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标准库头文件 <map>

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标准库头文件
语言支持
概念
<concepts> (C++20)
诊断
<system_error> (C++11)

内存管理
<memory_resource> (C++17)  
元编程
<type_traits> (C++11)
<ratio> (C++11)
通用实用程序
<utility>
<tuple> (C++11)
<optional> (C++17)
<variant> (C++17)
<any> (C++17)
<debugging> (C++26)
<expected> (C++23)
<bitset>
<charconv> (C++17)
<format> (C++20)
<bit> (C++20)

字符串
<cuchar> (C++11)

容器
<flat_set> (C++23)
<span> (C++20)
<mdspan> (C++23)
<inplace_vector> (C++26)
迭代器
<iterator>
范围
<ranges> (C++20)
<generator> (C++23)
算法
数值
<cfenv> (C++11)
<complex>
<cmath>
<linalg> (C++26)
<numbers> (C++20)

时间
<chrono> (C++11)
本地化
<codecvt> (C++11/17/26*)
<text_encoding> (C++26)
输入/输出
<filesystem> (C++17)
<cstdio>
<cinttypes> (C++11)
<strstream> (C++98/26*)
正则表达式
<regex> (C++11)
并发支持
<stop_token> (C++20)
<thread> (C++11)
<atomic> (C++11)
<rcu> (C++26)
<stdatomic.h> (C++23)
<mutex> (C++11)
<shared_mutex> (C++14)

<condition_variable> (C++11)  
<semaphore> (C++20)
<latch> (C++20)

<barrier> (C++20)
<future> (C++11)
<hazard_pointer> (C++26)

C 兼容性
<cstdbool> (C++11/17/20*)  
<ccomplex> (C++11/17/20*)
<ctgmath> (C++11/17/20*)

<cstdalign> (C++11/17/20*)

<ciso646> (直到 C++20)

 

此头文件是 容器 库的一部分。

内容

包含

(C++20)
三路比较运算符 支持[编辑]
std::initializer_list 类模板[编辑]

键值对集合,按键排序,键唯一
(类模板) [编辑]
键值对集合,按键排序
(类模板) [编辑]

函数

(C++20 中移除)(C++20 中移除)(C++20 中移除)(C++20 中移除)(C++20 中移除)(C++20)
按字典序比较两个 map 的值
(函数模板) [编辑]
专门化 std::swap 算法
(函数模板) [编辑]
删除所有满足特定条件的元素
(函数模板) [编辑]
(C++20 中移除)(C++20 中移除)(C++20 中移除)(C++20 中移除)(C++20 中移除)(C++20)
按字典序比较两个 multimap 的值
(函数模板) [编辑]
专门化 std::swap 算法
(函数模板) [编辑]
删除所有满足特定条件的元素
(函数模板) [编辑]
范围访问
(C++11)(C++14)
返回指向容器或数组开头的迭代器
(函数模板) [编辑]
(C++11)(C++14)
返回指向容器或数组末尾的迭代器
(函数模板) [编辑]
返回指向容器或数组开头的反向迭代器
(函数模板) [编辑]
(C++14)
返回容器或数组的反向末尾迭代器
(函数模板) [编辑]
(C++17)(C++20)
返回容器或数组的大小
(函数模板) [编辑]
(C++17)
检查容器是否为空
(函数模板) [编辑]
(C++17)
获取指向底层数组的指针
(函数模板) [编辑]

[编辑] 概要

#include <compare>
#include <initializer_list>
 
namespace std {
  // class template map
  template<class Key,
           class T,
           class Compare   = less<Key>,
           class Allocator = allocator<pair<const Key, T>>>
  class map;
 
  template<class Key, class T, class Compare, class Allocator>
  bool operator==(const map<Key, T, Compare, Allocator>& x,
                  const map<Key, T, Compare, Allocator>& y);
  template<class Key, class T, class Compare, class Allocator>
  /*synth-three-way-result*/<pair<const Key, T>> operator<=>(
    const map<Key, T, Compare, Allocator>& x,
    const map<Key, T, Compare, Allocator>& y);
 
  template<class Key, class T, class Compare, class Allocator>
  void swap(map<Key, T, Compare, Allocator>& x,
            map<Key, T, Compare, Allocator>& y) noexcept(noexcept(x.swap(y)));
 
