標準ライブラリヘッダ <unordered_map>

 

C++

言語

標準ライブラリヘッダ

フリースタンディング処理系とホスト処理系

名前付き要件

言語サポートライブラリ

コンセプトライブラリ(C++20)

診断ライブラリ

ユーティリティライブラリ

文字列ライブラリ

コンテナライブラリ

イテレータライブラリ

範囲ライブラリ(C++20)

アルゴリズムライブラリ

数値演算ライブラリ

ローカライゼーションライブラリ

入出力ライブラリ

ファイルシステムライブラリ(C++17)

正規表現ライブラリ(C++11)

アトミック操作ライブラリ(C++11)

スレッドサポートライブラリ(C++11)

技術仕様書

 

標準ライブラリヘッダ

言語サポート
<cstddef> <cstdlib> <version> <limits> <climits>	<cfloat> <cstdint> <new> <typeinfo>	<source_location> <exception> <initializer_list> <compare>	<coroutine> <csignal> <csetjmp> <cstdarg>
コンセプト
<concepts>
診断
<stdexcept>	<cassert>	<cerrno>	<system_error>
汎用ユーティリティ
<utility> <memory> <memory_resource> <scoped_allocator>	<bitset> <tuple> <optional> <any>	<variant> <type_traits> <ratio> <chrono>	<typeindex> <functional> <ctime>
文字列
<string> <string_view> <cstring>	<charconv> <format>	<cctype> <cwctype>	<cwchar> <cuchar>
ローカライゼーション
<locale>	<codecvt>	<clocale>
コンテナ
<span> <array> <vector>	<deque> <forward_list> <list>	<map> <set> <queue>	<unordered_map> <unordered_set> <stack>
イテレータ
<iterator>
範囲
<ranges>
アルゴリズム
<algorithm>	<execution>
数値演算
<complex> <random>	<valarray> <numeric>	<bit> <numbers>	<cfenv> <cmath>
入出力
<iosfwd> <ios> <iomanip> <streambuf>	<istream> <ostream> <iostream>	<sstream> <spanstream> <fstream> <syncstream>	<cstdio> <cinttypes> <strstream>
正規表現
<regex>
ファイルシステムサポート
<filesystem>
スレッドサポート
<thread> <atomic> <mutex>	<shared_mutex> <condition_variable> <future>	<stop_token> <semaphore>	<latch> <barrier>
C互換
<ciso646> <cstdalign>	<cstdbool> <ccomplex>	<ctgmath> <stdatomic.h>

 

このヘッダはコンテナライブラリの一部です。

インクルード
<compare> (C++20)	三方比較演算子サポート
<initializer_list> (C++11)	std::initializer_list クラステンプレート
クラス
unordered_map (C++11)	一意なキーによってハッシュされた、キー値ペアのコレクション (クラステンプレート)
unordered_multimap (C++11)	キーによってハッシュされた、キー値ペアのコレクション (クラステンプレート)
関数
operator==operator!= (C++20で削除)	unordered_map 内の値を比較します (関数テンプレート)
std::swap(std::unordered_map) (C++11)	std::swap アルゴリズムの特殊化 (関数テンプレート)
erase_if(std::unordered_map) (C++20)	特定の基準を満たすすべての要素を削除します (関数テンプレート)
operator==operator!= (C++20で削除)	unordered_multimap 内の値を比較します (関数テンプレート)
std::swap(std::unordered_multimap) (C++11)	std::swap アルゴリズムの特殊化 (関数テンプレート)
erase_if(std::unordered_multimap) (C++20)	特定の基準を満たすすべての要素を削除します (関数テンプレート)
範囲アクセス
begincbegin (C++11)(C++14)	コンテナまたは配列の先頭を指すイテレータを返します (関数)
endcend (C++11)(C++14)	コンテナまたは配列の終端を指すイテレータを返します (関数)
rbegincrbegin (C++14)	コンテナまたは配列の先頭を指す逆イテレータを返します (関数)
rendcrend (C++14)	コンテナまたは配列の終端を指す逆イテレータを返します (関数)
sizessize (C++17)(C++20)	コンテナまたは配列のサイズを返します (関数テンプレート)
empty (C++17)	コンテナが空かどうか調べます (関数)
data (C++17)	ベースとなる配列を指すポインタを取得します (関数)

