std::destroy

 

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Defined in header <memory>
	(1)
template<class ForwardIt > void destroy( ForwardIt first, ForwardIt last );			(since C++17) (until C++20)
template<class ForwardIt > constexprvoid destroy( ForwardIt first, ForwardIt last );			(since C++20)
template<class ExecutionPolicy, class ForwardIt > void destroy( ExecutionPolicy&& policy, ForwardIt first, ForwardIt last );		(2)	(since C++17)

1) Destroys the objects in the range [first, last), as if by

for(; first != last;++first)std::destroy_at(std::addressof(*first));

2) Same as (1), but executed according to policy. This overload participates in overload resolution only if all following conditions are satisfied:

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 pair of iterators defining the range of elements to destroy
policy	-	the execution policy to use
Type requirements
- ForwardIt must meet the requirements of LegacyForwardIterator.
- No increment, assignment, comparison, or indirection through valid instances of ForwardIt may throw exceptions.

Return value

(none)

Complexity

Linear in the distance between first and last.

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 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>constexpr// since C++20void destroy(ForwardIt first, ForwardIt last){for(; first != last;++first)std::destroy_at(std::addressof(*first));}

Example

The following example demonstrates how to use destroy to destroy 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)unsignedchar 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::destroy(ptr, ptr +8);}

Output:

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

See also

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