  // erasure for map
  template<class Key, class T, class Compare, class Allocator, class Predicate>
  typename map<Key, T, Compare, Allocator>::size_type erase_if(
    map<Key, T, Compare, Allocator>& c,
    Predicate pred);
 
  // class template multimap
  template<class Key,
           class T,
           class Compare   = less<Key>,
           class Allocator = allocator<pair<const Key, T>>>
  class multimap;
 
  template<class Key, class T, class Compare, class Allocator>
  bool operator==(const multimap<Key, T, Compare, Allocator>& x,
                  const multimap<Key, T, Compare, Allocator>& y);
  template<class Key, class T, class Compare, class Allocator>
  /*synth-three-way-result*/<pair<const Key, T>> operator<=>(
    const multimap<Key, T, Compare, Allocator>& x,
    const multimap<Key, T, Compare, Allocator>& y);
 
  template<class Key, class T, class Compare, class Allocator>
  void swap(multimap<Key, T, Compare, Allocator>& x,
            multimap<Key, T, Compare, Allocator>& y) noexcept(noexcept(x.swap(y)));
 
  // erasure for multimap
  template<class Key, class T, class Compare, class Allocator, class Predicate>
  typename multimap<Key, T, Compare, Allocator>::size_type erase_if(
    multimap<Key, T, Compare, Allocator>& c,
    Predicate pred);
 
  namespace pmr {
    template<class Key, class T, class Compare = less<Key>>
    using map = std::map<Key, T, Compare, polymorphic_allocator<pair<const Key, T>>>;
 
    template<class Key, class T, class Compare = less<Key>>
    using multimap =
      std::multimap<Key, T, Compare, polymorphic_allocator<pair<const Key, T>>>;
  }
}

[编辑] 类模板 std::map

namespace std {
  template<class Key,
           class T,
           class Compare   = less<Key>,
           class Allocator = allocator<pair<const Key, T>>>
  class map
  {
  public:
    // types
    using key_type               = Key;
    using mapped_type            = T;
    using value_type             = pair<const Key, T>;
    using key_compare            = Compare;
    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 reverse_iterator       = std::reverse_iterator<iterator>;
    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
    using node_type              = /* unspecified */;
    using insert_return_type     = /*insert-return-type*/<iterator, node_type>;
 
    class value_compare
    {
    protected:
      Compare comp;
      value_compare(Compare c)
        : comp(c)
      {
      }
 
    public:
      bool operator()(const value_type& x, const value_type& y) const
      {
        return comp(x.first, y.first);
      }
    };
 
    // construct/copy/destroy
    map()
      : map(Compare())
    {
    }
    explicit map(const Compare& comp, const Allocator& = Allocator());
    template<class InputIter>
    map(InputIter first,
        InputIter last,
        const Compare& comp = Compare(),
        const Allocator&    = Allocator());
    template<container-compatible-range<value_type> R>
    map(from_range_t,
        R&& rg,
        const Compare& comp = Compare(),
        const Allocator&    = Allocator());
    map(const map& x);
    map(map&& x);
    explicit map(const Allocator&);
    map(const map&, const type_identity_t<Allocator>&);
    map(map&&, const type_identity_t<Allocator>&);
    map(initializer_list<value_type>,
        const Compare&   = Compare(),
        const Allocator& = Allocator());
    template<class InputIter>
    map(InputIter first, InputIter last, const Allocator& a)
      : map(first, last, Compare(), a)
    {
    }
    template<container-compatible-range<value_type> R>
      map(from_range_t, R&& rg, const Allocator& a))
        : map(from_range, std::forward<R>(rg), Compare(), a)
    {
    }
    map(initializer_list<value_type> il, const Allocator& a)
      : map(il, Compare(), a)
    {
    }
    ~map();
    map& operator=(const map& x);
    map& operator=(map&& x) noexcept(allocator_traits<Allocator>::is_always_equal::value&&
                                       is_nothrow_move_assignable_v<Compare>);
    map& operator=(initializer_list<value_type>);
    allocator_type get_allocator() const noexcept;
 
    // iterators
    iterator begin() noexcept;
    const_iterator begin() const noexcept;
    iterator end() noexcept;
    const_iterator end() const noexcept;
 
    reverse_iterator rbegin() noexcept;
    const_reverse_iterator rbegin() const noexcept;
    reverse_iterator rend() noexcept;
    const_reverse_iterator rend() const noexcept;
 
    const_iterator cbegin() const noexcept;
    const_iterator cend() const noexcept;
    const_reverse_iterator crbegin() const noexcept;
    const_reverse_iterator crend() const noexcept;
 
