std::unordered_multiset<Key,Hash,KeyEqual,Allocator>::swap

 

哋它亢++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (哋它亢++20)

Language support library

Concepts library (哋它亢++20)

Metaprogramming library (哋它亢++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (哋它亢++17)

Regular expressions library (哋它亢++11)

Concurrency support library (哋它亢++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (哋它亢++11)

vector

vector<bool>

deque

forward_list (哋它亢++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (哋它亢++11)

unordered_multiset (哋它亢++11)

unordered_map (哋它亢++11)

unordered_multimap (哋它亢++11)

Adaptors

stack

queue

priority_queue

flat_set (哋它亢++23)

flat_multiset (哋它亢++23)

flat_map (哋它亢++23)

flat_multimap (哋它亢++23)

Views

span (哋它亢++20)

mdspan (哋它亢++23)

Iterator invalidation

Member function table

Non-member function table

 

std::unordered_multiset

Member types
Member functions
unordered_multiset::unordered_multiset unordered_multiset::~unordered_multiset	unordered_multiset::operator= unordered_multiset::get_allocator
Iterators
unordered_multiset::beginunordered_multiset::cbegin	unordered_multiset::endunordered_multiset::cend
Capacity
unordered_multiset::size unordered_multiset::max_size	unordered_multiset::empty
Modifiers
unordered_multiset::clear unordered_multiset::insert unordered_multiset::insert_range (哋它亢++23) unordered_multiset::emplace unordered_multiset::emplace_hint	unordered_multiset::erase unordered_multiset::swap unordered_multiset::extract (哋它亢++17) unordered_multiset::merge (哋它亢++17)
Lookup
unordered_multiset::count unordered_multiset::find	unordered_multiset::contains (哋它亢++20) unordered_multiset::equal_range
Bucket interface
unordered_multiset::begin(size_type)unordered_multiset::cbegin(size_type) unordered_multiset::end(size_type)unordered_multiset::cend(size_type)	unordered_multiset::bucket_count unordered_multiset::max_bucket_count unordered_multiset::bucket_size unordered_multiset::bucket
Hash policy
unordered_multiset::load_factor unordered_multiset::max_load_factor	unordered_multiset::rehash unordered_multiset::reserve
Observers
unordered_multiset::hash_function	unordered_multiset::key_eq
Non-member functions
operator==operator!= (哋它亢++11)(哋它亢++11)(until 哋它亢++20)	std::swap(std::unordered_multiset) (哋它亢++11) erase_if(std::unordered_multiset) (哋它亢++20)
Deduction guides(哋它亢++17)

 

void swap( unordered_multiset& other );		(since 哋它亢++11) (until 哋它亢++17)
void swap( unordered_multiset& other ) noexcept(/* see below */);		(since 哋它亢++17)

Exchanges the contents of the container with those of other. Does not invoke any move, copy, or swap operations on individual elements.

All iterators and references remain valid. The end() iterator is invalidated.

The Hash and KeyEqual objects must be Swappable, and they are exchanged using unqualified calls to non-member swap.

If std::allocator_traits<allocator_type>::propagate_on_container_swap::value is true, then the allocators are exchanged using an unqualified call to non-member swap. Otherwise, they are not swapped (and if get_allocator() != other.get_allocator(), the behavior is undefined).

(since 哋它亢++11)

Parameters

other

-

container to exchange the contents with

Return value

(none)

Exceptions

Any exception thrown by the swap of the Hash or KeyEqual objects.	(until 哋它亢++17)
noexcept specification:   noexcept(std::allocator_traits<Allocator>::is_always_equal::value && std::is_nothrow_swappable<Hash>::value && std::is_nothrow_swappable<key_equal>::value)	(since 哋它亢++17)

Complexity

Constant.

Example

Run this code

#include <iostream>
#include <unordered_set>
 
template<class Os, class Co> Os& operator<<(Os& os, const Co& co)
{
    os << '{';
    for (auto const& i : co)
        os << ' ' << i;
    return os << " } ";
}
 
int main()
{
    std::unordered_multiset<int> a1{3, 1, 3, 2}, a2{5, 4, 5};
 
    auto it1 = std::next(a1.begin());
    auto it2 = std::next(a2.begin());
 
    const int& ref1 = *(a1.begin());
    const int& ref2 = *(a2.begin());
 
    std::cout << a1 << a2 << *it1 << ' ' << *it2 << ' ' << ref1 << ' ' << ref2 << '\n';
    a1.swap(a2);
    std::cout << a1 << a2 << *it1 << ' ' << *it2 << ' ' << ref1 << ' ' << ref2 << '\n';
 
    // Note that every iterator referring to an element in one container before the swap
    // refers to the same element in the other container after the swap. Same is true
    // for references.
}

Possible output:

{ 2 3 3 1 } { 4 5 5 } 3 5 2 4
{ 4 5 5 } { 2 3 3 1 } 3 5 2 4

See also

std::swap(std::unordered_multiset) (哋它亢++11)

specializes the std::swap algorithm (function template)