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

T* allocate( std::size_t n );		(C++17 起) (C++20 前)
[[nodiscard]] T* allocate( std::size_t n );		(C++20 起)

用底层的 memory_resource 分配 n 个 T 类型对象的存储。等价于 return static_cast<T*>(resource()->allocate(n * sizeof(T), alignof(T))); 。

n

-

要分配存储的对象数

指向被分配存储的指针。

若 n > SIZE_MAX / sizeof(T) 则抛出 std::length_error ；亦可抛出调用 resource()->allocate 所抛的任何异常。

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)

成员函数
polymorphic_allocator::polymorphic_allocator
polymorphic_allocator::allocate
polymorphic_allocator::deallocate
polymorphic_allocator::construct
polymorphic_allocator::destroy
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!=