std::allocation_result

 

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Defined in header <memory>
template< class Pointer, class SizeType > struct allocation_result {     Pointer ptr;     SizeType count; };		(since C++23)

allocation_result specializations are returned from the allocate_at_least member function of appropriate Allocator types (e.g. std::allocator::allocate_at_least) and std::allocator_traits::allocate_at_least.

Every specialization of allocation_result has no base classes or declared members other than ptr and count, thus it is suitable for aggregate initialization and structured binding.

Template parameters

Pointer	-	typically std::allocator_traits<Alloc>::pointer, where Alloc is an Allocator type
SizeType	-	typically std::allocator_traits<Alloc>::size_type, where Alloc is an Allocator type

Member objects

ptr (C++23)	typically used for the address of the first element in the storage allocated by allocate_at_least (public member object)
count (C++23)	typically used for the actual number of elements in the storage allocated by allocate_at_least (public member object)

Notes

Pointer and SizeType are a pointer to an object type and std::make_unsigned_t<std::ptrdiff_t> (which is almost always same as std::size_t) by default.

Feature-test macro	Value	Std	Feature
__cpp_lib_allocate_at_least	202106L	(C++23)

See also

allocate_at_least (C++23)	allocates uninitialized storage at least as large as requested size (public member function of std::allocator<T>)
allocate_at_least [static] (C++23)	allocates storage at least as large as the requested size via an allocator (public static member function of std::allocator_traits<Alloc>)