Standard library header <map>
This header is part of the containers library.
Includes |
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(C++20)
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Three-way comparison operator support |
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(C++11)
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std::initializer_list class template |
Classes |
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| collection of key-value pairs, sorted by keys, keys are unique (class template) |
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| collection of key-value pairs, sorted by keys (class template) |
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Functions |
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(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20)
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lexicographically compares the values in the map (function template) |
specializes the std::swap algorithm (function template) |
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(C++20)
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Erases all elements satisfying specific criteria (function template) |
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(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20)
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lexicographically compares the values in the multimap (function template) |
specializes the std::swap algorithm (function template) |
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(C++20)
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Erases all elements satisfying specific criteria (function template) |
Range access |
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(C++11)(C++14)
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returns an iterator to the beginning of a container or array (function template) |
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(C++11)(C++14)
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returns an iterator to the end of a container or array (function template) |
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(C++14)
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returns a reverse iterator to the beginning of a container or array (function template) |
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(C++14)
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returns a reverse end iterator for a container or array (function template) |
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(C++17)(C++20)
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returns the size of a container or array (function template) |
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(C++17)
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checks whether the container is empty (function template) |
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(C++17)
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obtains the pointer to the underlying array (function template) |
Synopsis
#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)));
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)));
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>>>;
}
}
Class template 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 {
friend class map;
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 InputIt>
map(InputIt first, InputIt last,
const Compare& comp = Compare(), const Allocator& = Allocator());
map(const map& x);
map(map&& x);
explicit map(const Allocator&);
map(const map&, const Allocator&);
map(map&&, const Allocator&);
map(initializer_list<value_type>,
const Compare& = Compare(),
const Allocator& = Allocator());
template<class InputIt>
map(InputIt first, InputIt last, const Allocator& a)
: map(first, last, 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
[[nodiscard]] 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);
mapped_type& at(const key_type& x);
const mapped_type& at(const key_type& 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 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);
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... 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& 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 InputIt, class Compare = less</*iter-key-type*/<InputIt>>,
class Allocator = allocator</*iter-to-alloc-type*/<InputIt>>>
map(InputIt, InputIt, Compare = Compare(), Allocator = Allocator())
-> map</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>,
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 InputIt, class Allocator>
map(InputIt, InputIt, Allocator)
-> map</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>,
less</*iter-key-type*/<InputIt>>, Allocator>;
template<class Key, class T, class Allocator>
map(initializer_list<pair<Key, T>>, Allocator) -> map<Key, T, less<Key>, Allocator>;
// swap
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)));
}
Class template 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 {
friend class multimap;
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 InputIt>
multimap(InputIt first, InputIt last,
const Compare& comp = Compare(),
const Allocator& = Allocator());
multimap(const multimap& x);
multimap(multimap&& x);
explicit multimap(const Allocator&);
multimap(const multimap&, const Allocator&);
multimap(multimap&&, const Allocator&);
multimap(initializer_list<value_type>,
const Compare& = Compare(),
const Allocator& = Allocator());
template<class InputIt>
multimap(InputIt first, InputIt last, const Allocator& a)
: multimap(first, last, 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
[[nodiscard]] 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 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);
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 InputIt, class Compare = less</*iter-key-type*/<InputIt>>,
class Allocator = allocator</*iter-to-alloc-type*/<InputIt>>>
multimap(InputIt, InputIt, Compare = Compare(), Allocator = Allocator())
-> multimap</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>,
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 InputIt, class Allocator>
multimap(InputIt, InputIt, Allocator)
-> multimap</*iter-key-type*/<InputIt>, /*iter-mapped-type*/<InputIt>,
less</*iter-key-type*/<InputIt>>, Allocator>;
template<class Key, class T, class Allocator>
multimap(initializer_list<pair<Key, T>>, Allocator)
-> multimap<Key, T, less<Key>, Allocator>;
// swap
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)));
}
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