概要

#include <compare>#include <initializer_list>   namespace std {// class template unordered_­maptemplate<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>, class Alloc = allocator<pair<const Key, T>>>class unordered_map;   // class template unordered_­multimaptemplate<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>, class Alloc = allocator<pair<const Key, T>>>class unordered_multimap;   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>void swap(unordered_map<Key, T, Hash, Pred, Alloc>& x, unordered_map<Key, T, Hash, Pred, Alloc>& y)noexcept(noexcept(x.swap(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)noexcept(noexcept(x.swap(y)));   template<class K, class T, class H, class P, class A, class Predicate>typename unordered_map<K, T, H, P, A>::size_type erase_if(unordered_map<K, T, H, P, A>& c, Predicate pred);   template<class K, class T, class H, class P, class A, class Predicate>typename unordered_multimap<K, T, H, P, A>::size_type erase_if(unordered_multimap<K, T, H, P, A>& c, Predicate pred);   namespace pmr {template<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>>using unordered_map =std::unordered_map<Key, T, Hash, Pred, polymorphic_allocator<pair<const Key, T>>>;template<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>>using unordered_multimap =std::unordered_multimap<Key, T, Hash, Pred, polymorphic_allocator<pair<const Key, T>>>;   }}

クラステンプレート std::unordered_map

namespace std {template<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>, class Allocator = allocator<pair<const Key, T>>>class unordered_map {public:// typesusing key_type = Key;using mapped_type = T;using value_type = pair<const Key, T>;using hasher = Hash;using key_equal = Pred;using allocator_type = Allocator;using pointer =typename allocator_traits<Allocator>::pointer;using const_pointer =typename allocator_traits<Allocator>::const_pointer;using reference = value_type&;using const_reference =const value_type&;using size_type =/* implementation-defined */;using difference_type =/* implementation-defined */;   using iterator =/* implementation-defined */;using const_iterator =/* implementation-defined */;using local_iterator =/* implementation-defined */;using const_local_iterator =/* implementation-defined */;using node_type =/* unspecified */;using insert_return_type =/*insert-return-type*/<iterator, node_type>;   // construct/copy/destroy 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 InputIt> unordered_map(InputIt f, InputIt l, size_type n =/* see description */, 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> il, size_type n =/* see description */, 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 InputIt> unordered_map(InputIt f, InputIt l, size_type n, const allocator_type& a): unordered_map(f, l, n, hasher(), key_equal(), a){}template<class InputIt> unordered_map(InputIt f, InputIt 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&&)noexcept(allocator_traits<Allocator>::is_always_equal::value&& is_nothrow_move_assignable_v<Hash>&& is_nothrow_move_assignable_v<Pred>); unordered_map& operator=(initializer_list<value_type>); allocator_type get_allocator()constnoexcept;   // iterators iterator begin()noexcept; const_iterator begin()constnoexcept; iterator end()noexcept; const_iterator end()constnoexcept; const_iterator cbegin()constnoexcept; const_iterator cend()constnoexcept;   // capacity[[nodiscard]]bool empty()constnoexcept; size_type size()constnoexcept; size_type max_size()constnoexcept;   // modifierstemplate<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);template<class P> pair<iterator, bool> insert(P&& obj); iterator insert(const_iterator hint, const value_type& obj); iterator insert(const_iterator hint, value_type&& obj);template<class P> iterator insert(const_iterator hint, P&& obj);template<class InputIt>void insert(InputIt first, InputIt last);void insert(initializer_list<value_type>);   node_type extract(const_iterator position); node_type extract(const key_type& x); insert_return_type insert(node_type&& nh); iterator insert(const_iterator hint, node_type&& nh);   template<class... Args> pair<iterator, bool> try_emplace(const key_type& k, Args&&... args);template<class... Args> pair<iterator, bool> try_emplace(key_type&& k, Args&&... args);template<class... Args> iterator try_emplace(const_iterator hint, const key_type& k, Args&&... args);template<class... Args> iterator try_emplace(const_iterator hint, key_type&& k, Args&&... args);template<class