# operator==,!=(std::unordered_map)

 template< class Key, class T, class Hash, class KeyEqual, class Allocator > bool operator==( const unordered_map& lhs,                  const unordered_map& rhs ); (1) template< class Key, class T, class Hash, class KeyEqual, class Allocator > bool operator!=( const unordered_map& lhs,                  const unordered_map& rhs ); (2)

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 elements [lhs_eq1, lhs_eq2) obtained from lhs.equal_range(lhs_eq1) has a corresponding group of equivalent elements in the other container [rhs_eq1, rhs_eq2) obtained from rhs.equal_range(rhs_eq1), that has the following properties:

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

The behavior is also undefined if hash_function() and key_eq() do (until C++20)key_eq() does (since C++20) not have the same behavior on lhs and rhs or if operator== for Key is not a refinement of the partition into equivalent-key groups introduced by key_eq() (that is, if two elements that compare equal using operator== fall into different partitions)

### Parameters

 lhs, rhs - unordered containers to compare

### 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

### Complexity

Proportional to N calls to operator== on value_type, calls to the predicate returned by key_eq, and calls to the hasher returned by hash_function, in the average case, proportional to N2 in the worst case where N is the size of the container.