-name*](#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") element, if present[.](#fs.path.itr-4.1.sentence-1)

- [(4.2)](#fs.path.itr-4.2)

  The [*root-directory*](#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]") element, if present[.](#fs.path.itr-4.2.sentence-1)
  [*Note [1](#fs.path.itr-note-1)*:
  It is possible that the use of the generic format is needed
to ensure correct lexicographical comparison[.](#fs.path.itr-4.2.sentence-2)
 — *end note*]

- [(4.3)](#fs.path.itr-4.3)

  Each successive [*filename*](#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") element, if present[.](#fs.path.itr-4.3.sentence-1)

- [(4.4)](#fs.path.itr-4.4)

  An empty element, if a trailing non-root [*directory-separator*](#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") is present[.](#fs.path.itr-4.4.sentence-1)

[5](#fs.path.itr-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15315)

The backward traversal order is the reverse of forward traversal[.](#fs.path.itr-5.sentence-1)

[🔗](#lib:begin,path)

`iterator begin() const;
`

[6](#fs.path.itr-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15324)

*Returns*: An iterator for the first present element in the traversal
list above[.](#fs.path.itr-6.sentence-1)

If no elements are present, the end iterator[.](#fs.path.itr-6.sentence-2)

[🔗](#lib:end,path)

`iterator end() const;
`

[7](#fs.path.itr-7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15336)

*Returns*: The end iterator[.](#fs.path.itr-7.sentence-1)

#### [31.12.6.7](#fs.path.io) Inserter and extractor [[fs.path.io]](fs.path.io)

[🔗](#lib:operator%3c%3c,path)

`template<class charT, class traits>
  friend basic_ostream<charT, traits>&
    operator<<(basic_ostream<charT, traits>& os, const path& p);
`

[1](#fs.path.io-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15351)

*Effects*: Equivalent to os << quoted(p.string<charT, traits>())[.](#fs.path.io-1.sentence-1)

[*Note [1](#fs.path.io-note-1)*:

The quoted function is described in [[quoted.manip]](quoted.manip "31.7.9 Quoted manipulators")[.](#fs.path.io-1.sentence-2)

— *end note*]

[2](#fs.path.io-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15358)

*Returns*: os[.](#fs.path.io-2.sentence-1)

[🔗](#lib:operator%3e%3e,path)

`template<class charT, class traits>
  friend basic_istream<charT, traits>&
    operator>>(basic_istream<charT, traits>& is, path& p);
`

[3](#fs.path.io-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15371)

*Effects*: Equivalent to:basic_string<charT, traits> tmp;
is >> quoted(tmp);
p = tmp;

[4](#fs.path.io-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15380)

*Returns*: is[.](#fs.path.io-4.sentence-1)

#### [31.12.6.8](#fs.path.nonmember) Non-member functions [[fs.path.nonmember]](fs.path.nonmember)

[🔗](#lib:swap,path_)

`void swap(path& lhs, path& rhs) noexcept;
`

[1](#fs.path.nonmember-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15393)

*Effects*: Equivalent to lhs.swap(rhs)[.](#fs.path.nonmember-1.sentence-1)

[🔗](#lib:hash_value,path)

`size_t hash_value(const path& p) noexcept;
`

[2](#fs.path.nonmember-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15404)

*Returns*: A hash value for the path p[.](#fs.path.nonmember-2.sentence-1)

If
 for two paths, p1 == p2 then hash_value(p1) == hash_value(p2)[.](#fs.path.nonmember-2.sentence-2)

[🔗](#lib:operator==,path)

`friend bool operator==(const path& lhs, const path& rhs) noexcept;
`

[3](#fs.path.nonmember-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15416)

*Returns*: lhs.compare(rhs) == 0[.](#fs.path.nonmember-3.sentence-1)

[4](#fs.path.nonmember-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15421)

[*Note [1](#fs.path.nonmember-note-1)*:

Path equality and path equivalence have different semantics[.](#fs.path.nonmember-4.sentence-1)

- [(4.1)](#fs.path.nonmember-4.1)

  Equality is determined by the path non-member operator==,
which considers the two paths' lexical representations only[.](#fs.path.nonmember-4.1.sentence-1)
  [*Example [1](#fs.path.nonmember-example-1)*:
  path("foo") == "bar" is never true[.](#fs.path.nonmember-4.1.sentence-2)
 — *end example*]

- [(4.2)](#fs.path.nonmember-4.2)

  Equivalence is determined by the equivalent() non-member function, which
determines if two paths resolve ([fs.class.path]) to the same file system entity[.](#fs.path.nonmember-4.2.sentence-1)
  [*Example [2](#fs.path.nonmember-example-2)*:
  equivalent("foo", "bar") will be true when both paths resolve to the same file[.](#fs.path.nonmember-4.2.sentence-2)
 — *end example*]

