The header <unordered_map> defines the class templates unordered_map and unordered_multimap; the header <unordered_set> defines the class templates unordered_set and unordered_multiset.
23.5.2 Header <unordered_map> synopsis [unord.map.syn]#include <initializer_list>
namespace std {
template <class Key,
class T,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Alloc = std::allocator<std::pair<const Key, T> > >
class unordered_map;
template <class Key,
class T,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Alloc = std::allocator<std::pair<const Key, T> > >
class unordered_multimap;
template <class Key, class T, class Hash, class Pred, class Alloc>
void swap(unordered_map<Key, T, Hash, Pred, Alloc>& x,
unordered_map<Key, T, Hash, Pred, Alloc>& y);
template <class Key, class T, class Hash, class Pred, class Alloc>
void swap(unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
unordered_multimap<Key, T, Hash, Pred, Alloc>& y);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator==(const unordered_map<Key, T, Hash, Pred, Alloc>& a,
const unordered_map<Key, T, Hash, Pred, Alloc>& b);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_map<Key, T, Hash, Pred, Alloc>& a,
const unordered_map<Key, T, Hash, Pred, Alloc>& b);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator==(const unordered_multimap<Key, T, Hash, Pred, Alloc>& a,
const unordered_multimap<Key, T, Hash, Pred, Alloc>& b);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_multimap<Key, T, Hash, Pred, Alloc>& a,
const unordered_multimap<Key, T, Hash, Pred, Alloc>& b);
} 23.5.3 Header <unordered_set> synopsis [unord.set.syn]
#include <initializer_list>
namespace std {
template <class Key,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Alloc = std::allocator<Key> >
class unordered_set;
template <class Key,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Alloc = std::allocator<Key> >
class unordered_multiset;
template <class Key, class Hash, class Pred, class Alloc>
void swap(unordered_set<Key, Hash, Pred, Alloc>& x,
unordered_set<Key, Hash, Pred, Alloc>& y);
template <class Key, class Hash, class Pred, class Alloc>
void swap(unordered_multiset<Key, Hash, Pred, Alloc>& x,
unordered_multiset<Key, Hash, Pred, Alloc>& y);
template <class Key, class Hash, class Pred, class Alloc>
bool operator==(const unordered_set<Key, Hash, Pred, Alloc>& a,
const unordered_set<Key, Hash, Pred, Alloc>& b);
template <class Key, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_set<Key, Hash, Pred, Alloc>& a,
const unordered_set<Key, Hash, Pred, Alloc>& b);
template <class Key, class Hash, class Pred, class Alloc>
bool operator==(const unordered_multiset<Key, Hash, Pred, Alloc>& a,
const unordered_multiset<Key, Hash, Pred, Alloc>& b);
template <class Key, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_multiset<Key, Hash, Pred, Alloc>& a,
const unordered_multiset<Key, Hash, Pred, Alloc>& b);
} 23.5.4 Class template unordered_map [unord.map] 23.5.4.1 Class template unordered_map overview [unord.map.overview]
An unordered_map is an unordered associative container that supports unique keys (an unordered_map contains at most one of each key value) and that associates values of another type mapped_type with the keys. The unordered_map class supports forward iterators.
An unordered_map satisfies all of the requirements of a container, of an unordered associative container, and of an allocator-aware container (Table [tab:containers.allocatoraware]). It provides the operations described in the preceding requirements table for unique keys; that is, an unordered_map supports the a_uniq operations in that table, not the a_eq operations. For an unordered_map<Key, T> the key type is Key, the mapped type is T, and the value type is std::pair<const Key, T>.
This section only describes operations on unordered_map that are not described in one of the requirement tables, or for which there is additional semantic information.
