std::allocation_result

 

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语言支持 类型支持（基本类型、 RTTI 、类型特征）     库功能特性测试宏 (C++20) 动态内存管理 程序工具 错误处理 协程支持 (C++20) 变参数函数 launder (C++17) initializer_list (C++11) source_location (C++20) 三路比较 (C++20) three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20) is_eqis_neqis_ltis_lteqis_gtis_gteq (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

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智能指针 unique_ptr (C++11) shared_ptr (C++11) weak_ptr (C++11) auto_ptr (C++17 前) owner_less (C++11) enable_shared_from_this (C++11) bad_weak_ptr (C++11) default_delete (C++11) out_ptr_t (C++23) inout_ptr_t (C++23) 分配器 allocator allocator_traits (C++11) allocation_result (C++23) allocate_at_least (C++23) allocator_arg_t (C++11) allocator_arg (C++11) uses_allocator (C++11) uses_allocator_construction_args (C++20) make_obj_using_allocator (C++20) uninitialized_construct_using_allocator (C++20) scoped_allocator_adaptor (C++11) pmr::polymorphic_allocator (C++17) 内存资源 pmr::memory_resource (C++17) pmr::get_default_resource (C++17) pmr::set_default_resource (C++17) pmr::new_delete_resource (C++17) pmr::null_memory_resource (C++17) pmr::synchronized_pool_resource (C++17) pmr::unsynchronized_pool_resource (C++17) pmr::monotonic_buffer_resource (C++17) pmr::pool_options (C++17) 未初始化存储 raw_storage_iterator (C++20 前) get_temporary_buffer (C++20 前) return_temporary_buffer (C++20 前)

未初始化内存算法 uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) destroy (C++17) destroy_at (C++17) uninitialized_copy_n (C++11) uninitialized_fill_n uninitialized_move_n (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17) destroy_n (C++17) construct_at (C++20) 受约束的未初始化内存算法 ranges::uninitialized_copy (C++20) ranges::uninitialized_fill (C++20) ranges::uninitialized_move (C++20) ranges::uninitialized_default_construct (C++20) ranges::uninitialized_value_construct (C++20) ranges::destroy (C++20) ranges::destroy_at (C++20) ranges::uninitialized_copy_n (C++20) ranges::uninitialized_fill_n (C++20) ranges::uninitialized_move_n (C++20) ranges::uninitialized_default_construct_n (C++20) ranges::uninitialized_value_construct_n (C++20) ranges::destroy_n (C++20) ranges::construct_at (C++20) 垃圾收集支持 declare_reachable (C++11)(C++23 前) undeclare_reachable (C++11)(C++23 前) declare_no_pointers (C++11)(C++23 前) undeclare_no_pointers (C++11)(C++23 前) pointer_safety (C++11)(C++23 前) get_pointer_safety (C++11)(C++23 前) 杂项 pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) C 库 malloc aligned_alloc (C++17) calloc realloc free 低层内存管理

 

定义于头文件 <memory>
template< class Pointer > struct allocation_result {     Pointer ptr;     std::size_t count; };		(C++23 起)

allocation_result 特化是适合的分配器 (Allocator) 类型的 allocate_at_least 成员函数（例如 std::allocator::allocate_at_least ）及 std::allocate_at_least 的返回类型。

allocation_result 的每个特化均无基类或 ptr 与 count 之外的声明成员，从而它适合聚合初始化及结构化绑定。

模板形参

Pointer

-

常为 std::allocator_traits<Alloc>::pointer ，其中 Alloc 为分配器 (Allocator) 类型

成员对象

ptr (C++23)	常用于 allocate_at_least 所分配的存储中首元素的地址 (公开成员对象)
count (C++23)	常用于 allocate_at_least 所分配的存储中的实际元素数 (公开成员对象)

参阅

allocate_at_least (C++23)	分配与请求的大小至少一样大的未初始化存储 (std::allocator<T> 的公开成员函数)
allocate_at_least (C++23)	经由分配器分配至少与请求的大小一样大的存储 (函数模板)