std::pmr::polymorphic_allocator<T>::allocate

 

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voidify (僅作說明*) 未初始化記憶體演算法 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) 受約束的未初始化 記憶體演算法 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) C 庫 malloc calloc realloc aligned_alloc (C++17) free

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) 記憶體資源 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) 垃圾回收支援 declare_reachable (C++11)(直到 C++23) undeclare_reachable (C++11)(直到 C++23) declare_no_pointers (C++11)(直到 C++23) undeclare_no_pointers (C++11)(直到 C++23) pointer_safety (C++11)(直到 C++23) get_pointer_safety (C++11)(直到 C++23) 未初始化儲存 raw_storage_iterator (直到 C++20*) get_temporary_buffer (直到 C++20*) return_temporary_buffer (直到 C++20*) 顯式生命週期管理 start_lifetime_asstart_lifetime_as_array (C++23)(C++23)

智慧指標 unique_ptr (C++11) shared_ptr (C++11) weak_ptr (C++11) auto_ptr (直到 C++17*) 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) 低階記憶體 管理 operator new operator new[] operator delete operator delete[] get_new_handler (C++11) set_new_handler launder (C++17) bad_alloc bad_array_new_length (C++11) nothrow_t align_val_t (C++17) destroying_delete_t (C++20) new_handler nothrow 雜項 pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) assume_aligned (C++20) is_sufficiently_aligned (C++26)

 

std::pmr::polymorphic_allocator

成員函式

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

非成員函式

operator==operator!= (until C++20)

 

T* allocate( std::size_t n );		(C++17 起)

使用底層記憶體資源為 `T` 型別的 `n` 個物件分配儲存。等價於 return static_cast<T*>(resource()->allocate(n * sizeof(T), alignof(T)));。

引數

n

-

要分配儲存的物件數量

返回值

指向已分配儲存的指標。

異常

如果 n > std::numeric_limits<std::size_t>::max() / sizeof(T)，則丟擲 std::bad_array_new_length；也可能丟擲對 resource()->allocate 的呼叫所丟擲的任何異常。

缺陷報告

下列更改行為的缺陷報告追溯地應用於以前出版的 C++ 標準。

缺陷報告	應用於	釋出時的行為	正確的行為
LWG 3038	C++17	allocate 可能分配了錯誤大小的儲存空間	改為丟擲 length_error
LWG 3237	C++17	allocate 丟擲的異常與 std::allocator::allocate 不一致	已使其保持一致

參閱

allocate_bytes (C++20)	從底層資源分配原始對齊記憶體 (公共成員函式)
allocate_object (C++20)	分配適合物件或陣列的原始記憶體 (公共成員函式)
new_object (C++20)	分配並構造一個物件 (公共成員函式)
allocate [靜態]	使用分配器分配未初始化的儲存 (std::allocator_traits<Alloc> 的公共靜態成員函式)
allocate	分配記憶體 (std::pmr::memory_resource 的公共成員函式)