namespace std {
template <class Key,
class T,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Allocator = std::allocator<std::pair<const Key, T> > >
class unordered_map
{
public:
typedef Key key_type;
typedef std::pair<const Key, T> value_type;
typedef T mapped_type;
typedef Hash hasher;
typedef Pred key_equal;
typedef Allocator allocator_type;
typedef typename allocator_traits<Allocator>::pointer pointer;
typedef typename allocator_traits<Allocator>::const_pointer const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef implementation-defined size_type;
typedef implementation-defined difference_type;
typedef implementation-defined iterator;
typedef implementation-defined const_iterator;
typedef implementation-defined local_iterator;
typedef implementation-defined const_local_iterator;
unordered_map();
explicit unordered_map(size_type n,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template <class InputIterator>
unordered_map(InputIterator f, InputIterator l,
size_type n = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_map(const unordered_map&);
unordered_map(unordered_map&&);
explicit unordered_map(const Allocator&);
unordered_map(const unordered_map&, const Allocator&);
unordered_map(unordered_map&&, const Allocator&);
unordered_map(initializer_list<value_type>,
size_type = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_map(size_type n, const allocator_type& a)
: unordered_map(n, hasher(), key_equal(), a) { }
unordered_map(size_type n, const hasher& hf, const allocator_type& a)
: unordered_map(n, hf, key_equal(), a) { }
template <class InputIterator>
unordered_map(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
: unordered_map(f, l, n, hasher(), key_equal(), a) { }
template <class InputIterator>
unordered_map(InputIterator f, InputIterator l, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_map(f, l, n, hf, key_equal(), a) { }
unordered_map(initializer_list<value_type> il, size_type n, const allocator_type& a)
: unordered_map(il, n, hasher(), key_equal(), a) { }
unordered_map(initializer_list<value_type> il, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_map(il, n, hf, key_equal(), a) { }
~unordered_map();
unordered_map& operator=(const unordered_map&);
unordered_map& operator=(unordered_map&&);
unordered_map& operator=(initializer_list<value_type>);
allocator_type get_allocator() const noexcept;
bool empty() const noexcept;
size_type size() const noexcept;
size_type max_size() const noexcept;
iterator begin() noexcept;
const_iterator begin() const noexcept;
iterator end() noexcept;
const_iterator end() const noexcept;
const_iterator cbegin() const noexcept;
const_iterator cend() const noexcept;
template <class... Args> pair<iterator, bool> emplace(Args&&... args);
template <class... Args> iterator emplace_hint(const_iterator position, Args&&... args);
pair<iterator, bool> insert(const value_type& obj);
template <class P> pair<iterator, bool> insert(P&& obj);
iterator insert(const_iterator hint, const value_type& obj);
template <class P> iterator insert(const_iterator hint, P&& obj);
template <class InputIterator> void insert(InputIterator first, InputIterator last);
void insert(initializer_list<value_type>);
iterator erase(const_iterator position);
size_type erase(const key_type& k);
iterator erase(const_iterator first, const_iterator last);
void clear() noexcept;
void swap(unordered_map&);
hasher hash_function() const;
key_equal key_eq() const;
iterator find(const key_type& k);
const_iterator find(const key_type& k) const;
size_type count(const key_type& k) const;
std::pair<iterator, iterator> equal_range(const key_type& k);
std::pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
mapped_type& operator[](const key_type& k);
mapped_type& operator[](key_type&& k);
mapped_type& at(const key_type& k);
const mapped_type& at(const key_type& k) const;
size_type bucket_count() const noexcept;
size_type max_bucket_count() const noexcept;
size_type bucket_size(size_type n) const;
size_type bucket(const key_type& k) const;
local_iterator begin(size_type n);
const_local_iterator begin(size_type n) const;
local_iterator end(size_type n);
const_local_iterator end(size_type n) const;
const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
float load_factor() const noexcept;
float max_load_factor() const noexcept;
void max_load_factor(float z);
void rehash(size_type n);
void reserve(size_type n);
};
template <class Key, class T, class Hash, class Pred, class Alloc>
void swap(unordered_map<Key, T, Hash, Pred, Alloc>& x,
unordered_map<Key, T, Hash, Pred, Alloc>& y);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator==(const unordered_map<Key, T, Hash, Pred, Alloc>& a,
const unordered_map<Key, T, Hash, Pred, Alloc>& b);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_map<Key, T, Hash, Pred, Alloc>& a,
const unordered_map<Key, T, Hash, Pred, Alloc>& b);
}
23.5.4.2 unordered_map constructors [unord.map.cnstr]
unordered_map() : unordered_map(size_type(see below)) { } explicit unordered_map(size_type n, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_map using the specified hash function, key equality function, and allocator, and using at least n buckets. For the default constructor, the number of buckets is implementation-defined. max_load_factor() returns 1.0.
template <class InputIterator> unordered_map(InputIterator f, InputIterator l, size_type n = see below, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_map using the specified hash function, key equality function, and allocator, and using at least n buckets. If n is not provided, the number of buckets is implementation-defined. Then inserts elements from the range [f, l). max_load_factor() returns 1.0.
