Standard library header <filesystem>

 

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Filesystem library (C++17)

Technical Specifications

 

Standard Library header files

Language Support
<cstddef> <limits> <climits>	<cfloat> <cstdint> <new>	<typeinfo> <exception> <initializer_list>	<csignal> <csetjmp> <cstdarg>
Diagnostics
<stdexcept>	<cassert>	<cerrno>	<system_error>
General utilities
<utility> <memory> <memory_resource> <scoped_allocator>	<tuple> <optional> <any> <variant>	<bitset> <functional> <type_traits> <ratio>	<chrono> <ctime> <typeindex> <cstdlib>
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<string> <string_view>	<cctype> <cwctype>	<cwchar> <cuchar>	<cstring>
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<locale>	<codecvt>	<clocale>
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<array> <deque> <vector>	<forward_list> <list>	<map> <set> <queue>	<unordered_map> <unordered_set> <stack>
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<iterator>
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<algorithm>	<execution_policy>
Numerics
<complex> <random>	<valarray> <numeric>	<cfenv> <cmath>
Input/Output
<iosfwd> <iostream> <ios>	<streambuf> <istream> <ostream>	<iomanip> <sstream> <fstream>	<filesystem> <cstdio> <cinttypes>
Regular expressions
<regex>
Thread support
<thread> <atomic>	<mutex> <shared_mutex>	<condition_variable> <future>
C compatibility
<ciso646> <cstdalign>	<cstdbool> <ccomplex>	<ctgmath>

 

This header is part of the filesystem support library.

Defined in namespace filesystem
Classes
path (C++17)	represents a path (class)
filesystem_error (C++17)	an exception thrown on file system errors (class)
directory_entry (C++17)	a directory entry (class)
directory_iterator (C++17)	an iterator to the contents of the directory (class)
recursive_directory_iterator (C++17)	an iterator to the contents of a directory and its subdirectories (class)
file_status (C++17)	represents file type and permissions (class)
space_info (C++17)	information about free and available space on the filesystem (class)
file_type (C++17)	the type of a file (enum)
perms (C++17)	identifies file system permissions (enum)
copy_options (C++17)	specifies semantics of copy operations (enum)
directory_options (C++17)	options for iterating directory contents (enum)
file_time_type (C++17)	represents file time values (typedef)
Functions
u8path (C++17)	creates a path from a UTF-8 encoded source (function)
absolutesystem_complete (C++17)(C++17)	composes an absolute path converts a path to an absolute path replicating OS-specific behavior (function)
canonicalweakly_canonical (C++17)	composes a canonical path (function)
relativeproximate (C++17)	composes a relative path (function)
copy (C++17)	copies files or directories (function)
copy_file (C++17)	copies file contents (function)
copy_symlink (C++17)	copies a symbolic link (function)
create_directorycreate_directories (C++17)(C++17)	creates new directory (function)
create_hard_link (C++17)	creates a hard link (function)
create_symlinkcreate_directory_symlink (C++17)(C++17)	creates a symbolic link (function)
current_path (C++17)	return current working directory (function)
exists (C++17)	checks whether path refers to existing file system object (function)
equivalent (C++17)	checks whether two paths refer to the same file system object (function)
file_size (C++17)	returns the size of a file (function)
hard_link_count (C++17)	returns the number of hard links referring to the specific file (function)
last_write_time (C++17)	gets or sets the time of the last data modification (function)
permissions (C++17)	modifies file access permissions (function)
read_symlink (C++17)	obtains the target of a symbolic link (function)
removeremove_all (C++17)(C++17)	removes a file or empty directory removes a file or directory and all its contents, recursively (function)
rename (C++17)	moves or renames a file or directory (function)
resize_file (C++17)	changes the size of a regular file by truncation or zero-fill (function)
space (C++17)	determines available free space on the file system (function)
statussymlink_status (C++17)(C++17)	determines file attributes determines file attributes, checking the symlink target (function)
temp_directory_path (C++17)	returns a directory suitable for temporary files (function)
File types
is_block_file (C++17)	checks whether the given path refers to block device (function)
is_character_file (C++17)	checks whether the given path refers to a character device (function)
is_directory (C++17)	checks whether the given path refers to a directory (function)
is_empty (C++17)	checks whether the given path refers to an empty file or directory (function)
is_fifo (C++17)	checks whether the given path refers to a named pipe (function)
is_other (C++17)	checks whether the argument refers to an other file (function)
is_regular_file (C++17)	checks whether the argument refers to a regular file (function)
is_socket (C++17)	checks whether the argument refers to a named IPC socket (function)
is_symlink (C++17)	checks whether the argument refers to a symbolic link (function)
status_known (C++17)	checks whether file status is known (function)

