std::swap(std::unordered_multimap)

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Containers library

node-handle (C++17)

Sequence

array (C++11)

vector

vector<bool>

inplace_vector (C++26)

hive (C++26)

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Tables

Iterator invalidation

Member function table

Non-member function table

 

std::unordered_multimap

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

 

Defined in header <unordered_map>
template<class Key, class T, class Hash, class KeyEqual, class Alloc > void swap(std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& lhs,            std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& rhs );		(since C++11) (until C++17)
template<class Key, class T, class Hash, class KeyEqual, class Alloc > void swap(std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& lhs,            std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& rhs )                noexcept(/* see below */);		(since C++17)

Specializes the std::swap algorithm for std::unordered_multimap. Swaps the contents of lhs and rhs. Calls lhs.swap(rhs).

Parameters

lhs, rhs

-

containers whose contents to swap

Return value

(none)

Complexity

Constant.

Exceptions

noexcept specification:   noexcept(noexcept(lhs.swap(rhs)))

(since C++17)

Example

Run this code

#include <algorithm>#include <iostream>#include <unordered_map>   int main(){std::unordered_multimap<int, char> alice{{1, 'a'}, {2, 'b'}, {3, 'c'}};std::unordered_multimap<int, char> bob{{7, 'Z'}, {8, 'Y'}, {9, 'X'}, {10, 'W'}};   auto print =[](std::pair<constint, char>& n){std::cout<<' '<< n.first<<':'<< n.second;};   // Print state before swapstd::cout<<"Alice:";std::for_each(alice.begin(), alice.end(), print);std::cout<<"\nBobby:";std::for_each(bob.begin(), bob.end(), print);std::cout<<'\n';   std::cout<<"-- SWAP\n";std::swap(alice, bob);   // Print state after swapstd::cout<<"Alice:";std::for_each(alice.begin(), alice.end(), print);std::cout<<"\nBobby:";std::for_each(bob.begin(), bob.end(), print);std::cout<<'\n';}

Possible output:

Alice: 1:a 2:b 3:c Bobby: 7:Z 8:Y 9:X 10:W -- SWAP Alice: 7:Z 8:Y 9:X 10:W Bobby: 1:a 2:b 3:c

See also

swap	swaps the contents (public member function)