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Include the header <filesystem> for access to classes and functions that manipulate and retrieve information about paths, files and directories.
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Include the header <filesystem> for access to classes and functions that manipulate and retrieve information about paths, files, and directories.
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## Syntax
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```cpp
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#include<experimental/filesystem>// C++-standard header file name
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#include<filesystem>//Microsoft-specific implementation header file name
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#include<filesystem>// C++17 standard header file name
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#include<experimental/filesystem>//Header file for pre-standard implementation
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usingnamespacestd::experimental::filesystem::v1;
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```
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> [!IMPORTANT]
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> As of the release of Visual Studio 2017, the \<filesystem> header was not yet a C++ standard. C++ in Visual Studio 2017 (MSVC v141) implements the final draft standard, found in [ISO/IEC JTC 1/SC 22/WG 21 N4100](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4100.pdf).
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> At the release of Visual Studio 2017, the \<filesystem> header was not yet a C++ standard. C++ in Visual Studio 2017 RTW implements the final draft standard, found in [ISO/IEC JTC 1/SC 22/WG 21 N4100](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4100.pdf). Visual Studio 2017 version 15.7 and later supports the new C++17 \<filesystem> standard.
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> This is a completely new implementation, incompatible with the previous `std::experimental` version. It was made necessary by symlink support, bug fixes, and changes in standard-required behavior. Currently, including \<filesystem> provides the new `std::filesystem` and the previous `std::experimental::filesystem`. Including \<experimental/filesystem> provides only the old experimental implementation. The experimental implementation will be removed in the next ABI-breaking release of the libraries.
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This header supports filesystems for one of two broad classes of host operating systems: Microsoft Windows and POSIX.
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This header supports file systems for one of two broad classes of host operating systems: Microsoft Windows and POSIX.
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While most functionality is common to both operating systems, this document identifies where differences occur. For example:
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- Windows supports multiple root names, such as c: or \\\network_name. A filesystem consists of a forest of trees, each with its own root directory, such as c:\ or \\\network_name\\, and each with its own current directory, for completing a relative pathname (one that is not an absolute pathname).
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- Windows supports multiple root names, such as `c:` or `\\network_name`. A file system consists of a forest of trees, each with its own root directory, such as `c:\` or `\\network_name\`, and each with its own current directory, for completing a relative pathname (one that's not an absolute pathname).
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- POSIX supports a single tree, with no root name, the single root directory /, and a single current directory.
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- POSIX supports a single tree, with no root name, the single root directory `/`, and a single current directory.
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Another significant difference is the native representation of pathnames:
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- Windows uses a null-terminated sequence of wchar_t, encoded as UTF-16 (one or two elements for each character).
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- Windows uses a null-terminated sequence of **wchar_t**, encoded as UTF-16 (one or more elements for each character).
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- POSIX uses a null-terminated sequence of char, encoded as UTF-8 (one or more elements for each character).
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- POSIX uses a null-terminated sequence of **char**, encoded as UTF-8 (one or more elements for each character).
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- An object of class path stores the pathname in native form, but supports easy conversion between this stored form and several external forms:
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- An object of class `path` stores the pathname in native form, but supports easy conversion between this stored form and several external forms:
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- A null-terminated sequence of char, encoded as favored by the operating system.
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- A null-terminated sequence of **char**, encoded as favored by the operating system.
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- A null-terminated sequence of char, encoded as UTF-8.
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- A null-terminated sequence of **char**, encoded as UTF-8.
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- A null-terminated sequence of wchar_t, encoded as favored by the operating system.
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- A null-terminated sequence of **wchar_t**, encoded as favored by the operating system.
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- A null-terminated sequence of char16_t, encoded as UTF-16.
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- A null-terminated sequence of **char16_t**, encoded as UTF-16.
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- A null-terminated sequence of char32_t, encoded as UTF-32.
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- A null-terminated sequence of **char32_t**, encoded as UTF-32.
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Interconversions between these representations are mediated, as needed, by the use of one or more `codecvt` facets. If a specific locale object is not designated, these facets are obtained from the global locale.
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Interconversions between these representations are mediated, as needed, by the use of one or more `codecvt` facets. If no specific locale object is specified, these facets are obtained from the global locale.
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Another difference is the detail with which each operating system lets you specify file or directory access permissions:
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1. Windows records whether a file is readonly or writable, an attribute that has no meaning for directories.
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- Windows records whether a file is read-only or writable, an attribute that has no meaning for directories.
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1. POSIX records whether a file can be read, written, or executed (scanned if a directory), by the owner, by the owner's group, or by everybody, plus a few other permissions.
