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

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

Allocates storage for n objects of type T using the underlying memory resource. Equivalent to return static_cast<T*>(resource()->allocate(n * sizeof(T), alignof(T)));.

Parameters

n - the number of objects to allocate storage for

Return value

A pointer to the allocated storage.

Exceptions

Throws std::bad_array_new_length if n > std::numeric_limits<std::size_t>::max() / sizeof(T); may also throw any exceptions thrown by the call to resource()->allocate.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3038 C++17 allocate might allocate storage of wrong size throws length_error instead
LWG 3237 C++17 the exception thrown by allocate was inconsistent with std::allocator::allocate made consistent

See also

(C++20)
allocate raw aligned memory from the underlying resource
(public member function)
(C++20)
allocates raw memory suitable for an object or an array
(public member function)
(C++20)
allocates and constructs an object
(public member function)
[static]
allocates uninitialized storage using the allocator
(public static member function of std::allocator_traits<Alloc>)
allocates memory
(public member function of std::pmr::memory_resource)

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