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std::multimap(3)	       C++ Standard Libary		std::multimap(3)

NAME
     std::multimap - std::multimap

Synopsis
	Defined in header <map>
	template<

	    class Key,
	    class T,							   (1)
	    class Compare = std::less<Key>,
	    class Allocator = std::allocator<std::pair<const Key, T>>

	> class multimap;
	namespace pmr {

	    template<
		class Key,
		class  T,						     (2)
     (since C++17)
		class Compare = std::less<Key>
	    > using multimap = std::multimap<Key, T, Compare,
		std::pmr::polymorphic_allocator<std::pair<const Key, T>>>;

	}

	std::multimap is an associative container that contains a sorted list of
     key-value
	pairs, while permitting multiple entries with the same key.  Sorting  is
     done
	according  to  the  comparison	function  Compare,  applied to the keys.
     Search,
	insertion, and removal operations have logarithmic complexity.

	Iterators of std::multimap iterate  in	non-descending	order  of  keys,
     where
	non-descending	is defined by the comparison that was used for construc-
     tion. That is,
	given

	  * m, a std::multimap
	  * it_l and it_r, dereferenceable iterators to m, with it_l < it_r.

	m.value_comp()(*it_r, *it_l) == false (least to greatest  if  using  the
     default
	comparison).

	The  order  of	the key-value pairs whose keys compare equivalent is the
     (since C++11)
	order of insertion and does not change.

	Everywhere the standard library uses the Compare  requirements,  equiva-
     lence is
	determined by using the equivalence relation as described on Compare. In
     imprecise
	terms, two objects a and b are considered equivalent if neither compares
     less than
	the other: !comp(a, b) && !comp(b, a).

	std::multimap  meets  the  requirements of Container, AllocatorAwareCon-
     tainer,
	AssociativeContainer and ReversibleContainer.

Template parameters
	 This section is incomplete
	 Reason: Add descriptions of the template parameters.

Member types
	Member type		Definition
	key_type		Key
	mapped_type		T
	value_type		std::pair<const Key, T>
	size_type		Unsigned integer type (usually std::size_t)
	difference_type 	Signed integer type (usually std::ptrdiff_t)
	key_compare		Compare
	allocator_type		Allocator
	reference		value_type&
	const_reference 	const value_type&
				Allocator::pointer			  (until
     C++11)
	pointer 		std::allocator_traits<Allocator>::pointer (since
     C++11)

				Allocator::const_pointer
     (until
										C++11)
	const_pointer		 std::allocator_traits<Allocator>::const_pointer
     (since
										C++11)

	iterator		LegacyBidirectionalIterator to value_type
	const_iterator		LegacyBidirectionalIterator to const value_type
	reverse_iterator	std::reverse_iterator<iterator>
	const_reverse_iterator	std::reverse_iterator<const_iterator>
	node_type  (since  C++17) a specialization of node handle representing a
     container
				node

Member classes
	value_compare compares objects of type value_type
		      (class)

Member functions
	constructor   constructs the multimap
		      (public member function)
	destructor    destructs the multimap
		      (public member function)
	operator=     assigns values to the container
		      (public member function)
	get_allocator returns the associated allocator
		      (public member function)

Iterators
	begin	      returns an iterator to the beginning
	cbegin	      (public member function)
	(C++11)
	end	      returns an iterator to the end
	cend	      (public member function)
	(C++11)
	rbegin	      returns a reverse iterator to the beginning
	crbegin       (public member function)
	(C++11)
	rend	      returns a reverse iterator to the end
	crend	      (public member function)
	(C++11)

Capacity
	empty	      checks whether the container is empty
		      (public member function)
	size	      returns the number of elements
		      (public member function)
	max_size      returns the maximum possible number of elements
		      (public member function)

Modifiers
	clear	      clears the contents
		      (public member function)
		      inserts elements
	insert	      or nodes
		      (since C++17)
		      (public member function)
	insert_range  inserts a range of elements
	(C++23)       (public member function)
	emplace       constructs element in-place
	(C++11)       (public member function)
	emplace_hint  constructs elements in-place using a hint
	(C++11)       (public member function)
	erase	      erases elements
		      (public member function)
	swap	      swaps the contents
		      (public member function)
	extract       extracts nodes from the container
	(C++17)       (public member function)
	merge	      splices nodes from another container
	(C++17)       (public member function)

Lookup
	count	      returns the number of elements matching specific key
		      (public member function)
	find	      finds element with specific key
		      (public member function)
	contains      checks if the container contains element with specific key
	(C++20)       (public member function)
	equal_range   returns range of elements matching a specific key
		      (public member function)
	lower_bound   returns an iterator to the first element not less than the
     given key
		      (public member function)
	upper_bound   returns an iterator to the first element greater than  the
     given key
		      (public member function)

Observers
	key_comp      returns the function that compares keys
		      (public member function)
	value_comp    returns the function that compares keys in objects of type
     value_type
		      (public member function)

Non-member functions
	operator==
	operator!=
	operator<
	operator<=
	operator>
	operator>=		  lexicographically  compares  the values of two
     multimaps
	operator<=>		 (function template)
	(removed in C++20)
	(removed in C++20)
	(removed in C++20)
	(removed in C++20)
	(removed in C++20)
	(C++20)
	std::swap(std::multimap) specializes the std::swap algorithm
				 (function template)
	erase_if(std::multimap)  erases all elements satisfying specific  crite-
     ria
	(C++20) 		 (function template)

	  Deduction guides (since C++17)

Notes
	    Feature-test macro	     Value    Std		    Feature
	__cpp_lib_containers_ranges  202202L (C++23) Ranges construction and in-
     sertion for
						    containers

Example
	 This section is incomplete
	 Reason: no example

	Defect reports

	The following behavior-changing defect	reports  were  applied	retroac-
     tively to
	previously published C++ standards.

	  DR	 Applied to	      Behavior as published		 Correct
     behavior
			   Key was not required to be
	LWG 230 C++98	   CopyConstructible			     Key is also
     required to
			   (a key of type Key might not be able to   be CopyCon-
     structible
			   be constructed)

Categories:
	  * Todo with reason
	  * Todo no example

http://cppreference.com 	   2024.06.10			std::multimap(3)
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