M> pair<iterator, bool> insert_or_assign(const key_type& k, M&& obj);template<class M> pair<iterator, bool> insert_or_assign(key_type&& k, M&& obj);template<class M> iterator insert_or_assign(const_iterator hint, const key_type& k, M&& obj);template<class M> iterator insert_or_assign(const_iterator hint, key_type&& k, M&& obj);   iterator erase(iterator position); iterator erase(const_iterator position); size_type erase(const key_type& k); iterator erase(const_iterator first, const_iterator last);void swap(unordered_map&)noexcept(allocator_traits<Allocator>::is_always_equal::value&& is_nothrow_swappable_v<Hash>&& is_nothrow_swappable_v<Pred>);void clear()noexcept;   template<class H2, class P2>void merge(unordered_map<Key, T, H2, P2, Allocator>& source);template<class H2, class P2>void merge(unordered_map<Key, T, H2, P2, Allocator>&& source);template<class H2, class P2>void merge(unordered_multimap<Key, T, H2, P2, Allocator>& source);template<class H2, class P2>void merge(unordered_multimap<Key, T, H2, P2, Allocator>&& source);   // observers hasher hash_function()const; key_equal key_eq()const;   // map operations iterator find(const key_type& k); const_iterator find(const key_type& k)const;template<class K> iterator find(const K& k);template<class K> const_iterator find(const K& k)const;template<class K> size_type count(const key_type& k)const;template<class K> size_type count(const K& k)const;bool contains(const key_type& k)const;template<class K>bool contains(const K& k)const; pair<iterator, iterator> equal_range(const key_type& k); pair<const_iterator, const_iterator> equal_range(const key_type& k)const;template<class K> pair<iterator, iterator> equal_range(const K& k);template<class K> pair<const_iterator, const_iterator> equal_range(const K& k)const;   // element access 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;   // bucket interface size_type bucket_count()constnoexcept; size_type max_bucket_count()constnoexcept; 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;   // hash policyfloat load_factor()constnoexcept;float max_load_factor()constnoexcept;void max_load_factor(float z);void rehash(size_type n);void reserve(size_type n);};   template<class InputIt, class Hash = hash</*iter-key-type*/<InputIt>>, class Pred = equal_to</*iter-key-type*/<InputIt>>, class Allocator = allocator</*iter-to-alloc-type*/<InputIt>>> unordered_map(InputIt, InputIt, typename/* see description */::size_type=/* see description */, Hash = Hash(), Pred = Pred(), Allocator = Allocator())-> unordered_map</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>, Hash, Pred, Allocator>;   template<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>, class Allocator = allocator<pair<const Key, T>>> unordered_map(initializer_list<pair<Key, T>>, typename/* see description */::size_type=/* see description */, Hash = Hash(), Pred = Pred(), Allocator = Allocator())-> unordered_map<Key, T, Hash, Pred, Allocator>;   template<class InputIt, class Allocator> unordered_map(InputIt, InputIt, typename/* see description */::size_type, Allocator)-> unordered_map</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>, hash</*iter-key-type*/<InputIt>>, equal_to</*iter-key-type*/<InputIt>>, Allocator>;   template<class InputIt, class Allocator> unordered_map(InputIt, InputIt, Allocator)-> unordered_map</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIte>, hash</*iter-key-type*/<InputIt>>, equal_to</*iter-key-type*/<InputIt>>, Allocator>;   template<class InputIt, class Hash, class Allocator> unordered_map(InputIt, InputIt, typename/* see description */::size_type, Hash, Allocator)-> unordered_map</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>, Hash, equal_to</*iter-key-type*/<InputIt>>, Allocator>;   template<class Key, class T, class Allocator> unordered_map(initializer_list<pair<Key, T>>, typename/* see description */::size_type, Allocator)-> unordered_map<Key, T, hash<Key>, equal_to<Key>, Allocator>;   template<class Key, class T, class Allocator> unordered_map(initializer_list<pair<Key, T>>, Allocator)-> unordered_map<Key, T, hash<Key>, equal_to<Key>, Allocator>;   template<class Key, class T, class Hash, class Allocator> unordered_map(initializer_list<pair<Key, T>>, typename/* see description */::size_type, Hash, Allocator)-> unordered_map<Key, T, Hash, equal_to<Key>, Allocator>;   // swaptemplate<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)noexcept(noexcept(x.swap(y)));}

