operator==,!=,<,<=,>,>=,<=>(std::filesystem::path)

 

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)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

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::file_time_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options
Functions
filesystem::absolute filesystem::canonicalfilesystem::weakly_canonical filesystem::relativefilesystem::proximate 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::temp_directory_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
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

 

std::filesystem::path

Member types
Member constants
path::native_formatpath::generic_formatpath::auto_format
Member functions
path::path path::~path path::operator= path::assign path::appendpath::operator/= path::concatpath::operator+= path::clear path::make_preferred path::remove_filename path::replace_filename path::replace_extension    path::swap path::compare path::beginpath::end	path::c_strpath::nativepath::operator string_type path::stringpath::u8stringpath::u16stringpath::u32stringpath::wstring path::generic_stringpath::generic_u8stringpath::generic_u16stringpath::generic_u32stringpath::generic_wstring path::lexically_normalpath::lexically_relativepath::lexically_proximate
Path decomposition
path::root_name path::root_directory path::root_path path::relative_path path::parent_path path::filename path::stem path::extension path::empty	path::has_root_pathpath::has_root_namepath::has_root_directorypath::has_relative_pathpath::has_parent_pathpath::has_filenamepath::has_stempath::has_extension path::is_absolutepath::is_relative
Non-member functions
operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)	operator/ operator<<operator>> swap(std::filesystem::path) hash_value u8path
Helper classes
hash<std::filesystem::path>	formatter<std::filesystem::path> (C++26)

 

friendbool operator==(const path& lhs, const path& rhs )noexcept;	(1)	(since C++17)
friendbool operator!=(const path& lhs, const path& rhs )noexcept;	(2)	(since C++17) (until C++20)
friendbool operator<(const path& lhs, const path& rhs )noexcept;	(3)	(since C++17) (until C++20)
friendbool operator<=(const path& lhs, const path& rhs )noexcept;	(4)	(since C++17) (until C++20)
friendbool operator>(const path& lhs, const path& rhs )noexcept;	(5)	(since C++17) (until C++20)
friendbool operator>=(const path& lhs, const path& rhs )noexcept;	(6)	(since C++17) (until C++20)
friendstd::strong_ordering     operator<=>(const path& lhs, const path& rhs )noexcept;	(7)	(since C++20)

Compares two paths lexicographically.

1) Checks whether lhs and rhs are equal. Equivalent to !(lhs < rhs)&&!(rhs < lhs).

2) Checks whether lhs and rhs are not equal. Equivalent to !(lhs == rhs).

3) Checks whether lhs is less than rhs. Equivalent to lhs.compare(rhs)<0.

4) Checks whether lhs is less than or equal to rhs. Equivalent to !(rhs < lhs).

5) Checks whether lhs is greater than rhs. Equivalent to rhs < lhs.

6) Checks whether lhs is greater than or equal to rhs. Equivalent to !(lhs < rhs).

7) Obtains the three-way comparison result of lhs and rhs. Equivalent to lhs.compare(rhs)<=>0.

These functions are not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::filesystem::path is an associated class of the arguments. This prevents undesirable conversions in the presence of a usingnamespace std::filesystem;using-directive.

The <, <=, >, >=, and != operators are synthesized from operator<=> and operator== respectively.

(since C++20)

Parameters

lhs, rhs

-

the paths to compare

Return value

1-6)true if the corresponding comparison yields, false otherwise.

7)std::strong_ordering::less if lhs is less than rhs, otherwise std::strong_ordering::greater if rhs is less than lhs, otherwise std::strong_ordering::equal.

Notes

Path equality and equivalence have different semantics.

In the case of equality, as determined by operator==, only lexical representations are compared. Therefore, path("a")== path("b") is never true.

In the case of equivalence, as determined by std::filesystem::equivalent(), it is checked whether two paths resolve to the same file system object. Thus equivalent("a", "b") will return true if the paths resolve to the same file.

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 3065	C++17	allowed comparison of everything convertible to path in the presence of a using-directive	made hidden friend

See also

compare	compares the lexical representations of two paths lexicographically (public member function)
equivalent (C++17)	checks whether two paths refer to the same file system object (function)