    // capacity
    bool empty() const noexcept;
    size_type size() const noexcept;
    size_type max_size() const noexcept;
 
    // element access
    mapped_type& operator[](const key_type& x);
    mapped_type& operator[](key_type&& x);
    template<class K>
    mapped_type& operator[](K&& x);
    mapped_type& at(const key_type& x);
    const mapped_type& at(const key_type& x) const;
    template<class K>
    mapped_type& at(const K& x);
    template<class K>
    const mapped_type& at(const K& x) const;
 
    // modifiers
    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& x);
    pair<iterator, bool> insert(value_type&& x);
    template<class P>
    pair<iterator, bool> insert(P&& x);
    iterator insert(const_iterator position, const value_type& x);
    iterator insert(const_iterator position, value_type&& x);
    template<class P>
    iterator insert(const_iterator position, P&&);
    template<class InputIter>
    void insert(InputIter first, InputIter last);
    template<container-compatible-range<value_type> R>
    void insert_range(R&& rg);
    void insert(initializer_list<value_type>);
 
    node_type extract(const_iterator position);
    node_type extract(const key_type& x);
    template<class K>
    node_type extract(K&& 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 K, class... Args>
    pair<iterator, bool> try_emplace(K&& 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 K, class... Args>
    iterator try_emplace(const_iterator hint, K&& 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 K, class M>
    pair<iterator, bool> insert_or_assign(K&& 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);
    template<class K, class M>
    iterator insert_or_assign(const_iterator hint, K&& k, M&& obj);
 
    iterator erase(iterator position);
    iterator erase(const_iterator position);
    size_type erase(const key_type& x);
    template<class K>
    size_type erase(K&& x);
    iterator erase(const_iterator first, const_iterator last);
    void swap(map&) noexcept(allocator_traits<Allocator>::is_always_equal::value&&
                               is_nothrow_swappable_v<Compare>);
    void clear() noexcept;
 
    template<class C2>
    void merge(map<Key, T, C2, Allocator>& source);
    template<class C2>
    void merge(map<Key, T, C2, Allocator>&& source);
    template<class C2>
    void merge(multimap<Key, T, C2, Allocator>& source);
    template<class C2>
    void merge(multimap<Key, T, C2, Allocator>&& source);
 
    // observers
    key_compare key_comp() const;
    value_compare value_comp() const;
 
    // map operations
    iterator find(const key_type& x);
    const_iterator find(const key_type& x) const;
    template<class K>
    iterator find(const K& x);
    template<class K>
    const_iterator find(const K& x) const;
 
    size_type count(const key_type& x) const;
    template<class K>
    size_type count(const K& x) const;
 
    bool contains(const key_type& x) const;
    template<class K>
    bool contains(const K& x) const;
 
    iterator lower_bound(const key_type& x);
    const_iterator lower_bound(const key_type& x) const;
    template<class K>
    iterator lower_bound(const K& x);
    template<class K>
    const_iterator lower_bound(const K& x) const;
 
    iterator upper_bound(const key_type& x);
    const_iterator upper_bound(const key_type& x) const;
    template<class K>
    iterator upper_bound(const K& x);
    template<class K>
    const_iterator upper_bound(const K& x) const;
 
    pair<iterator, iterator> equal_range(const key_type& x);
    pair<const_iterator, const_iterator> equal_range(const key_type& x) const;
    template<class K>
    pair<iterator, iterator> equal_range(const K& x);
    template<class K>
    pair<const_iterator, const_iterator> equal_range(const K& x) const;
  };
 
  template<class InputIter,
           class Compare   = less</*iter-key-type*/<InputIter>>,
           class Allocator = allocator</*iter-to-alloc-type*/<InputIter>>>
  map(InputIter, InputIter, Compare = Compare(), Allocator = Allocator())
    -> map</*iter-key-type*/<InputIter>,
           /*iter-mapped-type*/<InputIter>,
           Compare,
           Allocator>;
 
  template<
    ranges::input_range R,
    class Compare =
      less</*range-key-type*/<R>, class Allocator = allocator</*range-to-alloc-type*/<R>>>
        map(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
          -> map</*range-key-type*/<R>, /*range-mapped-type*/<R>, Compare, Allocator>;
 
