std:: allocation_result

Defined in header <memory>
template < class Pointer, class SizeType = std:: size_t > struct allocation_result ;		(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

Data members

Member name	Definition
ptr	a pointer of type Pointer which is typically used for the address of the first element in the storage allocated by allocate_at_least (public member object)
count	a value of type SizeType which is 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	202302L	(C++23)	Size-feedback in the Allocator interface

Example

This section is incomplete Reason: no example

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> )