— *end note*]

[🔗](#lib:operator%3c=%3e,path)

`friend strong_ordering operator<=>(const path& lhs, const path& rhs) noexcept;
`

[5](#fs.path.nonmember-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15445)

*Returns*: lhs.compare(rhs) <=> 0[.](#fs.path.nonmember-5.sentence-1)

[🔗](#lib:operator/,path)

`friend path operator/(const path& lhs, const path& rhs);
`

[6](#fs.path.nonmember-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15456)

*Effects*: Equivalent to: return path(lhs) /= rhs;

#### [31.12.6.9](#fs.path.fmtr) Formatting support [[fs.path.fmtr]](fs.path.fmtr)

#### [31.12.6.9.1](#fs.path.fmtr.general) Formatting support overview [[fs.path.fmtr.general]](fs.path.fmtr.general)

[🔗](#lib:formatter)

namespace std {template<class charT> struct formatter<filesystem::path, charT> {constexpr void set_debug_format(); constexpr typename basic_format_parse_context<charT>::iterator
 parse(basic_format_parse_context<charT>& ctx); template<class FormatContext>typename FormatContext::iterator
 format(const filesystem::path& path, FormatContext& ctx) const; };}

#### [31.12.6.9.2](#fs.path.fmtr.funcs) Formatting support functions [[fs.path.fmtr.funcs]](fs.path.fmtr.funcs)

[1](#fs.path.fmtr.funcs-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15483)

Formatting of paths uses formatting specifiers of the form

[path-format-spec:](#nt:path-format-spec "31.12.6.9.2 Formatting support functions [fs.path.fmtr.funcs]")  
fill-and-alignopt widthopt ?opt gopt

where the productions *fill-and-align* and *width* are described in [[format.string]](format.string "28.5.2 Format string")[.](#fs.path.fmtr.funcs-1.sentence-1)

If the ? option is used then
the path is formatted as an escaped string ([[format.string.escaped]](format.string.escaped "28.5.6.5 Formatting escaped characters and strings"))[.](#fs.path.fmtr.funcs-1.sentence-2)

[🔗](#lib:formatter,set_debug_format)

`constexpr void set_debug_format();
`

[2](#fs.path.fmtr.funcs-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15500)

*Effects*: Modifies the state of the formatter to be as if
the *path-format-spec* parsed by the last call to parse contained the ? option[.](#fs.path.fmtr.funcs-2.sentence-1)

[🔗](#lib:formatter,basic_format_parse_context)

`constexpr typename basic_format_parse_context<charT>::iterator
  parse(basic_format_parse_context<charT>& ctx);
`

[3](#fs.path.fmtr.funcs-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15514)

*Effects*: Parses the format specifier as a *path-format-spec* and
stores the parsed specifiers in *this[.](#fs.path.fmtr.funcs-3.sentence-1)

[4](#fs.path.fmtr.funcs-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15519)

*Returns*: An iterator past the end of the *path-format-spec*[.](#fs.path.fmtr.funcs-4.sentence-1)

[🔗](#lib:formatter,format)

`template<class FormatContext>
  typename FormatContext::iterator
    format(const filesystem::path& p, FormatContext& ctx) const;
`

[5](#fs.path.fmtr.funcs-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15532)

*Effects*: Let s be p.generic_string<filesystem​::​path​::​value_type>() if the g option is used,
otherwise p.native()[.](#fs.path.fmtr.funcs-5.sentence-1)

Writes s into ctx.out(),
adjusted according to the *path-format-spec*[.](#fs.path.fmtr.funcs-5.sentence-2)

If charT is char,path​::​value_type is wchar_t, and
the literal encoding is UTF-8,
then the escaped path is transcoded from the native encoding for
wide character strings to UTF-8 with
maximal subparts of ill-formed subsequences
substituted with U+fffd replacement character per the Unicode Standard, Chapter 3.9 U+fffd Substitution in Conversion[.](#fs.path.fmtr.funcs-5.sentence-3)

If charT and path​::​value_type are the same
then no transcoding is performed[.](#fs.path.fmtr.funcs-5.sentence-4)

Otherwise, transcoding isimplementation-defined[.](#fs.path.fmtr.funcs-5.sentence-5)

[6](#fs.path.fmtr.funcs-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15552)

*Returns*: An iterator past the end of the output range[.](#fs.path.fmtr.funcs-6.sentence-1)

#### [31.12.6.10](#fs.path.hash) Hash support [[fs.path.hash]](fs.path.hash)

[🔗](#fs.path.hash-itemdecl:1)

`template<> struct hash<filesystem::path>;
`

[1](#fs.path.hash-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15564)

For an object p of type filesystem​::​path,hash<filesystem​::​path>()(p) evaluates to the same result asfilesystem​::​hash_value(p)[.](#fs.path.hash-1.sentence-1)