Synopsis

namespace std::filesystem {
  // paths
  class path;
  // path non-member functions
  void swap(path& lhs, path& rhs) noexcept;
  size_t hash_value(const path& p) noexcept;
  bool operator==(const path& lhs, const path& rhs) noexcept;
  bool operator!=(const path& lhs, const path& rhs) noexcept;
  bool operator< (const path& lhs, const path& rhs) noexcept;
  bool operator<=(const path& lhs, const path& rhs) noexcept;
  bool operator> (const path& lhs, const path& rhs) noexcept;
  bool operator>=(const path& lhs, const path& rhs) noexcept;
  path operator/ (const path& lhs, const path& rhs);
  // path inserter and extractor
  template <class charT, class traits>
  basic_ostream<charT, traits>&
    operator<<(basic_ostream<charT, traits>& os, const path& p);
  template <class charT, class traits>
  basic_istream<charT, traits>&
    operator>>(basic_istream<charT, traits>& is, path& p);
  // path factory functions
  template <class Source>
  path u8path(const Source& source);
  template <class InputIterator>
  path u8path(InputIterator first, InputIterator last);
  // filesystem errors
  class filesystem_error;
  // directory entries
  class directory_entry;
  // directory iterators
  class directory_iterator;
  // range access for directory iterators
  directory_iterator begin(directory_iterator iter) noexcept;
  directory_iterator end(const directory_iterator&) noexcept;
  // recursive directory iterators
  class recursive_directory_iterator;
  // range access for recursive directory iterators
  recursive_directory_iterator begin(recursive_directory_iterator iter) noexcept;
  recursive_directory_iterator end(const recursive_directory_iterator&) noexcept;
  // file status
  class file_status;
  struct space_info {
    uintmax_t capacity;
    uintmax_t free;
    uintmax_t available;
  };
  // enumerations
  enum class file_type;
  enum class perms;
  enum class copy_options;
  enum class directory_options;
  using file_time_type = chrono::time_point<trivial-clock >;
  // filesystem operations
  path absolute(const path& p, const path& base = current_path());
  path canonical(const path& p, const path& base = current_path());
  path canonical(const path& p, error_code& ec);
  path canonical(const path& p, const path& base, error_code& ec);
  void copy(const path& from, const path& to);
  void copy(const path& from, const path& to, error_code& ec) noexcept;
  void copy(const path& from, const path& to, copy_options options);
  void copy(const path& from, const path& to, copy_options options,
            error_code& ec) noexcept;
  bool copy_file(const path& from, const path& to);
  bool copy_file(const path& from, const path& to, error_code& ec) noexcept;
  bool copy_file(const path& from, const path& to, copy_options option);
  bool copy_file(const path& from, const path& to, copy_options option,
                 error_code& ec) noexcept;
  void copy_symlink(const path& existing_symlink, const path& new_symlink);
  void copy_symlink(const path& existing_symlink, const path& new_symlink,
                    error_code& ec) noexcept;
  bool create_directories(const path& p);
  bool create_directories(const path& p, error_code& ec) noexcept;
  bool create_directory(const path& p);
  bool create_directory(const path& p, error_code& ec) noexcept;
  bool create_directory(const path& p, const path& attributes);
  bool create_directory(const path& p, const path& attributes,
                        error_code& ec) noexcept;
  void create_directory_symlink(const path& to, const path& new_symlink);
  void create_directory_symlink(const path& to, const path& new_symlink,
                                error_code& ec) noexcept;
  void create_hard_link(const path& to, const path& new_hard_link);
  void create_hard_link(const path& to, const path& new_hard_link,
                        error_code& ec) noexcept;
  void create_symlink(const path& to, const path& new_symlink);
  void create_symlink(const path& to, const path& new_symlink,
                      error_code& ec) noexcept;
  path current_path();
  path current_path(error_code& ec);
  void current_path(const path& p);
  void current_path(const path& p, error_code& ec) noexcept;
  bool exists(file_status s) noexcept;
  bool exists(const path& p);
  bool exists(const path& p, error_code& ec) noexcept;
  bool equivalent(const path& p1, const path& p2);
  bool equivalent(const path& p1, const path& p2, error_code& ec) noexcept;
  uintmax_t file_size(const path& p);
  uintmax_t file_size(const path& p, error_code& ec) noexcept;
  uintmax_t hard_link_count(const path& p);
  uintmax_t hard_link_count(const path& p, error_code& ec) noexcept;
  bool is_block_file(file_status s) noexcept;
  bool is_block_file(const path& p);
  bool is_block_file(const path& p, error_code& ec) noexcept;
  bool is_character_file(file_status s) noexcept;
  bool is_character_file(const path& p);
  bool is_character_file(const path& p, error_code& ec) noexcept;
  bool is_directory(file_status s) noexcept;
  bool is_directory(const path& p);
  bool is_directory(const path& p, error_code& ec) noexcept;
  bool is_empty(const path& p);
  bool is_empty(const path& p, error_code& ec) noexcept;
  bool is_fifo(file_status s) noexcept;
  bool is_fifo(const path& p);
  bool is_fifo(const path& p, error_code& ec) noexcept;
  bool is_other(file_status s) noexcept;
  bool is_other(const path& p);
  bool is_other(const path& p, error_code& ec) noexcept;
  bool is_regular_file(file_status s) noexcept;
  bool is_regular_file(const path& p);
  bool is_regular_file(const path& p, error_code& ec) noexcept;
  bool is_socket(file_status s) noexcept;
  bool is_socket(const path& p);
  bool is_socket(const path& p, error_code& ec) noexcept;
  bool is_symlink(file_status s) noexcept;
  bool is_symlink(const path& p);
  bool is_symlink(const path& p, error_code& ec) noexcept;
  file_time_type last_write_time(const path& p);
  file_time_type last_write_time(const path& p, error_code& ec) noexcept;
  void last_write_time(const path& p, file_time_type new_time);
  void last_write_time(const path& p, file_time_type new_time,
                       error_code& ec) noexcept;
  void permissions(const path& p, perms prms);
  void permissions(const path& p, perms prms, error_code& ec);
  path proximate(const path& p, error_code& ec);
  path proximate(const path& p, const path& base = current_path());
  path proximate(const path& p, const path& base, error_code& ec);
  path read_symlink(const path& p);
  path read_symlink(const path& p, error_code& ec);
  path relative(const path& p, error_code& ec);
  path relative(const path& p, const path& base = current_path());
  path relative(const path& p, const path& base, error_code& ec);
  bool remove(const path& p);
  bool remove(const path& p, error_code& ec) noexcept;
  uintmax_t remove_all(const path& p);
  uintmax_t remove_all(const path& p, error_code& ec) noexcept;
  void rename(const path& from, const path& to);
  void rename(const path& from, const path& to, error_code& ec) noexcept;
  void resize_file(const path& p, uintmax_t size);
  void resize_file(const path& p, uintmax_t size, error_code& ec) noexcept;
  space_info space(const path& p);
  space_info space(const path& p, error_code& ec) noexcept;
  file_status status(const path& p);
  file_status status(const path& p, error_code& ec) noexcept;
  bool status_known(file_status s) noexcept;
  file_status symlink_status(const path& p);
  file_status symlink_status(const path& p, error_code& ec) noexcept;
  path system_complete(const path& p);
  path system_complete(const path& p, error_code& ec);
  path temp_directory_path();
  path temp_directory_path(error_code& ec);
  path weakly_canonical(const path& p);
  path weakly_canonical(const path& p, error_code& ec);
}

