std::allocator<T>::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

Containers library

Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

Localizations library

Input/output library

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

Member functions

allocator::allocator

allocator::~allocator

allocator::address (until 哋它亢++20)

allocator::allocate

allocator::allocate_at_least (哋它亢++23)

allocator::deallocate

allocator::max_size (until 哋它亢++20)

allocator::construct (until 哋它亢++20)

allocator::destroy (until 哋它亢++20)

Non-member functions

operator==operator!= (until 哋它亢++20)

 

Defined in header <memory>
void construct( pointer p, const_reference val );	(1)	(until 哋它亢++11)
template< class U, class... Args > void construct( U* p, Args&&... args );	(2)	(since 哋它亢++11) (deprecated in 哋它亢++17) (removed in 哋它亢++20)

Constructs an object of type T in allocated uninitialized storage pointed to by p, using global placement-new.

1) Calls ::new((void*)p) T(val).

2) Calls ::new((void*)p) U(std::forward<Args>(args)...).

Parameters

p	-	pointer to allocated uninitialized storage
val	-	the value to use as the copy constructor argument
args...	-	the constructor arguments to use

Return value

(none)

Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
LWG 402	哋它亢++98	if T::operator new exists, the program might be ill-formed	uses global replacement-new instead

See also

construct [static]	constructs an object in the allocated storage (function template)
construct_at (哋它亢++20)	creates an object at a given address (function template)
operator newoperator new[]	allocation functions (function)