Filesystem library

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Experimental

Technical Specification

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals TS v2)

Library fundamentals 3 (library fundamentals TS v3)

Extensions for parallelism (parallelism TS)

Extensions for parallelism 2 (parallelism TS v2)

Extensions for concurrency (concurrency TS)

Extensions for concurrency 2 (concurrency TS v2)

Concepts (concepts TS)

Ranges (ranges TS)

Reflection (reflection TS)

Mathematical special functions (special functions TR)

Experimental Non-TS

Pattern Matching

Linear Algebra

std::execution

Contracts

2D Graphics

 

Filesystem library

Classes
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator filesystem::file_status	filesystem::space_info filesystem::file_type filesystem::perms filesystem::copy_options filesystem::directory_options filesystem::file_time_type
Functions
filesystem::absolute filesystem::system_complete filesystem::canonical filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path filesystem::exists filesystem::equivalent	filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status filesystem::temp_directory_path
File types
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

 

The Filesystem library, ISO/IEC TS 18822:2015, provides facilities for performing operations on file systems and their components, such as paths, regular files, and directories.

This library is an optional technical specification and may be unavailable if a hierarchical file system is not accessible to the implementation, or if it does not provide the necessary capabilities. Some features may not be available if they are not supported by the underlying file system (e.g. FAT filesystem has no hardlinks, softlinks, and other features).

The behavior is undefined if the calls to functions in this library introduce a file system race, that is, when multiple threads, processes, or computers interleave access and modification to the same object in a file system.

This library is directly based on boost.filesystem, which is currently available on more compilers and platforms than this experimental technical specification.

Library-wide definitions

• file: a file system object that holds data, can be written to, read from, or both. Files have names, attributes, one of which is file type:

• directory: a file that acts as a container of directory entries, which identify other files (some of which may be other, nested, directories). When discussing a particular file, the directory in which it appears as an entry is its parent directory. The parent directory can be represented by the relative pathname "..".
• hard link: a directory entry that associates a name with an existing file. If multiple hard links are supported, the file is removed after the last hard link to it is removed.
• symbolic link: a directory entry that associates a name with a path, which may or may not exist.
• regular file: a file that is not one of the other file types.

• file name: a string of characters that names a file. Permissible characters, case sensitivity, maximum length, and the disallowed names are implementation-defined. Names . (dot) and .. (dot-dot) have special meaning at library level.
• path: sequence of elements that identifies a file. It begins with an optional root-name (e.g. "C:" or "//server"), followed by optional root-directory (e.g. "/" on Unix), followed by a sequence of zero or more file names (all but last of which have to be directories or links to directories). The native format (e.g. which characters are used as separators) and character encoding of the string representation of a path (the pathname) is implementation-defined, this library provides portable representation of paths.

• absolute path: a path that unambiguously identifies the location of a file.
• canonical path: an absolute path that includes no symlinks, "." or ".." elements.
• relative path: a path that identifies a file relative to some location on the file system. The special path names . (dot, "current directory") and .. (dot-dot, "parent directory") are relative paths.

Classes

path	represents a path (class)
filesystem_error	an exception thrown on file system errors (class)
directory_entry	a directory entry (class)
directory_iterator	an iterator to the contents of the directory (class)
recursive_directory_iterator	an iterator to the contents of a directory and its subdirectories (class)
file_status	represents file type and permissions (class)
space_info	information about free and available space on the filesystem (class)
file_type	the type of a file (enum)
perms	identifies file system permissions (enum)
copy_options	specifies semantics of copy operations (enum)
directory_options	options for iterating directory contents (enum)
file_time_type	represents file time values (typedef)

Non-member functions

absolutesystem_complete	composes an absolute path converts a path to an absolute path replicating OS-specific behavior (function)
canonical	composes a canonical path (function)
copy	copies files or directories (function)
copy_file	copies file contents (function)
copy_symlink	copies a symbolic link (function)
create_directorycreate_directories	creates new directory (function)
create_hard_link	creates a hard link (function)
create_symlinkcreate_directory_symlink	creates a symbolic link (function)
current_path	return current working directory (function)
exists	checks whether path refers to existing file system object (function)
equivalent	checks whether two paths refer to the same file system object (function)
file_size	returns the size of a file (function)
hard_link_count	returns the number of hard links referring to the specific file (function)
last_write_time	gets or sets the time of the last data modification (function)
permissions	modifies file access permissions (function)
read_symlink	obtains the target of a symbolic link (function)
removeremove_all	removes a file or empty directory removes a file or directory and all its contents, recursively (function)
rename	moves or renames a file or directory (function)
resize_file	changes the size of a regular file by truncation or zero-fill (function)
space	determines available free space on the file system (function)
statussymlink_status	determines file attributes determines file attributes, checking the symlink target (function)
temp_directory_path	returns a directory suitable for temporary files (function)
File types
is_block_file	checks whether the given path refers to block device (function)
is_character_file	checks whether the given path refers to a character device (function)
is_directory	checks whether the given path refers to a directory (function)
is_empty	checks whether the given path refers to an empty file or directory (function)
is_fifo	checks whether the given path refers to a named pipe (function)
is_other	checks whether the argument refers to an other file (function)
is_regular_file	checks whether the argument refers to a regular file (function)
is_socket	checks whether the argument refers to a named IPC socket (function)
is_symlink	checks whether the argument refers to a symbolic link (function)
status_known	checks whether file status is known (function)

See also

C++ documentation for Filesystem library (C++17)