View source for cpp/filesystem/path/operator cmp

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{{title|1=operator==,!=,<,<=,>,>={{small|(std::filesystem::path)}}}}
{{cpp/filesystem/path/navbar}}
{{dcl begin}}
{{dcl | num=1 | since=c++17 | 1=
bool operator==( const path& lhs, const path& rhs ) noexcept;
}}
{{dcl | num=2 | since=c++17 | 1=
bool operator!=( const path& lhs, const path& rhs ) noexcept;
}}
{{dcl | num=3 | since=c++17 | 1=
bool operator<( const path& lhs, const path& rhs ) noexcept;
}}
{{dcl | num=4 | since=c++17 | 1=
bool operator<=( const path& lhs, const path& rhs ) noexcept;
}}
{{dcl | num=5 | since=c++17 | 1=
bool operator>( const path& lhs, const path& rhs ) noexcept;
}}
{{dcl | num=6 | since=c++17 | 1=
bool operator>=( const path& lhs, const path& rhs ) noexcept;
}}
{{dcl end}}

Compares two paths lexicographically.

@1@ Checks whether {{tt|lhs}} and {{tt|rhs}} are equal. Equivalent to {{c|!(lhs < rhs) && !(rhs < lhs)}}.

@2@ Checks whether {{tt|lhs}} and {{tt|rhs}} are not equal. Equivalent to {{c|!(lhs {{==}} rhs)}}.

@3@ Checks whether {{tt|lhs}} is less than {{tt|rhs}}. Equivalent to {{c|lhs.compare(rhs) < 0}}.

@4@ Checks whether {{tt|lhs}} is less than or equal to {{tt|rhs}}. Equivalent to {{c|!(rhs < lhs)}}.

@5@ Checks whether {{tt|lhs}} is greater than {{tt|rhs}}. Equivalent to {{c|rhs < lhs}}.

@6@ Checks whether {{tt|lhs}} is greater than or equal to {{tt|rhs}}. Equivalent to {{c|!(lhs < rhs)}}.

These functions are not visible to ordinary [[cpp/language/unqualified lookup|unqualified]] or [[cpp/language/qualified lookup|qualified lookup]] , and can only be found by [[cpp/language/adl|argument-dependent lookup]] when {{lc|std::filesystem::path}} is an associated class of the arguments. This prevents undesirable conversions in the presence of a {{c|using namespace std::filesystem;}} ''using-directive''.

===Parameters===
{{par begin}}
{{par | lhs, rhs | the paths to compare}}
{{par end}}

===Return value===
{{c|true}} if the corresponding comparison yields, {{c|false}} otherwise.

===Notes===
Path equality and equivalence have different semantics.

In the case of equality, as determined by {{tt|operator{{==}}}}, only lexical representations are compared. Therefore, {{c|1=path("a") == path("b")}} is never {{c|true}}.

In the case of equivalence, as determined by {{ltf|cpp/filesystem/equivalent}}, it is checked whether two paths ''resolve'' to the same file system object. Thus {{c|equivalent("a", "b")}} will return {{c|true}} if the paths resolve to the same file.

===Defect reports===
{{dr list begin}}
{{dr list item|dr=3065|wg=lwg|std=C++17|before=allowed comparison of everything convertible to {{tt|path}} in the presence of a ''using-directive''|after=made hidden friend}}
{{dr list end}}

===See also===
{{dsc begin}}
{{dsc inc | cpp/filesystem/path/dsc compare}}
{{dsc end}}

{{langlinks|ja|zh}}

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View source for cpp/filesystem/path/operator cmp