Complexity: Average case linear, worst case quadratic.
23.5.4.3 unordered_map element access [unord.map.elem] mapped_type& operator[](const key_type& k); mapped_type& operator[](key_type&& k);
Requires: mapped_type shall be DefaultInsertable into *this. For the first operator, key_type shall be CopyInsertable into *this. For the second operator, key_type shall be MoveConstructible.
Effects: If the unordered_map does not already contain an element whose key is equivalent to k, the first operator inserts the value value_type(k, mapped_type()) and the second operator inserts the value value_type(std::move(k), mapped_type()).
Returns: A reference to x.second, where x is the (unique) element whose key is equivalent to k.
Complexity: Average case Ο(1), worst case Ο(size()).
mapped_type& at(const key_type& k); const mapped_type& at(const key_type& k) const;
Returns: A reference to x.second, where x is the (unique) element whose key is equivalent to k.
Throws: An exception object of type out_of_range if no such element is present.
23.5.4.4 unordered_map modifiers [unord.map.modifiers] template <class P> pair<iterator, bool> insert(P&& obj);
Effects: Equivalent to return emplace(std::forward<P>(obj)).
Remarks: This signature shall not participate in overload resolution unless std::is_constructible<value_type, P&&>::value is true.
template <class P> iterator insert(const_iterator hint, P&& obj);
Effects: Equivalent to return emplace_hint(hint, std::forward<P>(obj)).
Remarks: This signature shall not participate in overload resolution unless std::is_constructible<value_type, P&&>::value is true.
23.5.4.5 unordered_map swap [unord.map.swap] template <class Key, class T, class Hash, class Pred, class Alloc> void swap(unordered_map<Key, T, Hash, Pred, Alloc>& x, unordered_map<Key, T, Hash, Pred, Alloc>& y);
An unordered_multimap is an unordered associative container that supports equivalent keys (an instance of unordered_multimap may contain multiple copies of each key value) and that associates values of another type mapped_type with the keys. The unordered_multimap class supports forward iterators.
An unordered_multimap satisfies all of the requirements of a container, of an unordered associative container, and of an allocator-aware container (Table [tab:containers.allocatoraware]). It provides the operations described in the preceding requirements table for equivalent keys; that is, an unordered_multimap supports the a_eq operations in that table, not the a_uniq operations. For an unordered_multimap<Key, T> the key type is Key, the mapped type is T, and the value type is std::pair<const Key, T>.
This section only describes operations on unordered_multimap that are not described in one of the requirement tables, or for which there is additional semantic information.
namespace std {
template <class Key,
class T,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Allocator = std::allocator<std::pair<const Key, T> > >
class unordered_multimap
{
public:
typedef Key key_type;
typedef std::pair<const Key, T> value_type;
typedef T mapped_type;
typedef Hash hasher;
typedef Pred key_equal;
typedef Allocator allocator_type;
typedef typename allocator_traits<Allocator>::pointer pointer;
typedef typename allocator_traits<Allocator>::const_pointer const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef implementation-defined size_type;
typedef implementation-defined difference_type;
typedef implementation-defined iterator;
typedef implementation-defined const_iterator;
typedef implementation-defined local_iterator;
typedef implementation-defined const_local_iterator;
unordered_multimap();
explicit unordered_multimap(size_type n,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template <class InputIterator>
unordered_multimap(InputIterator f, InputIterator l,
size_type n = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_multimap(const unordered_multimap&);
unordered_multimap(unordered_multimap&&);
explicit unordered_multimap(const Allocator&);
unordered_multimap(const unordered_multimap&, const Allocator&);
unordered_multimap(unordered_multimap&&, const Allocator&);
unordered_multimap(initializer_list<value_type>,
size_type = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_multimap(size_type n, const allocator_type& a)
: unordered_multimap(n, hasher(), key_equal(), a) { }
unordered_multimap(size_type n, const hasher& hf, const allocator_type& a)
: unordered_multimap(n, hf, key_equal(), a) { }
template <class InputIterator>
unordered_multimap(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
