Std::destroy (3) Linux Manual Page

std::destroy – std::destroy

Synopsis

Defined in header<memory>

    template <class ForwardIt>
    (1)(since C++ 17)

        void destroy(ForwardIt first, ForwardIt last);

template <class ExecutionPolicy, class ForwardIt>
(2)(since C++ 17)

    void destroy(ExecutionPolicy &&policy, ForwardIt first, ForwardIt last);

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 does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true.

Parameters

first, last – the range of elements to destroy
policy – the execution policy to use. See execution_policy for details.

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 >
  void 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 <memory>

#include <new>

#include <iostream>
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

std::destroy (3) Linux Manual Page