  template<class Key,
           class T,
           class Compare   = less<Key>,
           class Allocator = allocator<pair<const Key, T>>>
  map(initializer_list<pair<Key, T>>, Compare = Compare(), Allocator = Allocator())
    -> map<Key, T, Compare, Allocator>;
 
  template<class InputIter, class Allocator>
  map(InputIter, InputIter, Allocator) -> map</*iter-key-type*/<InputIter>,
                                              /*iter-mapped-type*/<InputIter>,
                                              less</*iter-key-type*/<InputIter>>,
                                              Allocator>;
 
  template<ranges::input_range R, class Allocator>
  map(from_range_t, R&&, Allocator) -> map</*range-key-type*/<R>,
                                           /*range-mapped-type*/<R>,
                                           less</*range-key-type*/<R>>,
                                           Allocator>;
 
  template<class Key, class T, class Allocator>
  map(initializer_list<pair<Key, T>>, Allocator) -> map<Key, T, less<Key>, Allocator>;
}

[编辑] 类模板 std::multimap

namespace std {
  template<class Key,
           class T,
           class Compare   = less<Key>,
           class Allocator = allocator<pair<const Key, T>>>
  class multimap
  {
  public:
    // types
    using key_type               = Key;
    using mapped_type            = T;
    using value_type             = pair<const Key, T>;
    using key_compare            = Compare;
    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 reverse_iterator       = std::reverse_iterator<iterator>;
    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
    using node_type              = /* unspecified */;
 
    class value_compare
    {
    protected:
      Compare comp;
      value_compare(Compare c)
        : comp(c)
      {
      }
 
    public:
      bool operator()(const value_type& x, const value_type& y) const
      {
        return comp(x.first, y.first);
      }
    };
 
    // construct/copy/destroy
    multimap()
      : multimap(Compare())
    {
    }
    explicit multimap(const Compare& comp, const Allocator& = Allocator());
    template<class InputIter>
    multimap(InputIter first,
             InputIter last,
             const Compare& comp = Compare(),
             const Allocator&    = Allocator());
    template<container-compatible-range<value_type> R>
    multimap(from_range_t,
             R&& rg,
             const Compare& comp = Compare(),
             const Allocator&    = Allocator());
    multimap(const multimap& x);
    multimap(multimap&& x);
    explicit multimap(const Allocator&);
    multimap(const multimap&, const type_identity_t<Allocator>&);
    multimap(multimap&&, const type_identity_t<Allocator>&);
    multimap(initializer_list<value_type>,
             const Compare&   = Compare(),
             const Allocator& = Allocator());
    template<class InputIter>
    multimap(InputIter first, InputIter last, const Allocator& a)
      : multimap(first, last, Compare(), a)
    {
    }
    template<container-compatible-range<value_type> R>
      multimap(from_range_t, R&& rg, const Allocator& a))
        : multimap(from_range, std::forward<R>(rg), Compare(), a)
    {
    }
    multimap(initializer_list<value_type> il, const Allocator& a)
      : multimap(il, Compare(), a)
    {
    }
    ~multimap();
    multimap& operator=(const multimap& x);
    multimap& operator=(multimap&& x) noexcept(
      allocator_traits<Allocator>::is_always_equal::value&&
        is_nothrow_move_assignable_v<Compare>);
    multimap& operator=(initializer_list<value_type>);
    allocator_type get_allocator() const noexcept;
 
    // iterators
    iterator begin() noexcept;
    const_iterator begin() const noexcept;
    iterator end() noexcept;
    const_iterator end() const noexcept;
 
    reverse_iterator rbegin() noexcept;
    const_reverse_iterator rbegin() const noexcept;
    reverse_iterator rend() noexcept;
    const_reverse_iterator rend() const noexcept;
 
    const_iterator cbegin() const noexcept;
    const_iterator cend() const noexcept;
    const_reverse_iterator crbegin() const noexcept;
    const_reverse_iterator crend() const noexcept;
 
    // capacity
    bool empty() const noexcept;
    size_type size() const noexcept;
    size_type max_size() const noexcept;
 