: unordered_multimap(f, l, n, hasher(), key_equal(), a) { }
template <class InputIterator>
unordered_multimap(InputIterator f, InputIterator l, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_multimap(f, l, n, hf, key_equal(), a) { }
unordered_multimap(initializer_list<value_type> il, size_type n, const allocator_type& a)
: unordered_multimap(il, n, hasher(), key_equal(), a) { }
unordered_multimap(initializer_list<value_type> il, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_multimap(il, n, hf, key_equal(), a) { }
~unordered_multimap();
unordered_multimap& operator=(const unordered_multimap&);
unordered_multimap& operator=(unordered_multimap&&);
unordered_multimap& operator=(initializer_list<value_type>);
allocator_type get_allocator() const noexcept;
bool empty() const noexcept;
size_type size() const noexcept;
size_type max_size() const noexcept;
iterator begin() noexcept;
const_iterator begin() const noexcept;
iterator end() noexcept;
const_iterator end() const noexcept;
const_iterator cbegin() const noexcept;
const_iterator cend() const noexcept;
template <class... Args> iterator emplace(Args&&... args);
template <class... Args> iterator emplace_hint(const_iterator position, Args&&... args);
iterator insert(const value_type& obj);
template <class P> iterator insert(P&& obj);
iterator insert(const_iterator hint, const value_type& obj);
template <class P> iterator insert(const_iterator hint, P&& obj);
template <class InputIterator> void insert(InputIterator first, InputIterator last);
void insert(initializer_list<value_type>);
iterator erase(const_iterator position);
size_type erase(const key_type& k);
iterator erase(const_iterator first, const_iterator last);
void clear() noexcept;
void swap(unordered_multimap&);
hasher hash_function() const;
key_equal key_eq() const;
iterator find(const key_type& k);
const_iterator find(const key_type& k) const;
size_type count(const key_type& k) const;
std::pair<iterator, iterator> equal_range(const key_type& k);
std::pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
size_type bucket_count() const noexcept;
size_type max_bucket_count() const noexcept;
size_type bucket_size(size_type n) const;
size_type bucket(const key_type& k) const;
local_iterator begin(size_type n);
const_local_iterator begin(size_type n) const;
local_iterator end(size_type n);
const_local_iterator end(size_type n) const;
const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
float load_factor() const noexcept;
float max_load_factor() const noexcept;
void max_load_factor(float z);
void rehash(size_type n);
void reserve(size_type n);
};
template <class Key, class T, class Hash, class Pred, class Alloc>
void swap(unordered_multimap<Key, T, Hash, Pred, Alloc>& x,
unordered_multimap<Key, T, Hash, Pred, Alloc>& y);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator==(const unordered_multimap<Key, T, Hash, Pred, Alloc>& a,
const unordered_multimap<Key, T, Hash, Pred, Alloc>& b);
template <class Key, class T, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_multimap<Key, T, Hash, Pred, Alloc>& a,
const unordered_multimap<Key, T, Hash, Pred, Alloc>& b);
}
23.5.5.2 unordered_multimap constructors [unord.multimap.cnstr]
unordered_multimap() : unordered_multimap(size_type(see below)) { } explicit unordered_multimap(size_type n, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_multimap using the specified hash function, key equality function, and allocator, and using at least n buckets. For the default constructor, the number of buckets is implementation-defined. max_load_factor() returns 1.0.
template <class InputIterator> unordered_multimap(InputIterator f, InputIterator l, size_type n = see below, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_multimap using the specified hash function, key equality function, and allocator, and using at least n buckets. If n is not provided, the number of buckets is implementation-defined. Then inserts elements from the range [f, l). max_load_factor() returns 1.0.
Complexity: Average case linear, worst case quadratic.
23.5.5.3 unordered_multimap modifiers [unord.multimap.modifiers] template <class P> iterator insert(P&& obj);
Effects: Equivalent to return emplace(std::forward<P>(obj)).
Remarks: This signature shall not participate in overload resolution unless std::is_constructible<value_type, P&&>::value is true.
template <class P> iterator insert(const_iterator hint, P&& obj);
Effects: Equivalent to return emplace_hint(hint, std::forward<P>(obj)).