Class std::filesystem::path

class path {
public:
  using value_type = /*see definition*/ ;
  using string_type = basic_string<value_type>;
  static constexpr value_type preferred_separator = /*see definition*/ ;
  // constructors and destructor
  path() noexcept;
  path(const path& p);
  path(path&& p) noexcept;
  path(string_type&& source);
  template <class Source>
  path(const Source& source);
  template <class InputIterator>
  path(InputIterator first, InputIterator last);
  template <class Source>
  path(const Source& source, const locale& loc);
  template <class InputIterator>
  path(InputIterator first, InputIterator last, const locale& loc);
  ~path();
  // 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);
  // 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);
  // 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);
  // modifiers
  void 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;
  // native format observers
  const 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 string() const;
  std::wstring wstring() const;
  std::string u8string() const;
  std::u16string u16string() const;
  std::u32string u32string() const;
  // generic format observers
  template <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_string() const;
  std::wstring generic_wstring() const;
  std::string generic_u8string() const;
  std::u16string generic_u16string() const;
  std::u32string generic_u32string() const;
  // compare
  int 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;
  // 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;
  // query
  bool 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;
  // generation
  path lexically_normal() const;
  path lexically_relative(const path& base) const;
  path lexically_proximate(const path& base) const;
  // iterators
  class iterator;
  using const_iterator = iterator;
  iterator begin() const;
  iterator end() const;
private:
  string_type pathstring; // exposition only
};

