std::pmr::polymorphic_allocator<T>::allocate_object

 

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voidify (仅用于阐述*) 分配器 allocator allocator_traits (C++11) allocation_result (C++23) scoped_allocator_adaptor (C++11) pmr::polymorphic_allocator (C++17) 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) 未初始化内存算法 uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_copy_n (C++11) uninitialized_fill_n uninitialized_move_n (C++17) construct_at (C++20) uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) destroy (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17) destroy_n (C++17) destroy_at (C++17) 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_copy_n (C++20)  ranges::uninitialized_fill_n (C++20) ranges::uninitialized_move_n (C++20) ranges::construct_at (C++20) ranges::uninitialized_default_construct (C++20) ranges::uninitialized_value_construct (C++20) ranges::destroy (C++20) ranges::uninitialized_default_construct_n (C++20)  ranges::uninitialized_value_construct_n (C++20) ranges::destroy_n (C++20) ranges::destroy_at (C++20) 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::pool_options (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) 显式生存期管理 start_lifetime_as (C++23) start_lifetime_as_array (C++23) 用于复合类设计的类型 indirect (C++26) polymorphic (C++26) 未初始化存储(C++20 前) raw_storage_iterator (C++17 弃用) get_temporary_buffer (C++17 弃用) return_temporary_buffer (C++17 弃用) 垃圾收集器支持(C++23 前) declare_reachable (C++11)(C++23 前) declare_no_pointers (C++11)(C++23 前) pointer_safety (C++11)(C++23 前) undeclare_reachable (C++11)(C++23 前) undeclare_no_pointers (C++11)(C++23 前) get_pointer_safety (C++11)(C++23 前)

低层内存管理 operator newoperator new[] operator deleteoperator delete[] nothrow_t nothrow new_handler set_new_handler get_new_handler (C++11) bad_alloc bad_array_new_length (C++11) align_val_t (C++17) destroying_delete_t (C++20) launder (C++17) 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) owner_less<void> (C++17) owner_hash (C++26) owner_equal (C++26) 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) 杂项 pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) is_sufficiently_aligned (C++26) C 库 malloc calloc realloc free aligned_alloc (C++17)

 

std::pmr::polymorphic_allocator

成员函数

polymorphic_allocator::polymorphic_allocator

polymorphic_allocator::allocate

polymorphic_allocator::deallocate

polymorphic_allocator::construct

polymorphic_allocator::destroy (C++20/26*)

polymorphic_allocator::allocate_bytes (C++20)

polymorphic_allocator::deallocate_bytes (C++20)

polymorphic_allocator::allocate_object (C++20)

polymorphic_allocator::deallocate_object (C++20)

polymorphic_allocator::new_object (C++20)

polymorphic_allocator::delete_object (C++20)

polymorphic_allocator::select_on_container_copy_construction

polymorphic_allocator::resource

非成员函数

operator==operator!= (C++20 前)

 

template<class U > U* allocate_object(std::size_t n =1);		(C++20 起)

用底层内存资源分配 n 个 U 类型对象的存储。

若 std::numeric_limits<std::size_t>::max()/ sizeof(U)< n，则抛出 std::bad_array_new_length，否则等价于 returnstatic_cast<U*>(allocate_bytes(n * sizeof(U), alignof(U)));。

参数

n

-

要分配存储的对象数

返回值

指向分配的存储的指针。

注解

引入此函数是为了用于全特化分配器 std::pmr::polymorphic_allocator<>，但它可能在任何特化中都有用，作为避免从 std::pmr::polymorphic_allocator<T> 重绑定到 std::pmr::polymorphic_allocator<U> 的快捷方式。

因为不推导 U，调用此函数时必须提供它为模板实参。

异常

若 n >std::numeric_limits<std::size_t>::max()/ sizeof(U) 则抛出 std::bad_array_new_length；亦可能抛出任何调用 resource()->allocate 所抛的异常。

参阅

allocate_bytes (C++20)	从底层资源分配未处理的对齐内存 (公开成员函数)
new_object (C++20)	分配并创建对象 (公开成员函数)
allocate	分配内存 (公开成员函数)
allocate [静态]	用分配器分配未初始化的存储 (std::allocator_traits<Alloc> 的公开静态成员函数)
allocate	分配内存 (std::pmr::memory_resource 的公开成员函数)