Remarks: This signature shall not participate in overload resolution unless std::is_constructible<value_type, P&&>::value is true.
23.5.5.4 unordered_multimap swap [unord.multimap.swap] template <class Key, class T, class Hash, class Pred, class Alloc> void swap(unordered_multimap<Key, T, Hash, Pred, Alloc>& x, unordered_multimap<Key, T, Hash, Pred, Alloc>& y);
An unordered_set is an unordered associative container that supports unique keys (an unordered_set contains at most one of each key value) and in which the elements' keys are the elements themselves. The unordered_set class supports forward iterators.
An unordered_set satisfies all of the requirements of a container, of an unordered associative container, and of an allocator-aware container (Table [tab:containers.allocatoraware]). It provides the operations described in the preceding requirements table for unique keys; that is, an unordered_set supports the a_uniq operations in that table, not the a_eq operations. For an unordered_set<Key> the key type and the value type are both Key. The iterator and const_iterator types are both const iterator types. It is unspecified whether they are the same type.
This section only describes operations on unordered_set that are not described in one of the requirement tables, or for which there is additional semantic information.
namespace std {
template <class Key,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Allocator = std::allocator<Key> >
class unordered_set
{
public:
typedef Key key_type;
typedef Key value_type;
typedef Hash hasher;
typedef Pred key_equal;
typedef Allocator allocator_type;
typedef typename allocator_traits<Allocator>::pointer pointer;
typedef typename allocator_traits<Allocator>::const_pointer const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef implementation-defined size_type;
typedef implementation-defined difference_type;
typedef implementation-defined iterator;
typedef implementation-defined const_iterator;
typedef implementation-defined local_iterator;
typedef implementation-defined const_local_iterator;
unordered_set();
explicit unordered_set(size_type n,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template <class InputIterator>
unordered_set(InputIterator f, InputIterator l,
size_type n = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_set(const unordered_set&);
unordered_set(unordered_set&&);
explicit unordered_set(const Allocator&);
unordered_set(const unordered_set&, const Allocator&);
unordered_set(unordered_set&&, const Allocator&);
unordered_set(initializer_list<value_type>,
size_type = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_set(size_type n, const allocator_type& a)
: unordered_set(n, hasher(), key_equal(), a) { }
unordered_set(size_type n, const hasher& hf, const allocator_type& a)
: unordered_set(n, hf, key_equal(), a) { }
template <class InputIterator>
unordered_set(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
: unordered_set(f, l, n, hasher(), key_equal(), a) { }
template <class InputIterator>
unordered_set(InputIterator f, InputIterator l, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_set(f, l, n, hf, key_equal(), a) { }
unordered_set(initializer_list<value_type> il, size_type n, const allocator_type& a)
: unordered_set(il, n, hasher(), key_equal(), a) { }
unordered_set(initializer_list<value_type> il, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_set(il, n, hf, key_equal(), a) { }
~unordered_set();
unordered_set& operator=(const unordered_set&);
unordered_set& operator=(unordered_set&&);
unordered_set& operator=(initializer_list<value_type>);
allocator_type get_allocator() const noexcept;
bool empty() const noexcept;
size_type size() const noexcept;
size_type max_size() const noexcept;
iterator begin() noexcept;
const_iterator begin() const noexcept;
iterator end() noexcept;
const_iterator end() const noexcept;
const_iterator cbegin() const noexcept;
const_iterator cend() const noexcept;
template <class... Args> pair<iterator, bool> emplace(Args&&... args);
template <class... Args> iterator emplace_hint(const_iterator position, Args&&... args);
pair<iterator, bool> insert(const value_type& obj);
pair<iterator, bool> insert(value_type&& obj);
iterator insert(const_iterator hint, const value_type& obj);
iterator insert(const_iterator hint, value_type&& obj);
template <class InputIterator> void insert(InputIterator first, InputIterator last);
void insert(initializer_list<value_type>);
iterator erase(const_iterator position);
size_type erase(const key_type& k);
iterator erase(const_iterator first, const_iterator last);
void clear() noexcept;
void swap(unordered_set&);
hasher hash_function() const;
key_equal key_eq() const;
iterator find(const key_type& k);
