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

 

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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) voidify (C++20) 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) 受限未初始化内存算法 ranges::uninitialized_copy (C++20) ranges::uninitialized_fill (C++20) ranges::uninitialized_move (C++20) ranges::construct_at (C++20) ranges::destroy (C++20) ranges::destroy_n (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 (C++20) ranges::uninitialized_value_construct (C++20) ranges::uninitialized_default_construct_n (C++20)   ranges::uninitialized_value_construct_n (C++20) 分配器 allocator allocator_traits (C++11) allocation_result (C++23) 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) 垃圾收集支持 declare_reachable (C++11)(until C++23) undeclare_reachable (C++11)(until C++23) declare_no_pointers (C++11)(until C++23) undeclare_no_pointers (C++11)(until C++23) pointer_safety (C++11)(until C++23) get_pointer_safety (C++11)(until C++23) 未初始化存储 raw_storage_iterator (直到 C++20*) get_temporary_buffer (直到 C++20*) return_temporary_buffer (直到 C++20*) 显式生命周期管理 start_lifetime_asstart_lifetime_as_array (C++23)(C++23)

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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!= (until C++20)

 

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

使用底层内存资源为 n 个类型为 U 的对象分配存储空间。

如果 std::numeric_limits<std::size_t>::max() / sizeof(U) < n, 则抛出 std::bad_array_new_length, 否则等效于 return static_cast<U*>(allocate_bytes(n * sizeof(U), alignof(U)));.

参数

n

-

要为其分配存储空间的对象数量

返回值

指向已分配存储空间的指针。

说明

此函数是为与完全特化的分配器 std::pmr::polymorphic_allocator<> 一起使用而引入的，但它可能在任何专门化中都很有用，作为一种避免必须从 std::pmr::polymorphic_allocator<T> 重新绑定到 std::pmr::polymorphic_allocator<U> 的快捷方式。

由于 U 未被推断，因此在调用此函数时必须将其作为模板参数提供。

异常

如果 n > std::numeric_limits<std::size_t>::max() / sizeof(U); 则抛出 std::bad_array_new_length; 也可能是对 resource()->allocate.

参见

allocate_bytes (C++20)	从底层资源分配原始对齐内存 (公共成员函数)
new_object (C++20)	分配并构造一个对象 (公共成员函数)
allocate	分配内存 (公共成员函数)
allocate [静态]	使用分配器分配未初始化的存储空间 (std::allocator_traits<Alloc> 的公共静态成员函数)
allocate	分配内存 (std::pmr::memory_resource 的公共成员函数)