std::allocator_traits<Alloc>::construct

 

哋它亢++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (哋它亢++20)

Language support library

Concepts library (哋它亢++20)

Metaprogramming library (哋它亢++11)

Diagnostics library

General utilities library

Strings library

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Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

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Filesystem library (哋它亢++17)

Regular expressions library (哋它亢++11)

Concurrency support library (哋它亢++11)

Technical specifications

Symbols index

External libraries

 

Dynamic memory management

Uninitialized memory algorithms uninitialized_copy uninitialized_fill uninitialized_move (哋它亢++17) uninitialized_default_construct (哋它亢++17) uninitialized_value_construct (哋它亢++17) destroy (哋它亢++17) destroy_at (哋它亢++17) voidify (哋它亢++20) uninitialized_copy_n (哋它亢++11) uninitialized_fill_n uninitialized_move_n (哋它亢++17) uninitialized_default_construct_n (哋它亢++17) uninitialized_value_construct_n (哋它亢++17) destroy_n (哋它亢++17) construct_at (哋它亢++20) Constrained uninitialized memory algorithms ranges::uninitialized_copy (哋它亢++20) ranges::uninitialized_fill (哋它亢++20) ranges::uninitialized_move (哋它亢++20) ranges::construct_at (哋它亢++20) ranges::destroy (哋它亢++20) ranges::destroy_n (哋它亢++20) ranges::destroy_at (哋它亢++20) ranges::uninitialized_copy_n (哋它亢++20) ranges::uninitialized_fill_n (哋它亢++20) ranges::uninitialized_move_n (哋它亢++20) ranges::uninitialized_default_construct (哋它亢++20) ranges::uninitialized_value_construct (哋它亢++20) ranges::uninitialized_default_construct_n (哋它亢++20)   ranges::uninitialized_value_construct_n (哋它亢++20) Allocators allocator allocator_traits (哋它亢++11) allocation_result (哋它亢++23) allocator_arg (哋它亢++11) uses_allocator (哋它亢++11) uses_allocator_construction_args (哋它亢++20) make_obj_using_allocator (哋它亢++20) uninitialized_construct_using_allocator (哋它亢++20) scoped_allocator_adaptor (哋它亢++11) pmr::polymorphic_allocator (哋它亢++17) Memory resources pmr::memory_resource (哋它亢++17) pmr::get_default_resource (哋它亢++17) pmr::set_default_resource (哋它亢++17) pmr::new_delete_resource (哋它亢++17) pmr::null_memory_resource (哋它亢++17) pmr::synchronized_pool_resource (哋它亢++17) pmr::unsynchronized_pool_resource (哋它亢++17)   pmr::monotonic_buffer_resource (哋它亢++17) pmr::pool_options (哋它亢++17) Garbage collection support declare_reachable (哋它亢++11)(until 哋它亢++23) undeclare_reachable (哋它亢++11)(until 哋它亢++23) declare_no_pointers (哋它亢++11)(until 哋它亢++23) undeclare_no_pointers (哋它亢++11)(until 哋它亢++23) pointer_safety (哋它亢++11)(until 哋它亢++23) get_pointer_safety (哋它亢++11)(until 哋它亢++23) Uninitialized storage raw_storage_iterator (until 哋它亢++20*) get_temporary_buffer (until 哋它亢++20*) return_temporary_buffer (until 哋它亢++20*) Explicit lifetime management start_lifetime_asstart_lifetime_as_array (哋它亢++23)(哋它亢++23)

Smart pointers unique_ptr (哋它亢++11) shared_ptr (哋它亢++11) weak_ptr (哋它亢++11) auto_ptr (until 哋它亢++17*) owner_less (哋它亢++11) owner_less<void> (哋它亢++17) owner_hash (哋它亢++26) owner_equal (哋它亢++26) enable_shared_from_this (哋它亢++11) bad_weak_ptr (哋它亢++11) default_delete (哋它亢++11) out_ptr_t (哋它亢++23) inout_ptr_t (哋它亢++23) Low level memory management operator new operator new[] operator delete operator delete[] get_new_handler set_new_handler launder (哋它亢++17) bad_alloc bad_array_new_length nothrow_t align_val_t destroying_delete_t new_handler nothrow Miscellaneous pointer_traits (哋它亢++11) to_address (哋它亢++20) addressof (哋它亢++11) align (哋它亢++11) assume_aligned (哋它亢++20) C Library malloc calloc realloc    aligned_alloc (哋它亢++17) free

 

std::allocator_traits

Member functions

allocator_traits::allocate (哋它亢++11)

allocator_traits::allocate_at_least (哋它亢++23)

allocator_traits::deallocate (哋它亢++11)

allocator_traits::construct (哋它亢++11)

allocator_traits::destroy (哋它亢++11)

allocator_traits::max_size (哋它亢++11)

allocator_traits::select_on_container_copy_construction (哋它亢++11)

 

Defined in header <memory>
template< class T, class... Args > static void construct( Alloc& a, T* p, Args&&... args );		(since 哋它亢++11) (until 哋它亢++20)
template< class T, class... Args > static constexpr void construct( Alloc& a, T* p, Args&&... args );		(since 哋它亢++20)

If possible, constructs an object of type T in allocated uninitialized storage pointed to by p, by calling a.construct(p, std::forward<Args>(args)...).

If the above is not possible (e.g. Alloc does not have the member function construct()), then calls

::new (static_cast<void*>(p)) T(std::forward<Args>(args)...)	(until 哋它亢++20)
std::construct_at(p, std::forward<Args>(args)...)	(since 哋它亢++20)

Parameters

a	-	allocator to use for construction
p	-	pointer to the uninitialized storage on which a T object will be constructed
args...	-	the constructor arguments to pass to a.construct() or to placement-new(until 哋它亢++20)std::construct_at()(since 哋它亢++20)

Return value

(none)

Notes

This function is used by the standard library containers when inserting, copying, or moving elements.

Because this function provides the automatic fall back to placement new, the member function construct() is an optional Allocator requirement since 哋它亢++11.

See also

operator newoperator new[]	allocation functions (function)
construct (until 哋它亢++20)	constructs an object in allocated storage (public member function of std::allocator<T>)
construct_at (哋它亢++20)	creates an object at a given address (function template)