const_iterator find(const key_type& k) const;
size_type count(const key_type& k) const;
std::pair<iterator, iterator> equal_range(const key_type& k);
std::pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
size_type bucket_count() const noexcept;
size_type max_bucket_count() const noexcept;
size_type bucket_size(size_type n) const;
size_type bucket(const key_type& k) const;
local_iterator begin(size_type n);
const_local_iterator begin(size_type n) const;
local_iterator end(size_type n);
const_local_iterator end(size_type n) const;
const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
float load_factor() const noexcept;
float max_load_factor() const noexcept;
void max_load_factor(float z);
void rehash(size_type n);
void reserve(size_type n);
};
template <class Key, class Hash, class Pred, class Alloc>
void swap(unordered_set<Key, Hash, Pred, Alloc>& x,
unordered_set<Key, Hash, Pred, Alloc>& y);
template <class Key, class Hash, class Pred, class Alloc>
bool operator==(const unordered_set<Key, Hash, Pred, Alloc>& a,
const unordered_set<Key, Hash, Pred, Alloc>& b);
template <class Key, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_set<Key, Hash, Pred, Alloc>& a,
const unordered_set<Key, Hash, Pred, Alloc>& b);
}
23.5.6.2 unordered_set constructors [unord.set.cnstr]
unordered_set() : unordered_set(size_type(see below)) { } explicit unordered_set(size_type n, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_set using the specified hash function, key equality function, and allocator, and using at least n buckets. For the default constructor, the number of buckets is implementation-defined. max_load_factor() returns 1.0.
template <class InputIterator> unordered_set(InputIterator f, InputIterator l, size_type n = see below, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_set using the specified hash function, key equality function, and allocator, and using at least n buckets. If n is not provided, the number of buckets is implementation-defined. Then inserts elements from the range [f, l). max_load_factor() returns 1.0.
Complexity: Average case linear, worst case quadratic.
23.5.6.3 unordered_set swap [unord.set.swap] template <class Key, class Hash, class Pred, class Alloc> void swap(unordered_set<Key, Hash, Pred, Alloc>& x, unordered_set<Key, Hash, Pred, Alloc>& y);
An unordered_multiset is an unordered associative container that supports equivalent keys (an instance of unordered_multiset may contain multiple copies of the same key value) and in which each element's key is the element itself. The unordered_multiset class supports forward iterators.
An unordered_multiset satisfies all of the requirements of a container, of an unordered associative container, and of an allocator-aware container (Table [tab:containers.allocatoraware]). It provides the operations described in the preceding requirements table for equivalent keys; that is, an unordered_multiset supports the a_eq operations in that table, not the a_uniq operations. For an unordered_multiset<Key> the key type and the value type are both Key. The iterator and const_iterator types are both const iterator types. It is unspecified whether they are the same type.
This section only describes operations on unordered_multiset that are not described in one of the requirement tables, or for which there is additional semantic information.
namespace std {
template <class Key,
class Hash = hash<Key>,
class Pred = std::equal_to<Key>,
class Allocator = std::allocator<Key> >
class unordered_multiset
{
public:
typedef Key key_type;
typedef Key value_type;
typedef Hash hasher;
typedef Pred key_equal;
typedef Allocator allocator_type;
typedef typename allocator_traits<Allocator>::pointer pointer;
typedef typename allocator_traits<Allocator>::const_pointer const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef implementation-defined size_type;
typedef implementation-defined difference_type;
typedef implementation-defined iterator;
typedef implementation-defined const_iterator;
typedef implementation-defined local_iterator;
typedef implementation-defined const_local_iterator;
unordered_multiset();
explicit unordered_multiset(size_type n,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template <class InputIterator>
unordered_multiset(InputIterator f, InputIterator l,
size_type n = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_multiset(const unordered_multiset&);
unordered_multiset(unordered_multiset&&);
explicit unordered_multiset(const Allocator&);
unordered_multiset(const unordered_multiset&, const Allocator&);
unordered_multiset(unordered_multiset&&, const Allocator&);
unordered_multiset(initializer_list<value_type>,
size_type = see below,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_multiset(size_type n, const allocator_type& a)
