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std:: destroy

From cppreference.net
C++
Memory management library
( exposition only* )
Allocators
Uninitialized memory algorithms
Constrained uninitialized memory algorithms
Memory resources
Uninitialized storage (until C++20)
( until C++20* )
( until C++20* )
( until C++20* )

Garbage collector support (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
(C++11) (until C++23)
Defined in header <memory>
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)
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)

Contents

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.

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++20
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 <iostream>
#include <memory>
#include <new>
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

See also

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