std::filesystem::path(3)

NAME
std::filesystem::path - std::filesystem::path

Synopsis
   Defined in header <filesystem>
   class path; (since C++17)
   Objects of type path represent paths on a filesystem. Only syntactic aspects of
   paths are handled: the pathname may represent a non-existing path or even one that
   is not allowed to exist on the current file system or OS.
   The path name has the following syntax:
    1. root-name(optional): identifies the root on a filesystem with multiple roots
       (such as "C:" or "//myserver"). In case of ambiguity, the longest sequence of
       characters that forms a valid root-name is treated as the root-name. The
       standard library may define additional root-names besides the ones understood by
       the OS API.
    2. root-directory(optional): a directory separator that, if present, marks this
       path as absolute. If it is missing (and the first element other than the root
       name is a file name), then the path is relative and requires another path as the
       starting location to resolve to a file name.
    3. Zero or more of the following:
     * file-name: sequence of characters that aren't directory separators or preferred
       directory separators (additional limitations may be imposed by the OS or file
       system). This name may identify a file, a hard link, a symbolic link, or a
       directory. Two special file-names are recognized:
     * dot: the file name consisting of a single dot character . is a directory name
       that refers to the current directory.
     * dot-dot: the file name consisting of two dot characters .. is a directory name
       that refers to the parent directory.
     * directory-separators: the forward slash character / or the alternative character
       provided as path::preferred_separator. If this character is repeated, it is
       treated as a single directory separator: /usr///////lib is the same as /usr/lib.
   A path can be normalized by following this algorithm:
    1. If the path is empty, stop (normal form of an empty path is an empty path).
    2. Replace each directory-separator (which may consist of multiple slashes) with a
       single path::preferred_separator.
    3. Replace each slash character in the root-name with path::preferred_separator.
    4. Remove each dot and any immediately following directory-separator.
    5. Remove each non-dot-dot filename immediately followed by a directory-separator
       and a dot-dot, along with any immediately following directory-separator.
    6. If there is root-directory, remove all dot-dots and any directory-separators
       immediately following them.
    7. If the last filename is dot-dot, remove any trailing directory-separator.
    8. If the path is empty, add a dot (normal form of ./ is .).
   The path can be traversed element-wise via iterators returned by the begin() and
   end() functions, which views the path in generic format and iterates over root name,
   root directory, and the subsequent file name elements (directory separators are
   skipped except the one that identifies the root directory). If the very last element
   in the path is a directory separator, the last iterator will dereference to an empty
   element.
   Calling any non-const member function of a path invalidates all iterators referring
   to elements of that object.
   If the OS uses a native syntax that is different from the portable generic syntax
   described above, library functions that are defined to accept "detected format"
   accept path names in both formats: a detected format argument is taken to be in the
   generic format if and only if it matches the generic format but is not acceptable to
   the operating system as a native path. On those OS where native format differs
   between pathnames of directories and pathnames of files, a generic pathname is
   treated as a directory path if it ends on a directory separator and a regular file
   otherwise.
   In any case, the path class behaves as if it stores a pathname in the native format
   and automatically converts to generic format as needed (each member function
   specifies which format it interprets the path as).
   On POSIX systems, the generic format is the native format and there is no need to
   distinguish or convert between them.
   Paths are implicitly convertible to and from std::basic_strings, which makes it
   possible to use them with other file APIs.
   The stream operators use std::quoted so that spaces do not cause truncation when
   later read by stream input operator.
   Decomposition member functions (e.g. extension) return filesystem::path objects
   instead of string objects as other APIs do.