: unordered_multiset(n, hasher(), key_equal(), a) { }
unordered_multiset(size_type n, const hasher& hf, const allocator_type& a)
: unordered_multiset(n, hf, key_equal(), a) { }
template <class InputIterator>
unordered_multiset(InputIterator f, InputIterator l, size_type n, const allocator_type& a)
: unordered_multiset(f, l, n, hasher(), key_equal(), a) { }
template <class InputIterator>
unordered_multiset(InputIterator f, InputIterator l, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_multiset(f, l, n, hf, key_equal(), a) { }
unordered_multiset(initializer_list<value_type> il, size_type n, const allocator_type& a)
: unordered_multiset(il, n, hasher(), key_equal(), a) { }
unordered_multiset(initializer_list<value_type> il, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_multiset(il, n, hf, key_equal(), a) { }
~unordered_multiset();
unordered_multiset& operator=(const unordered_multiset&);
unordered_multiset& operator=(unordered_multiset&&);
unordered_multiset& operator=(initializer_list<value_type>);
allocator_type get_allocator() const noexcept;
bool empty() const noexcept;
size_type size() const noexcept;
size_type max_size() const noexcept;
iterator begin() noexcept;
const_iterator begin() const noexcept;
iterator end() noexcept;
const_iterator end() const noexcept;
const_iterator cbegin() const noexcept;
const_iterator cend() const noexcept;
template <class... Args> iterator emplace(Args&&... args);
template <class... Args> iterator emplace_hint(const_iterator position, Args&&... args);
iterator insert(const value_type& obj);
iterator insert(value_type&& obj);
iterator insert(const_iterator hint, const value_type& obj);
iterator insert(const_iterator hint, value_type&& obj);
template <class InputIterator> void insert(InputIterator first, InputIterator last);
void insert(initializer_list<value_type>);
iterator erase(const_iterator position);
size_type erase(const key_type& k);
iterator erase(const_iterator first, const_iterator last);
void clear() noexcept;
void swap(unordered_multiset&);
hasher hash_function() const;
key_equal key_eq() const;
iterator find(const key_type& k);
const_iterator find(const key_type& k) const;
size_type count(const key_type& k) const;
std::pair<iterator, iterator> equal_range(const key_type& k);
std::pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
size_type bucket_count() const noexcept;
size_type max_bucket_count() const noexcept;
size_type bucket_size(size_type n) const;
size_type bucket(const key_type& k) const;
local_iterator begin(size_type n);
const_local_iterator begin(size_type n) const;
local_iterator end(size_type n);
const_local_iterator end(size_type n) const;
const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
float load_factor() const noexcept;
float max_load_factor() const noexcept;
void max_load_factor(float z);
void rehash(size_type n);
void reserve(size_type n);
};
template <class Key, class Hash, class Pred, class Alloc>
void swap(unordered_multiset<Key, Hash, Pred, Alloc>& x,
unordered_multiset<Key, Hash, Pred, Alloc>& y);
template <class Key, class Hash, class Pred, class Alloc>
bool operator==(const unordered_multiset<Key, Hash, Pred, Alloc>& a,
const unordered_multiset<Key, Hash, Pred, Alloc>& b);
template <class Key, class Hash, class Pred, class Alloc>
bool operator!=(const unordered_multiset<Key, Hash, Pred, Alloc>& a,
const unordered_multiset<Key, Hash, Pred, Alloc>& b);
}
23.5.7.2 unordered_multiset constructors [unord.multiset.cnstr]
unordered_multiset() : unordered_multiset(size_type(see below)) { } explicit unordered_multiset(size_type n, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_multiset using the specified hash function, key equality function, and allocator, and using at least n buckets. For the default constructor, the number of buckets is implementation-defined. max_load_factor() returns 1.0.
template <class InputIterator> unordered_multiset(InputIterator f, InputIterator l, size_type n = see below, const hasher& hf = hasher(), const key_equal& eql = key_equal(), const allocator_type& a = allocator_type());
Effects: Constructs an empty unordered_multiset using the specified hash function, key equality function, and allocator, and using at least n buckets. If n is not provided, the number of buckets is implementation-defined. Then inserts elements from the range [f, l). max_load_factor() returns 1.0.
Complexity: Average case linear, worst case quadratic.
23.5.7.3 unordered_multiset swap [unord.multiset.swap] template <class Key, class Hash, class Pred, class Alloc> void swap(unordered_multiset<Key, Hash, Pred, Alloc>& x, unordered_multiset<Key, Hash, Pred, Alloc>& y);
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