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      operator==,!=(std::unordered_set)

      From cppreference.com
      <cpp‎ |container‎ |unordered set

      [edit template]
       
       
       
      std::unordered_set
      Member types
      Member functions
      Non-member functions
      operator==operator!=
      (until C++20)
      Deduction guides(C++17)
       
      template<class Key,class Hash,class KeyEqual,class Alloc>

      bool operator==(conststd::unordered_set<Key, Hash, KeyEqual, Alloc>& lhs,

                       conststd::unordered_set<Key, Hash, KeyEqual, Alloc>& rhs);
      (1)
      template<class Key,class Hash,class KeyEqual,class Alloc>

      bool operator!=(conststd::unordered_set<Key, Hash, KeyEqual, Alloc>& lhs,

                       conststd::unordered_set<Key, Hash, KeyEqual, Alloc>& rhs);
      (2)(until C++20)

      Compares the contents of two unordered containers.

      The contents of two unordered containerslhs andrhs are equal if the following conditions hold:

      • lhs.size()== rhs.size().
      • each group of equivalent elements[lhs_eq1lhs_eq2) obtained fromlhs.equal_range(lhs_eq1) has a corresponding group of equivalent elements in the other container[rhs_eq1rhs_eq2) obtained fromrhs.equal_range(rhs_eq1), that has the following properties:

      The behavior is undefined ifKey is notEqualityComparable.

      The behavior is also undefined ifhash_function() andkey_eq() do(until C++20)key_eq() does(since C++20) not have the same behavior onlhs andrhs or ifoperator== forKey is not a refinement of the partition into equivalent-key groups introduced bykey_eq() (that is, if two elements that compare equal usingoperator== fall into different partitions).

      The!= operator issynthesized fromoperator==.

      (since C++20)

      [edit]Parameters

      lhs, rhs - unordered containers to compare

      [edit]Return value

      1)true if the contents of the containers are equal,false otherwise.
      2)true if the contents of the containers are not equal,false otherwise.

      [edit]Complexity

      Proportional toN calls tooperator== onvalue_type, calls to the predicate returned bykey_eq, and calls to the hasher returned byhash_function, in the average case, proportional toN2 in the worst case whereN is the size of the container.

      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/container/unordered_set/operator_cmp&oldid=135987"

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