    // modifiers
    template<class... Args>
    iterator emplace(Args&&... args);
    template<class... Args>
    iterator emplace_hint(const_iterator position, Args&&... args);
    iterator insert(const value_type& x);
    iterator insert(value_type&& x);
    template<class P>
    iterator insert(P&& x);
    iterator insert(const_iterator position, const value_type& x);
    iterator insert(const_iterator position, value_type&& x);
    template<class P>
    iterator insert(const_iterator position, P&& x);
    template<class InputIter>
    void insert(InputIter first, InputIter last);
    template<container-compatible-range<value_type> R>
    void insert_range(R&& rg);
    void insert(initializer_list<value_type>);
 
    node_type extract(const_iterator position);
    node_type extract(const key_type& x);
    template<class K>
    node_type extract(K&& 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& x);
    template<class K>
    size_type erase(K&& x);
    iterator erase(const_iterator first, const_iterator last);
    void swap(multimap&) noexcept(allocator_traits<Allocator>::is_always_equal::value&&
                                    is_nothrow_swappable_v<Compare>);
    void clear() noexcept;
 
    template<class C2>
    void merge(multimap<Key, T, C2, Allocator>& source);
    template<class C2>
    void merge(multimap<Key, T, C2, Allocator>&& source);
    template<class C2>
    void merge(map<Key, T, C2, Allocator>& source);
    template<class C2>
    void merge(map<Key, T, C2, Allocator>&& source);
 
    // observers
    key_compare key_comp() const;
    value_compare value_comp() const;
 
    // map operations
    iterator find(const key_type& x);
    const_iterator find(const key_type& x) const;
    template<class K>
    iterator find(const K& x);
    template<class K>
    const_iterator find(const K& x) const;
 
    size_type count(const key_type& x) const;
    template<class K>
    size_type count(const K& x) const;
 
    bool contains(const key_type& x) const;
    template<class K>
    bool contains(const K& x) const;
 
    iterator lower_bound(const key_type& x);
    const_iterator lower_bound(const key_type& x) const;
    template<class K>
    iterator lower_bound(const K& x);
    template<class K>
    const_iterator lower_bound(const K& x) const;
 
    iterator upper_bound(const key_type& x);
    const_iterator upper_bound(const key_type& x) const;
    template<class K>
    iterator upper_bound(const K& x);
    template<class K>
    const_iterator upper_bound(const K& x) const;
 
    pair<iterator, iterator> equal_range(const key_type& x);
    pair<const_iterator, const_iterator> equal_range(const key_type& x) const;
    template<class K>
    pair<iterator, iterator> equal_range(const K& x);
    template<class K>
    pair<const_iterator, const_iterator> equal_range(const K& x) const;
  };
 
  template<class InputIter,
           class Compare   = less</*iter-key-type*/<InputIter>>,
           class Allocator = allocator</*iter-to-alloc-type*/<InputIter>>>
  multimap(InputIter, InputIter, Compare = Compare(), Allocator = Allocator())
    -> multimap</*iter-key-type*/<InputIter>,
                /*iter-mapped-type*/<InputIter>,
                Compare,
                Allocator>;
 
  template<ranges::input_range R,
           class Compare   = less</*range-key-type*/<R>>,
           class Allocator = allocator</*range-to-alloc-type*/<R>>>
  multimap(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
    -> multimap</*range-key-type*/<R>, /*range-mapped-type*/<R>, Compare, Allocator>;
 
  template<class Key,
           class T,
           class Compare   = less<Key>,
           class Allocator = allocator<pair<const Key, T>>>
  multimap(initializer_list<pair<Key, T>>, Compare = Compare(), Allocator = Allocator())
    -> multimap<Key, T, Compare, Allocator>;
 
  template<class InputIter, class Allocator>
  multimap(InputIter, InputIter, Allocator)
    -> multimap</*iter-key-type*/<InputIter>,
                /*iter-mapped-type*/<InputIter>,
                less</*iter-key-type*/<InputIter>>,
                Allocator>;
 
  template<ranges::input_range R, class Allocator>
  multimap(from_range_t, R&&, Allocator) -> multimap</*range-key-type*/<R>,
                                                     /*range-mapped-type*/<R>,
                                                     less</*range-key-type*/<R>>,
                                                     Allocator>;
 
  template<class Key, class T, class Allocator>
  multimap(initializer_list<pair<Key, T>>, Allocator)
    -> multimap<Key, T, less<Key>, Allocator>;
}

[编辑] 缺陷报告

以下行为变更缺陷报告被追溯应用于先前发布的 C++ 标准。

DR 应用于 已发布的行为 正确行为
LWG 133 C++98 map::get_allocator 在概要中缺失 添加