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

NAME
     std::uninitialized_copy - std::uninitialized_copy

Synopsis
	Defined in header <memory>
	template< class InputIt, class NoThrowForwardIt >

	NoThrowForwardIt uninitialized_copy( InputIt first, InputIt last,  (1)

					     NoThrowForwardIt d_first );
	template< class ExecutionPolicy, class ForwardIt, class
	NoThrowForwardIt >

	NoThrowForwardIt  uninitialized_copy(  ExecutionPolicy&& policy,     (2)
     (since C++17)
					     ForwardIt first, ForwardIt
	last,

					     NoThrowForwardIt d_first );

	1) Copies elements from the range [first, last) to an uninitialized mem-
     ory area
	beginning at d_first as if by for (; first !=  last;  ++d_first,  (void)
     ++first)
	    ::new (/* VOIDIFY */(*d_first))
		typename			std::iterator_traits<NoThrowFor-
     wardIt>::value_type(*first);
	where /* VOIDIFY */(e) is:

	static_cast<void*>(&e)		      (until C++11)
	static_cast<void*>(std::addressof(e)) (since C++11)

	If an exception is thrown during the initialization, the objects already
     constructed
	are destroyed in an unspecified order.

	If   d_first   +   [0,	 std::distance(first,	last))	 overlaps   with
     (since C++20)
	[first, last), the behavior is undefined.

	2) Same as (1), but executed according to policy. This overload partici-
     pates in
	overload resolution only if

	std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>    is    true.
     (until
										  C++20)
	std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>      is
     true. (since
										  C++20)

Parameters
	first, last	      -        the range of the elements to copy
	d_first 	      -        the beginning of the destination range
	policy		       -	 the execution policy to use. See execu-
     tion policy for
				       details.

Type requirements
	-
	InputIt must meet the requirements of LegacyInputIterator.
	-
	ForwardIt must meet the requirements of LegacyForwardIterator.
	-
	NoThrowForwardIt must meet the requirements of LegacyForwardIterator.
	-
	No increment, assignment, comparison, or indirection through  valid  in-
     stances of
	NoThrowForwardIt may throw exceptions.
	Applying  &*  to  a  NoThrowForwardIt  value must yield a pointer to its
     value type.
	(until C++11)

Return value
	Iterator to the element past the last element copied.

Complexity
	Linear in the distance between first and last.

Exceptions
	The overload with a template parameter named ExecutionPolicy reports er-
     rors as
	follows:

	  * If execution of a function invoked as part of the  algorithm  throws
     an exception
	    and  ExecutionPolicy is one of the standard policies, std::terminate
     is called.
	    For any other ExecutionPolicy, the	behavior  is  implementation-de-
     fined.
	  * If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation
     template<class InputIt, class NoThrowForwardIt> NoThrowForwardIt uninitial-
     ized_copy(InputIt first, InputIt last, NoThrowForwardIt d_first) {
	 using T = typename std::iterator_traits<NoThrowForwardIt>::value_type;
	 NoThrowForwardIt current = d_first;
	 try
	 {
	     for (; first != last; ++first, (void) ++current)
		 ::new (static_cast<void*>(std::addressof(*current))) T(*first);
	     return current;
	 }
	 catch (...)
	 {
	     for (; d_first != current; ++d_first)
		 d_first->~T();
	     throw;
	 } }

Example
     // Run this code

      #include <cstdlib>
      #include <iostream>
      #include <memory>
      #include <string>

      int main()
      {
	  const char *v[] = {"This", "is", "an", "example"};

	  auto sz = std::size(v);

	  if	 (void	  *pbuf    =	std::aligned_alloc(alignof(std::string),
     sizeof(std::string) * sz))
	  {
	      try
	      {
		  auto first = static_cast<std::string*>(pbuf);
		  auto	   last     =	  std::uninitialized_copy(std::begin(v),
     std::end(v), first);

		  for (auto it = first; it != last; ++it)
		      std::cout << *it << '_';
		  std::cout << '\n';

		  std::destroy(first, last);
	      }
	      catch (...) {}
	      std::free(pbuf);
	  }
      }

Output:
      This_is_an_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
			    given T as the value type of
	LWG  866  C++98      NoThrowForwardIt, if		     uses global
     replacement-
			    T::operator new exists, the program     new instead
			    might be ill-formed
			    the effect description used a for loop
			    with the iteration			    discards the
     value
	LWG 2133 C++98	     expression  ++d_first,  ++first,  which	 of  one
     operand
			    results				     to  disable
     that ADL
			    in an argument-dependent lookup of
			    operator,
	LWG 2433  C++11       this  algorithm  might  be  hijacked  by	    uses
     std::addressof
			    overloaded operator&
	LWG  3870 C++20      this algorithm might create objects on  kept disal-
     lowed
			    a const storage

See also
	uninitialized_copy_n	   copies a number of objects to  an  uninitial-
     ized area of
	(C++11) 		   memory
				   (function template)
	ranges::uninitialized_copy copies a range of objects to an uninitialized
     area of
	(C++20) 		   memory
				   (niebloid)

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