operators (std::unordered_map)

template< class Key, class T, class Hash, class KeyEqual, class Allocator >
bool operator==( const unordered_map<Key,T,Hash,KeyEqual,Allocator>& lhs, 
                 const unordered_map<Key,T,Hash,KeyEqual,Allocator>& rhs );

template< class Key, class T, class Hash, class KeyEqual, class Allocator >
bool operator!=( const unordered_map<Key,T,Hash,KeyEqual,Allocator>& lhs, 
                 const unordered_map<Key,T,Hash,KeyEqual,Allocator>& rhs );

Compares the contents of two unordered containers.

The contents of two unordered containers lhs and rhs are equal if the following conditions hold:

• lhs.size() == rhs.size()
• each group of equivalent keys [lhs_eq1, lhs_eq2) obtained from lhs.equal_range(lhs_eq1) has a corresponding group of equivalent keys in the other container [rhs_eq1, rhs_eq2) obtained from rhs.equal_range(rhs_eq1), that has the following properties:
  • std::distance(lhs_eq1, lhs_eq2) == std::distance(rhs_eq1, rhs_eq2).
  • std::is_permutation(lhs_eq1, lhs_eq2, rhs_eq1) == true.

The behavior is undefined if Key or T are not EqualityComparable.

The behavior is also undefined if Hash and KeyEqual do not have the same behavior on lhs and rhs or if the equality comparison operator for Key is not a refinement of the partition into equivalent-key groups introduced by KeyEqual (that is, if two keys that compare equal fall into different partitions).

Parameters

Return value

Complexity

N comparisons of the keys in the average case, N² in the worst case, where N is the size of the container.