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std::destroy_at(3) C++ Standard Libary std::destroy_at(3) NAME std::destroy_at - std::destroy_at Synopsis Defined in header <memory> template< class T > (since C++17) void destroy_at( T* p ); (until C++20) template< class T > (since C++20) constexpr void destroy_at( T* p ); 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). Parameters p - a pointer to the object to be destroyed Return value (none) 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(); } Notes destroy_at deduces the type of object to be destroyed and hence avoids writing it explicitly in the destructor call. When destroy_at is called in the evaluation of some constant expression e, the argument p must point to an object whose lifetime (since C++20) began within the evaluation of e. Example The following example demonstrates how to use destroy_at 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 con- struct 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 See also destroy destroys a range of objects (C++17) (function template) destroy_n destroys a number of objects in a range (C++17) (function template) construct_at creates an object at a given address (C++20) (function template) ranges::destroy_at destroys an object at a given address (C++20) (niebloid) http://cppreference.com 2022.07.31 std::destroy_at(3)
NAME | Synopsis | Parameters | Return value | Possible implementation | Notes | Example | Output: | See also
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