std::unordered_multiset

 

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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 (C++23) unordered_multiset::emplace unordered_multiset::emplace_hint unordered_multiset::erase unordered_multiset::swap unordered_multiset::extract (C++17) unordered_multiset::merge (C++17)	Lookup unordered_multiset::count unordered_multiset::find unordered_multiset::contains (C++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!= (until C++20)	std::swap(std::unordered_multiset) erase_if(std::unordered_multiset) (C++20)
Deduction guides (C++17)

 

Defined in header <unordered_set>
template<     class Key,     class Hash = std::hash<Key>,     class KeyEqual = std::equal_to<Key>,     class Allocator = std::allocator<Key> > class unordered_multiset;	(1)	(since C++11)
namespace pmr {     template <class Key,               class Hash = std::hash<Key>,               class Pred = std::equal_to<Key>>     using unordered_multiset = std::unordered_multiset<Key, Hash, Pred,                                    std::pmr::polymorphic_allocator<Key>> }	(2)	(since C++17)

std::unordered_multiset es un contenedor asociativo que contiene un conjunto de objetos posiblemente no únicos de tipo Key. La búsqueda, inserción y eliminación tienen una complejidad promedio de tiempo constante.

Internamente, los elementos no se ordenan en ningún orden en particular, sino que se organizan en grupos. En qué depósito se coloca un elemento depende completamente de la dispersión (hash) de su valor. Esto permite un acceso rápido a elementos individuales, ya que una vez que se calcula la dispersión, se refiere al depósito exacto en el que se coloca el elemento.

No se requiere que el orden de iteración de este contenedor sea estable (así que, por ejemplo, std::equal no puede usarse para comparar dos std::unordered_multisets), excepto que cada grupo de elementos cuyas claves se comparan equivalentes (se comparan iguales con key_eq() como el comparador) forma un rango contiguo en el orden de iteración, también accesible con equal_range().

std::unordered_multiset cumple con los requerimientos de Container, AllocatorAwareContainer, UnorderedAssociativeContainer.

Tipos miembro

Tipo miembro	Definición
key_type	Key
value_type	Key
size_type	Unsigned integer type (usually std::size_t)
difference_type	Signed integer type (usually std::ptrdiff_t)
hasher	Hash
key_equal	KeyEqual
allocator_type	Allocator
reference	value_type&
const_reference	const value_type&
pointer	std::allocator_traits<Allocator>::pointer
const_pointer	std::allocator_traits<Allocator>::const_pointer
iterator	Constant LegacyForwardIterator to value_type
const_iterator	LegacyForwardIterator to const value_type
local_iterator	An iterator type whose category, value, difference, pointer and reference types are the same as iterator. This iterator can be used to iterate through a single bucket but not across buckets
const_local_iterator	An iterator type whose category, value, difference, pointer and reference types are the same as const_iterator. This iterator can be used to iterate through a single bucket but not across buckets
node_type (since C++17)	a specialization of node handle representing a container node

Funciones miembro

(constructor)	constructs the unordered_multiset (public member function)
(destructor)	destructs the unordered_multiset (public member function)
operator=	assigns values to the container (public member function)
get_allocator	returns the associated allocator (public member function)
Iteradores
begincbegin	returns an iterator to the beginning (public member function)
endcend	returns an iterator to the end (public member function)
Capacidad
empty	checks whether the container is empty (public member function)
size	returns the number of elements (public member function)
max_size	returns the maximum possible number of elements (public member function)
Modificadores
clear	clears the contents (public member function)
insert	inserts elements or nodes(since C++17) (public member function)
emplace	constructs element in-place (public member function)
emplace_hint	constructs elements in-place using a hint (public member function)
erase	erases elements (public member function)
swap	swaps the contents (public member function)
extract (C++17)	extracts nodes from the container (public member function)
merge (C++17)	splices nodes from another container (public member function)
Búsqueda
count	returns the number of elements matching specific key (public member function)
find	finds element with specific key (public member function)
contains (C++20)	checks if the container contains element with specific key (public member function)
equal_range	returns range of elements matching a specific key (public member function)
Interfaz de depósito
begin(size_type)cbegin(size_type)	returns an iterator to the beginning of the specified bucket (public member function)
end(size_type)cend(size_type)	returns an iterator to the end of the specified bucket (public member function)
bucket_count	returns the number of buckets (public member function)
max_bucket_count	returns the maximum number of buckets (public member function)
bucket_size	returns the number of elements in specific bucket (public member function)
bucket	returns the bucket for specific key (public member function)
Política de dispersión
load_factor	returns average number of elements per bucket (public member function)
max_load_factor	manages maximum average number of elements per bucket (public member function)
rehash	reserves at least the specified number of buckets and regenerates the hash table (public member function)
reserve	reserves space for at least the specified number of elements and regenerates the hash table (public member function)
Observadores
hash_function	returns function used to hash the keys (public member function)
key_eq	returns the function used to compare keys for equality (public member function)

Funciones no miembro

operator==operator!= (C++11)(C++11)(removed in C++20)	compares the values in the unordered_multiset (function template)
std::swap(std::unordered_multiset) (C++11)	specializes the std::swap algorithm (function template)
erase_if(std::unordered_multiset) (C++20)	erases all elements satisfying specific criteria (function template)

Notas

The member types iterator and const_iterator may be aliases to the same type. This means defining a pair of function overloads using the two types as parameter types may violate the One Definition Rule. Since iterator is convertible to const_iterator, a single function with a const_iterator as parameter type will work instead.