Member types and constants
   Type Definition
   value_type character type used by the native encoding of the filesystem: char on
                  POSIX, wchar_t on Windows
   string_type std::basic_string<value_type>
                  a constant LegacyInputIterator with a value_type of path that meets
                  all requirements of LegacyBidirectionalIterator except that for two
                  equal dereferenceable iterators a and b of type const_iterator, there
   const_iterator is no requirement that *a and *b refer to the same object.
                  It is unspecified whether const_iterator is actually a
                  LegacyBidirectionalIterator
   iterator an alias to const_iterator
                  determines how to interpret string representations of pathnames.
                  The following enumerators are also defined:
   format Constant Explanation
   (C++17) native_format native pathname format
                  generic_format generic pathname format
                  auto_format implementation-defined format, auto-detected where
                        possible
                  (enum)

Member constants
                        alternative directory separator which may be used in addition
   constexpr value_type to the portable /. On Windows, this is the backslash character
   preferred_separator \. On POSIX, this is the same forward slash / as the portable
   [static] separator
                        (public static member constant)

Member functions
   constructor constructs a path
                        (public member function)
   destructor destroys a path object
                        (public member function)
   operator= assigns another path
                        (public member function)
   assign assigns contents
                        (public member function)
         Concatenation
   append appends elements to the path with a directory separator
   operator/= (public member function)
   concat concatenates two paths without introducing a directory
   operator+= separator
                        (public member function)

Modifiers
   clear erases the contents
                        (public member function)
   make_preferred converts directory separators to preferred directory separator
                        (public member function)
   remove_filename removes filename path component
                        (public member function)
   replace_filename replaces the last path component with another path
                        (public member function)
   replace_extension replaces the extension
                        (public member function)
   swap swaps two paths
                        (public member function)
         Format observers
   c_str returns the native version of the path
   native (public member function)
   operator string_type
   string
   wstring returns the path in native pathname format converted to a
   u8string string
   u16string (public member function)
   u32string
   generic_string
   generic_wstring returns the path in generic pathname format converted to a
   generic_u8string string
   generic_u16string (public member function)
   generic_u32string
         Compare
                        compares the lexical representations of two paths
   compare lexicographically
                        (public member function)

Generation
   lexically_normal converts path to normal form
   lexically_relative converts path to relative form
   lexically_proximate converts path to proximate form
                        (public member function)
         Decomposition
   root_name returns the root-name of the path, if present
                        (public member function)
   root_directory returns the root directory of the path, if present
                        (public member function)
   root_path returns the root path of the path, if present
                        (public member function)
   relative_path returns path relative to the root path
                        (public member function)
   parent_path returns the path of the parent path
                        (public member function)
   filename returns the filename path component
                        (public member function)
                        returns the stem path component (filename without the final
   stem extension)
                        (public member function)
   extension returns the file extension path component
                        (public member function)
         Queries
   empty checks if the path is empty
                        (public member function)
   has_root_path
   has_root_name
   has_root_directory
   has_relative_path checks if the corresponding path element is not empty
   has_parent_path (public member function)
   has_filename
   has_stem
   has_extension
   is_absolute checks if root_path() uniquely identifies file system location
   is_relative (public member function)

Iterators
   begin iterator access to the path as a sequence of elements
   end (public member function)

Non-member functions
   Defined in namespace std::filesystem
   swap(std::filesystem::path) swaps two paths
   (C++17) (function)
   hash_value calculates a hash value for a path object
   (C++17) (function)
   operator==
   operator!=
   operator<
   operator<=
   operator>
   operator>=
   operator<=> lexicographically compares two paths
   (C++17) (function)
   (C++17)(until C++20)
   (C++17)(until C++20)
   (C++17)(until C++20)
   (C++17)(until C++20)
   (C++17)(until C++20)
   (C++20)
   operator/ concatenates two paths with a directory separator
   (C++17) (function)
   operator<< performs stream input and output on a quoted path
   operator>> (function)
   (C++17)
   u8path creates a path from a UTF-8 encoded source
   (C++17)(deprecated in C++20) (function)

Helper classes
   Defined in namespace std
   std::hash<std::filesystem::path> hash support for std::filesystem::path
   (C++17) (class template specialization)
   std::formatter<std::filesystem::path> formatting support for filesystem::path
   (C++26) (class template specialization)
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
   LWG 3657 C++17 hash for path was disabled enabled