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deductiongu...td::multimap(3)  C++ Standard Libary deductiongu...td::multimap(3)

NAME
     deductionguidesforstd::multimap - deductionguidesforstd::multimap

Synopsis
	Defined in header <map>
	template< class InputIt,

		  class Comp = std::less<iter_key_t<InputIt>>,
		  class Alloc =
	std::allocator<iter_to_alloc_t<InputIt>> >		      (1) (since
     C++17)
	multimap( InputIt, InputIt, Comp = Comp(), Alloc = Alloc() )

	    -> multimap<iter_key_t<InputIt>, iter_val_t<InputIt>,
	Comp, Alloc>;
	template< class Key,

		  class T,
		  class Comp = std::less<Key>,
		  class Alloc = std::allocator<std::pair<const Key,   (2) (since
     C++17)
	T>> >
	multimap( std::initializer_list<std::pair<Key, T>>, Comp =
	Comp(), Alloc = Alloc() )

	    -> multimap<Key, T, Comp, Alloc>;
	template< class InputIt, class Alloc >

	multimap( InputIt, InputIt, Alloc )			      (3) (since
     C++17)
	    -> multimap<iter_key_t<InputIt>, iter_val_t<InputIt>,

			std::less<iter_key_t<InputIt>>, Alloc>;
	template< class Key, class T, class Alloc >

	multimap( std::initializer_list<std::pair<Key, T>>, Alloc )   (4) (since
     C++17)

	    -> multimap<Key, T, std::less<Key>, Alloc>;
	template< ranges::input_range R, class Compare =
	std::less<range_key_t<R>,

		  class Alloc = std::allocator<range_to_alloc_t<R>> >
	multimap( std::from_range_t, R&&, Compare = Compare(), Alloc  (5) (since
     C++23)
	= Alloc() )

	    -> multimap<range_key_t<R>, range_mapped_t<R>, Compare,
	Alloc>;
	template< ranges::input_range R, class Alloc >

	multimap( std::from_range_t, R&&, Alloc )		      (6) (since
     C++23)

	    -> multimap<range_key_t<R>, range_mapped_t<R>,
	std::less<range_key_t<R>>, Alloc>;
	Exposition-only helper type aliases
	template< class InputIter >

	using iter_val_t =						  (expo-
     sition only*)

	    typename std::iterator_traits<InputIter>::value_type;
	template< class InputIter >

	using iter_key_t =						  (expo-
     sition only*)

	    std::remove_const_t< std::tuple_element_t<0,
	iter_val_t<InputIter>>>;
	template< class InputIter >

	using iter_mapped_t =						  (expo-
     sition only*)

	    std::tuple_element_t<1, iter_val_t<InputIter>>;
	template< class InputIter >

	using iter_to_alloc_t =
	    std::pair<std::add_const_t<tuple_element_t<0,		  (expo-
     sition only*)
	iter_val_t<InputIter>>>,

		      std::tuple_element_t<1,
	iter_val_t<InputIter>>>;
	template< ranges::input_range Range >

	using range_key_t =						  (since
     C++23)
									  (expo-
     sition only*)
	    std::remove_const_t<typename
	ranges::range_value_t<Range>::first_type>;
	template< ranges::input_range Range >
									  (since
     C++23)
	using range_mapped_t =						  (expo-
     sition only*)

	    typename ranges::range_value_t<Range>::second_type;
	template< ranges::input_range Range >

	using range_to_alloc_t =
	    std::pair<std::add_const_t<typename 			  (since
     C++23)
	ranges::range_value_t<Range>::first_type>,			  (expo-
     sition only*)

		      typename
	ranges::range_value_t<Range>::second_type>;

	1-4) These deduction guides are provided for multimap to allow deduction
     from an
	iterator  range  (overloads  (1,3)) and std::initializer_list (overloads
     (2,4)).
	5,6) These deduction guides are provided for multimap to allow deduction
     from a
	std::from_range_t tag and an input_range.

	These overloads participate in overload resolution only if InputIt  sat-
     isfies
	LegacyInputIterator,  Alloc  satisfies Allocator, and Comp does not sat-
     isfy Allocator.

	Note: the extent to which the library determines that a  type  does  not
     satisfy
	LegacyInputIterator  is  unspecified,  except that as a minimum integral
     types do not
	qualify as input iterators. Likewise, the extent to which it  determines
     that a type
	does  not satisfy Allocator is unspecified, except that as a minimum the
     member type
	Alloc::value_type must exist and the expression
	std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed  when
     treated as
	an unevaluated operand.

Notes
	    Feature-test macro	     Value    Std		    Feature
	__cpp_lib_containers_ranges  202202L  (C++23)  Ranges-aware construction
     and insertion;
						    overload (5,6)

Example
     // Run this code

      #include <map>

      int main()
      {
	  // std::multimap m1 = {{"foo", 1}, {"bar", 2}};
	      // Error: braced-init-list has no type; cannot deduce
	      // pair<Key, T> from {"foo", 1} or {"bar", 2}

	  std::multimap m1 = {std::pair{"foo", 2}, {"bar", 3}}; // guide #2
	  std::multimap m2(m1.begin(), m1.end()); // guide #1
      }

	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
	LWG  3025  C++17       initializer-list  guides  take		     use
     std::pair<Key, T>
			    std::pair<const Key, T>

http://cppreference.com 	   2024.06.10	   deductiongu...td::multimap(3)
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