Class std::filesystem::filesystem_error

class filesystem_error : public system_error {
public:
  filesystem_error(const string& what_arg, error_code ec);
  filesystem_error(const string& what_arg,
                   const path& p1, error_code ec);
  filesystem_error(const string& what_arg,
                   const path& p1, const path& p2, error_code ec);
  const path& path1() const noexcept;
  const path& path2() const noexcept;
  const char* what() const noexcept override;
};

Class std::filesystem::file_status

class file_status {
public:
  // constructors and destructor
  explicit file_status(file_type ft = file_type::none,
                       perms prms = perms::unknown) noexcept;
  file_status(const file_status&) noexcept = default;
  file_status(file_status&&) noexcept = default;
  ~file_status();
  // assignments:
  file_status& operator=(const file_status&) noexcept = default;
  file_status& operator=(file_status&&) noexcept = default;
  // modifiers
  void type(file_type ft) noexcept;
  void permissions(perms prms) noexcept;
  // observers
  file_type type() const noexcept;
  perms permissions() const noexcept;
};

Class std::directory_entry

class directory_entry {
public:
  // constructors and destructor
  explicit directory_entry(const path& p);
  directory_entry() noexcept = default;
  directory_entry(const directory_entry&) = default;
  directory_entry(directory_entry&&) noexcept = default;
  ~directory_entry();
  // assignments:
  directory_entry& operator=(const directory_entry&) = default;
  directory_entry& operator=(directory_entry&&) noexcept = default;
  // modifiers
  void assign(const path& p);
  void replace_filename(const path& p);
  // observers
  const path& path() const noexcept;
  operator const path&() const noexcept;
  file_status status() const;
  file_status status(error_code& ec) const noexcept;
  file_status symlink_status() const;
  file_status symlink_status(error_code& ec) const noexcept;
  bool operator< (const directory_entry& rhs) const noexcept;
  bool operator==(const directory_entry& rhs) const noexcept;
  bool operator!=(const directory_entry& rhs) const noexcept;
  bool operator<=(const directory_entry& rhs) const noexcept;
  bool operator> (const directory_entry& rhs) const noexcept;
  bool operator>=(const directory_entry& rhs) const noexcept;
private:
  path pathobject; // exposition only
};

Class std::filesystem::directory_iterator

class directory_iterator {
public:
  using iterator_category = input_iterator_tag;
  using value_type = directory_entry;
  using difference_type = ptrdiff_t;
  using pointer = const directory_entry*;
  using reference = const directory_entry&;
  // member functions
  directory_iterator() noexcept;
  explicit directory_iterator(const path& p);
  directory_iterator(const path& p, directory_options options);
  directory_iterator(const path& p, error_code& ec) noexcept;
  directory_iterator(const path& p, directory_options options,
                     error_code& ec) noexcept;
  directory_iterator(const directory_iterator& rhs);
  directory_iterator(directory_iterator&& rhs) noexcept;
  ~directory_iterator();
  directory_iterator& operator=(const directory_iterator& rhs);
  directory_iterator& operator=(directory_iterator&& rhs) noexcept;
  const directory_entry& operator*() const;
  const directory_entry* operator->() const;
  directory_iterator& operator++();
  directory_iterator& increment(error_code& ec) noexcept;
  // other members as required by input iterators
};

Class std::filesystem::recursive_directory_iterator

class recursive_directory_iterator {
public:
  using iterator_category = input_iterator_tag;
  using value_type = directory_entry;
  using difference_type = ptrdiff_t;
  using pointer = const directory_entry*;
  using reference = const directory_entry&;
  // constructors and destructor
  recursive_directory_iterator() noexcept;
  explicit recursive_directory_iterator(const path& p);
  recursive_directory_iterator(const path& p, directory_options options);
  recursive_directory_iterator(const path& p, directory_options options,
                               error_code& ec) noexcept;
  recursive_directory_iterator(const path& p, error_code& ec) noexcept;
  recursive_directory_iterator(const recursive_directory_iterator& rhs);
  recursive_directory_iterator(recursive_directory_iterator&& rhs) noexcept;
  ~recursive_directory_iterator();
  // observers
  directory_options options() const;
  int depth() const;
  bool recursion_pending() const;
  const directory_entry& operator*() const;
  const directory_entry* operator->() const;
  // modifiers
  recursive_directory_iterator&
  operator=(const recursive_directory_iterator& rhs);
  recursive_directory_iterator&
  operator=(recursive_directory_iterator&& rhs) noexcept;
  recursive_directory_iterator& operator++();
  recursive_directory_iterator& increment(error_code& ec) noexcept;
  void pop();
  void pop(error_code& ec);
  void disable_recursion_pending();
  // other members as required by input iterators
};