クラステンプレート std::unordered_multimap

namespace std {template<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>, class Allocator = allocator<pair<const Key, T>>>class unordered_multimap {public:// typesusing key_type = Key;using mapped_type = T;using value_type = pair<const Key, T>;using hasher = Hash;using key_equal = Pred;using allocator_type = Allocator;using pointer =typename allocator_traits<Allocator>::pointer;using const_pointer =typename allocator_traits<Allocator>::const_pointer;using reference = value_type&;using const_reference =const value_type&;using size_type =/* implementation-defined */;using difference_type =/* implementation-defined */;   using iterator =/* implementation-defined */;using const_iterator =/* implementation-defined */;using local_iterator =/* implementation-defined */;using const_local_iterator =/* implementation-defined */;using node_type =/* unspecified */;   // construct/copy/destroy 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 InputIt> unordered_multimap(InputIt f, InputIt l, size_type n =/* see description */, 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> il, size_type n =/* see description */, 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 InputIt> unordered_multimap(InputIt f, InputIt l, size_type n, const allocator_type& a): unordered_multimap(f, l, n, hasher(), key_equal(), a){}template<class InputIt> unordered_multimap(InputIt f, InputIt 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&&)noexcept(allocator_traits<Allocator>::is_always_equal::value&& is_nothrow_move_assignable_v<Hash>&& is_nothrow_move_assignable_v<Pred>); unordered_multimap& operator=(initializer_list<value_type>); allocator_type get_allocator()constnoexcept;   // iterators iterator begin()noexcept; const_iterator begin()constnoexcept; iterator end()noexcept; const_iterator end()constnoexcept; const_iterator cbegin()constnoexcept; const_iterator cend()constnoexcept;   // capacity[[nodiscard]]bool empty()constnoexcept; size_type size()constnoexcept; size_type max_size()constnoexcept;   // modifierstemplate<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);template<class P> iterator insert(P&& obj); iterator insert(const_iterator hint, const value_type& obj); iterator insert(const_iterator hint, value_type&& obj);template<class P> iterator insert(const_iterator hint, P&& obj);template<class InputIt>void insert(InputIt first, InputIt last);void insert(initializer_list<value_type>);   node_type extract(const_iterator position); node_type extract(const key_type& x); iterator insert(node_type&& nh); iterator insert(const_iterator hint, node_type&& nh);   iterator erase(iterator position); iterator erase(const_iterator position); size_type erase(const key_type& k); iterator erase(const_iterator first, const_iterator last);void swap(unordered_multimap&)noexcept(allocator_traits<Allocator>::is_always_equal::value&& is_nothrow_swappable_v<Hash>&& is_nothrow_swappable_v<Pred>);void clear()noexcept;   template<class H2, class P2>void merge(unordered_multimap<Key, T, H2, P2, Allocator>& source);template<class H2, class P2>void merge(unordered_multimap<Key, T, H2, P2, Allocator>&& source);template<class H2, class P2>void merge(unordered_map<Key, T, H2, P2, Allocator>& source);template<class H2, class P2>void merge(unordered_map<Key, T, H2, P2, Allocator>&& source);   // observers hasher hash_function()const; key_equal key_eq()const;   // map operations iterator find(const key_type& k); const_iterator find(const key_type& k)const;template<class K> iterator find(const K& k);template<class K> const_iterator find(const K& k)const; size_type count(const key_type& k)const;template<class K> size_type count(const K& k)const;bool contains(const key_type& k)const;template<class K>bool contains(const K& k)const; pair<iterator, iterator> equal_range(const key_type& k); pair<const_iterator, const_iterator> equal_range(const key_type& k)const;template<class K> pair<iterator, iterator> equal_range(const K& k);template<class K> pair<const_iterator, const_iterator> equal_range(const K& k)const;   // bucket interface size_type bucket_count()constnoexcept; size_type max_bucket_count()constnoexcept; 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;   // hash policyfloat load_factor()constnoexcept;float max_load_factor()constnoexcept;void max_load_factor(float z);void rehash(size_type n);void reserve(size_type n);};   template<class InputIt, class Hash = hash</*iter-key-type*/<InputIt>>, class Pred = equal_to</*iter-key-type*/<InputIt>>, class Allocator = allocator</*iter-to-alloc-type*/<InputIt>>> unordered_multimap(InputIt, InputIt, typename/* see description */::size_type=/* see description */, Hash = Hash(), Pred = Pred(), Allocator = Allocator())-> unordered_multimap<iter-key-type<InputIt>, iter-mapped-type<InputIt>, Hash, Pred, Allocator>;   template<class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>, class Allocator = allocator<pair<const Key, T>>> unordered_multimap(initializer_list<pair<Key, T>>, typename/* see description */::size_type=/* see description */, Hash = Hash(), Pred = Pred(), Allocator = Allocator())-> unordered_multimap<Key, T, Hash, Pred, Allocator>;   template<class InputIt, class Allocator> unordered_multimap(InputIt, InputIt, typename/* see description */::size_type, Allocator)-> unordered_multimap</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>, hash</*iter-key-type*/<InputIt>>, equal_to</*iter-key-type*/<InputIt>>, Allocator>;   template<class InputIt, class Allocator> unordered_multimap(InputIt, InputIt, Allocator)-> unordered_multimap</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>, hash</*iter-key-type*/<InputIt>>, equal_to</*iter-key-type*/<InputIt>>, Allocator>;   template<class InputIt, class Hash, class Allocator> unordered_multimap(InputIt, InputIt, typename/* see description */::size_type, Hash, Allocator)-> unordered_multimap</*iter-key-type*/<InputIt>, iter-mapped-type<InputIt>, Hash, equal_to</*iter-key-type*/<InputIt>>, Allocator>;   template<class Key, class T, class Allocator> unordered_multimap(initializer_list<pair<Key, T>>, typename/* see description */::size_type, Allocator)-> unordered_multimap<Key, T, hash<Key>, equal_to<Key>, Allocator>;   template<class Key, class T, class Allocator> unordered_multimap(initializer_list<pair<Key, T>>, Allocator)-> unordered_multimap<Key, T, hash<Key>, equal_to<Key>, Allocator>;   template<class Key, class T, class Hash, class Allocator> unordered_multimap(initializer_list<pair<Key, T>>, typename/* see description */::size_type, Hash, Allocator)-> unordered_multimap<Key, T, Hash, equal_to<Key>, Allocator>;   // swaptemplate<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)noexcept(noexcept(x.swap(y)));}