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

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< cpp‎ | filesystem‎ | path
 
C++
 
Filesystem library
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std::filesystem::path
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Path decomposition
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)
Helper classes
 
friend bool operator==( const path& lhs, const path& rhs ) noexcept;
 (1) (since C++17)
friend bool operator!=( const path& lhs, const path& rhs ) noexcept;
 (2) (since C++17)
(until C++20)
friend bool operator<( const path& lhs, const path& rhs ) noexcept;
 (3) (since C++17)
(until C++20)
friend bool operator<=( const path& lhs, const path& rhs ) noexcept;
 (4) (since C++17)
(until C++20)
friend bool operator>( const path& lhs, const path& rhs ) noexcept;
 (5) (since C++17)
(until C++20)
friend bool operator>=( const path& lhs, const path& rhs ) noexcept;
 (6) (since C++17)
(until C++20)
friend std::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 using namespace std::filesystem; using-directive.

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

(since C++20)

Contents

[edit] Parameters

lhs, rhs - the paths to compare

[edit] 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.

[edit] 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.

[edit] Example

This section is incomplete
Reason: no example

[edit] 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

[edit] See also

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