std::destroy_n

 

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Defined in header <memory>
template< class ForwardIt, class Size > ForwardIt destroy_n( ForwardIt first, Size n );	(1)	(since C++17)
template< class ExecutionPolicy, class ForwardIt, class Size > ForwardIt destroy_n( ExecutionPolicy&& policy, ForwardIt first, Size n );	(2)	(since C++17)

1) Destroys the n objects in the range starting at first, as if by

for (; n > 0; (void) ++first, --n)
  std::destroy_at(std::addressof(*first));

2) Same as (1), but executed according to policy. This overload does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true

Parameters

first	-	the beginning of the range of elements to destroy
n	-	the number of elements to destroy
policy	-	the execution policy to use. See execution policy for details.
Type requirements
- ForwardIt must meet the requirements of ForwardIterator.
- No increment, assignment, comparison, or indirection through valid instances of ForwardIt may throw exceptions.

Return value

The end of the range of objects that has been destroyed (i.e., std::next(first, n)).

Complexity

Linear in n.

Exceptions

The overload with a template parameter named ExecutionPolicy reports errors as follows:

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

Possible implementation

template<class ForwardIt, class Size> ForwardIt destroy_n( ForwardIt first, Size n ) { for (; n > 0; (void) ++first, --n) std::destroy_at(std::addressof(*first)); return first; }

See also

destroy (C++17)	destroys a range of objects (function template)
destroy_at (C++17)	destroys an object at a given address (function template)