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- POSIX records whether a file can be read, written, or executed (scanned, if a directory). And, whether each operation is allowed for the owner, the owner's group, or for everybody, plus a few other permissions.
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Common to both systems is the structure imposed on a pathname once you get past the root name. For the pathname c:/abc/xyz/def.ext:
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Common to both systems is the structure imposed on a pathname once you get past the root name. For the pathname `c:/abc/xyz/def.ext`:
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- The root name is c:.
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- The root name is `c:`.
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- The root directory is /.
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- The root directory is `/`.
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- The root path is c:/.
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- The root path is `c:/`.
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- The relative path is abc/xyz/def.ext.
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- The relative path is `abc/xyz/def.ext`.
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- The parent path is c:/abc/xyz.
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- The parent path is `c:/abc/xyz`.
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- The filename is def.ext.
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- The filename is `def.ext`.
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- The stem is def.
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- The stem is `def`.
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- The extension is .ext.
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- The extension is `.ext`.
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A minor difference is the **preferred separator**, between the sequence of directories in a pathname. Both operating systems let you write a forward slash /, but in some contexts Windows prefers a backslash \\.
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A minor difference is the preferred separator between the sequence of directories in a pathname. Both operating systems let you write a forward slash `/`, but in some contexts Windows prefers a backslash `\`. The implementation stores its preferred separator in the data member `preferred_separator` in `path`.
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Finally, an important feature of path objects is that you can use them wherever a filename argument is required in the classes defined in the header \<fstream>.
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Finally, `path` objects have an important feature: You can use them wherever a filename argument is required in the classes defined in the header [\<fstream>](fstream.md).
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For more information and code examples, see [File System Navigation (C++)](../standard-library/file-system-navigation.md).
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For more information and code examples, see [File system navigation (C++)](../standard-library/file-system-navigation.md).
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## Members
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### Classes
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|[directory_entry Class](../standard-library/directory-entry-class.md)|Describes an object that is returned by a `directory_iterator` or a `recursive_directory_iterator` and contains a path.|
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|[directory_iterator Class](../standard-library/directory-iterator-class.md)|Describes an input iterator that sequences through the file names in a file-system directory.|
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|[filesystem_error Class](../standard-library/filesystem-error-class.md)|A base class for exceptions that are thrown to report a low-level system overflow.|
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|[path Class](../standard-library/path-class.md)|Defines a class that stores an object of template type `String` that is suitable for use as a file name.|
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|[recursive_directory_iterator Class](../standard-library/recursive-directory-iterator-class.md)|Describes an input iterator that sequences through the file names in a file-system directory. The iterator can also descend into subdirectories.|
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|[file_status Class](../standard-library/file-status-class.md)|Wraps a `file_type`.|
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|[directory_entry class](../standard-library/directory-entry-class.md)|Describes an object that is returned by a `directory_iterator` or a `recursive_directory_iterator` and contains a `path`.|
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|[directory_iterator class](../standard-library/directory-iterator-class.md)|Describes an input iterator that sequences through the file names in a file-system directory.|
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|[filesystem_error class](../standard-library/filesystem-error-class.md)|A base class for exceptions that are thrown to report a low-level system overflow.|
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|[path class](../standard-library/path-class.md)|Defines a class that stores an object of template type `String` that is suitable for use as a file name.|
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|[recursive_directory_iterator class](../standard-library/recursive-directory-iterator-class.md)|Describes an input iterator that sequences through the file names in a file-system directory. The iterator can also descend into subdirectories.|
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|[file_status class](../standard-library/file-status-class.md)|Wraps a `file_type`.|
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### Structs
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|[space_info Structure](../standard-library/space-info-structure.md)|Holds information about a volume.|
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|[space_info structure](../standard-library/space-info-structure.md)|Holds information about a volume.|
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## Functions
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@@ -109,12 +112,11 @@ For more information and code examples, see [File System Navigation (C++)](../st
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|[copy_options](../standard-library/filesystem-enumerations.md#copy_options)|An enumeration that is used with [copy_file](../standard-library/filesystem-functions.md#copy_file) and determines behavior if a destination file already exists.|
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|[copy_options](../standard-library/filesystem-enumerations.md#copy_options)|An enumeration that is used with [copy_file](../standard-library/filesystem-functions.md#copy_file) and determines behavior if a destination file already exists.|
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|[directory_options](../standard-library/filesystem-enumerations.md#directory_options)|An enumeration that specifies options for directory iterators.|
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|[file_type](../standard-library/filesystem-enumerations.md#file_type)|An enumeration for file types.|
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