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std::ranges::destroy_n(3)      C++ Standard Libary     std::ranges::destroy_n(3)

NAME
     std::ranges::destroy_n - std::ranges::destroy_n

Synopsis
	Defined in header <memory>
	Call signature
	template< no-throw-input-iterator I >

	    requires			 std::destructible<std::iter_value_t<I>>
     (since C++20)

	constexpr I destroy_n( I first, std::iter_difference_t<I> n )
	noexcept;

	Destroys the n objects in the range starting at first, equivalent to

      return  std::ranges::destroy(std::counted_iterator(first,   n),	std::de-
     fault_sentinel).base();

	The  function-like  entities  described on this page are niebloids, that
     is:

	  * Explicit template argument lists cannot be	specified  when  calling
     any of them.
	  * None of them are visible to argument-dependent lookup.
	  *  When any of them are found by normal unqualified lookup as the name
     to the left
	    of the function-call operator, argument-dependent lookup  is  inhib-
     ited.

	In  practice,  they may be implemented as function objects, or with spe-
     cial compiler
	extensions.

Parameters
	first - the beginning of the range of elements to destroy
	n     - the number of elements to destroy

Return value
	The end of the range of objects that has been destroyed.

Complexity
	Linear in n.

Possible implementation
	struct destroy_n_fn
	{
	    template<no-throw-input-iterator I>
		requires std::destructible<std::iter_value_t<I>>
	    constexpr I operator()(I first, std::iter_difference_t<I>  n)  const
     noexcept
	    {
		for (; n != 0; (void)++first, --n)
		    std::ranges::destroy_at(std::addressof(*first));
		return first;
	    }
	};

	inline constexpr destroy_n_fn destroy_n{};

Example
	The  following	example demonstrates how to use ranges::destroy_n to de-
     stroy a
	contiguous sequence of elements.

     // Run this code

      #include <iostream>
      #include <memory>
      #include <new>

      struct Tracer
      {
	  int value;
	  ~Tracer() { std::cout << value << " destructed\n"; }
      };

      int main()
      {
	  alignas(Tracer) unsigned char buffer[sizeof(Tracer) * 8];

	  for (int i = 0; i < 8; ++i)
	      new(buffer + sizeof(Tracer) * i) Tracer{i};  //manually  construct
     objects

	  auto ptr = std::launder(reinterpret_cast<Tracer*>(buffer));

	  std::ranges::destroy_n(ptr, 8);
      }

Output:
      0 destructed
      1 destructed
      2 destructed
      3 destructed
      4 destructed
      5 destructed
      6 destructed
      7 destructed

See also
	ranges::destroy_at destroys an object at a given address
	(C++20) 	   (niebloid)
	ranges::destroy    destroys a range of objects
	(C++20) 	   (niebloid)
	destroy_n	   destroys a number of objects in a range
	(C++17) 	   (function template)

http://cppreference.com 	   2024.06.10	       std::ranges::destroy_n(3)
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