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

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

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

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