std::destroy_at
From cppreference.com
Defined in header <memory>
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template< class T > void destroy_at( T* p ); |
(since C++17) (until C++20) |
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template< class T > constexpr void destroy_at( T* p ); |
(since C++20) | |
If T
is not an array type, calls the destructor of the object pointed to by p, as if by p->~T().
If T
is an array type, the program is ill-formed(until C++20)recursively destroys elements of *p in order, as if by calling std::destroy(std::begin(*p), std::end(*p))(since C++20).
Contents |
[edit] Parameters
p | - | a pointer to the object to be destroyed |
[edit] Return value
(none)
[edit] Possible implementation
template<class T> constexpr void destroy_at(T* p) { if constexpr (std::is_array_v<T>) for (auto &elem : *p) (destroy_at)(std::addressof(elem)); else p->~T(); } // C++17 version: // template<class T> void destroy_at(T* p) { p->~T(); } |
[edit] Notes
destroy_at
deduces the type of object to be destroyed and hence avoids writing it explicitly in the destructor call.
When |
(since C++20) |
[edit] Example
The following example demonstrates how to use destroy_at
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)); for (int i = 0; i < 8; ++i) std::destroy_at(ptr + i); }
Output:
0 destructed 1 destructed 2 destructed 3 destructed 4 destructed 5 destructed 6 destructed 7 destructed
[edit] See also
(C++17) |
destroys a range of objects (function template) |
(C++17) |
destroys a number of objects in a range (function template) |
(C++20) |
creates an object at a given address (function template) |
(C++20) |
destroys an object at a given address (algorithm function object) |