std::destroy - cppreference.com (original) (raw)

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

Destroys the objects in the range [first, last), as if by
Same as (1), but executed according to policy. This overload participates in overload resolution only if all following conditions are satisfied:

[edit] 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.

[edit] Complexity

Linear in the distance between first and last.

[edit] 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.

[edit] Possible implementation

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

[edit] Example

The following example demonstrates how to use destroy to destroy a contiguous sequence of elements.

#include #include #include 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::destroy(ptr, ptr + 8); }

Output:

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