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deductiongu...rstd::deque(3)   C++ Standard Libary  deductiongu...rstd::deque(3)

NAME
     deductionguidesforstd::deque - deductionguidesforstd::deque

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

		  class Alloc = std::allocator<
		      typename std::iterator_traits<InputIt>::value_type>
	>								     (1)
     (since C++17)
	deque( InputIt, InputIt, Alloc = Alloc() )

	    -> deque<typename std::iterator_traits<InputIt>::value_type,
	Alloc>;
	template< ranges::input_range R,

		  class Alloc = std::allocator<ranges::range_value_t<R>>  >  (2)
     (since C++23)
	deque( std::from_range_t, R&&, Alloc = Alloc() )

	    -> deque<ranges::range_value_t<R>, Alloc>;

	1) This deduction guide is provided for deque to allow deduction from an
     iterator
	range. This overload participates in overload resolution only if InputIt
     satisfies
	LegacyInputIterator and Alloc satisfies Allocator.
	2) This deduction guide is provided for deque to allow deduction from a
	std::from_range_t tag and an input_range.

	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 (2)

Example
     // Run this code

      #include <deque>
      #include <vector>

      int main()
      {
	  std::vector<int> v = {1, 2, 3, 4};

	  // uses explicit deduction guide to deduce std::deque<int>
	  std::deque x(v.begin(), v.end());

	  // deduces std::deque<std::vector<int>::iterator>
	  //  first phase of overload resolution for list-initialization selects
     the candidate
	  // synthesized from the initializer-list constructor; second phase  is
     not performed
	  // and deduction guide has no effect
	  std::deque y{v.begin(), v.end()};
      }

http://cppreference.com 	   2024.06.10	    deductiongu...rstd::deque(3)
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