std::destroy
From cppreference.com
| Defined in header <memory>
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template< class ForwardIt >
void destroy( ForwardIt first, ForwardIt last );
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(1) | (since C++17) (until C++20) |
template< class ForwardIt >
constexpr void destroy( ForwardIt first, ForwardIt last );
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(since C++20) | |
template< class ExecutionPolicy, class ForwardIt >
void destroy( ExecutionPolicy&& policy, ForwardIt first, ForwardIt last );
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(2) | (since C++17) |
1) Destroys elements in the target 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 the value of the following expression is
true:
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(until C++20) |
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(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.
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-No increment, assignment, comparison, or indirection through valid instances of ForwardIt may throw exceptions.
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Exceptions
2) During the execution process:
- If the temporary memory resources required for parallelization are not available, std::bad_alloc is thrown.
- If an uncaught exception is thrown while accessing objects via an algorithm argument, the behavior is determined by the execution policy (for standard policies, std::terminate is invoked).
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));
}
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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 & algorithm function object) |
(C++20) |
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(C++17) |
destroys an object at a given address (function template & algorithm function object) |
(C++20) |
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(C++20) |
destroys a range of objects (algorithm function object) |