std::allocator_traits::allocate

 

C++

Language

Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Dynamic memory management

Smart pointers unique_ptr (C++11) shared_ptr (C++11) weak_ptr (C++11) auto_ptr (until C++17) owner_less (C++11) enable_shared_from_this (C++11) bad_weak_ptr (C++11) default_delete (C++11) Allocators allocator allocator_traits (C++11) allocator_arg_t (C++11) allocator_arg (C++11) uses_allocator (C++11) scoped_allocator_adaptor (C++11) pmr::polymorphic_allocator (C++17) Memory resources 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)

Uninitialized storage uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) destroy (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) destroy_at (C++17) raw_storage_iterator (until C++20) get_temporary_buffer (until C++20) return_temporary_buffer (until C++20) Garbage collection support declare_reachable (C++11) undeclare_reachable (C++11) declare_no_pointers (C++11) undeclare_no_pointers (C++11) pointer_safety (C++11) get_pointer_safety (C++11) Miscellaneous pointer_traits (C++11) to_address (C++20) addressof (C++11) align (C++11) C Library malloc aligned_alloc (C++17) calloc realloc free Low level memory management

 

std::allocator_traits

Member functions

allocator_traits::allocate

allocator_traits::deallocate

allocator_traits::construct

allocator_traits::destroy

allocator_traits::max_size

allocator_traits::select_on_container_copy_construction

 

Defined in header <memory>
	(1)
static pointer allocate( Alloc& a, size_type n );			(since C++11) (until C++20)
[[nodiscard]] static pointer allocate( Alloc& a, size_type n );			(since C++20)
		(2)
static pointer allocate( Alloc& a, size_type n,                          const_void_pointer hint );				(since C++11) (until C++20)
[[nodiscard]] static pointer allocate( Alloc& a, size_type n,                                        const_void_pointer hint );				(since C++20)

Uses the allocator a to allocate n*sizeof(Alloc::value_type) bytes of uninitialized storage.

1) Calls a.allocate(n)

2) Additionally passes memory locality hint hint. Calls a.allocate(n, hint) if possible. If not possible (e.g. a has no two-argument member function allocate()), calls a.allocate(n)

Parameters

a	-	allocator to use
n	-	the number of objects to allocate storage for
hint	-	pointer to a nearby memory location

Return value

The pointer returned by the call to a.allocate(n)

See also

allocate

allocates uninitialized storage (public member function of std::allocator)