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

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

 

std::unordered_set

Member functions

unordered_set::unordered_set

unordered_set::~unordered_set

unordered_set::operator=

unordered_set::get_allocator

Iterators

unordered_set::beginunordered_set::cbegin

unordered_set::endunordered_set::cend

Capacity

unordered_set::erase

unordered_set::size

unordered_set::max_size

Modifiers

unordered_set::clear

unordered_set::insert

unordered_set::emplace

unordered_set::emplace_hint

unordered_set::erase

unordered_set::swap

Lookup

unordered_set::count

unordered_set::find

unordered_set::equal_range

Bucket interface

unordered_set::begin2

unordered_set::end2

unordered_set::bucket_count

unordered_set::max_bucket_count

unordered_set::bucket_size

unordered_set::bucket

Hash policy

unordered_set::load_factor

unordered_set::max_load_factor

unordered_set::rehash

unordered_set::reserve

Observers

unordered_set::hash_function

unordered_set::key_eq

 

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

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

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