voidify

 

C++

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Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

Technical specifications

Symbols index

External libraries

 

Algorithm library

Constrained algorithms and algorithms on ranges (C++20)
Constrained algorithms, e.g. ranges::copy, ranges::sort, ...
Non-modifying sequence operations     Batch operations for_each for_each_n (C++17) Search operations all_ofany_ofnone_of (C++11)(C++11)(C++11) countcount_if mismatch equal findfind_iffind_if_not (C++11) find_end find_first_of adjacent_find search search_n Modifying sequence operations Copy operations copycopy_if (C++11) copy_backward copy_n (C++11) move (C++11) move_backward (C++11) Swap operations swap iter_swap swap_ranges Transformation operations replacereplace_if transform replace_copyreplace_copy_if Generation operations fill fill_n generate generate_n Removing operations removeremove_if unique remove_copyremove_copy_if unique_copy Order-changing operations reverse reverse_copy rotate rotate_copy random_shuffleshuffle (until C++17)(C++11) shift_leftshift_right (C++20)(C++20) Sampling operations sample (C++17)	Sorting and related operations Partitioning operations partition partition_copy (C++11)     stable_partition is_partitioned (C++11)     partition_point (C++11) Sorting operations sort stable_sort partial_sort partial_sort_copy is_sorted (C++11) is_sorted_until (C++11) nth_element Binary search operations (on partitioned ranges) lower_bound upper_bound equal_range binary_search Set operations (on sorted ranges) includes set_union set_intersection          set_difference set_symmetric_difference Merge operations (on sorted ranges) merge inplace_merge Heap operations push_heap pop_heap make_heap sort_heap is_heap (C++11) is_heap_until (C++11) Minimum/maximum operations max min minmax (C++11) clamp (C++17) max_element min_element minmax_element (C++11) Lexicographical comparison operations lexicographical_compare lexicographical_compare_three_way (C++20) Permutation operations next_permutation prev_permutation is_permutation (C++11)	Execution policies (C++17) is_execution_policy (C++17) execution::seqexecution::parexecution::par_unseqexecution::unseq (C++17)(C++17)(C++17)(C++20) execution-policy (exposition only*)(C++26) execution::sequenced_policyexecution::parallel_policyexecution::parallel_unsequenced_policyexecution::parallel_unsequenced (C++17)(C++17)(C++17)(C++20) Numeric operations iota (C++11) inner_product      reduce (C++17) accumulate adjacent_difference transform_reduce (C++17) partial_sum inclusive_scan (C++17)     exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17) Specialized <memory> algorithms Specialized <random> algorithms ranges::generate_random (C++26) C library qsort bsearch

 

Specialized <memory> algorithms

Helper templates (exposition only*) voidify deref-move (C++17) nothrow-input-iteratornothrow-forward-iteratornothrow-bidirectional-iteratornothrow-random-access-iterator (C++20)(C++20)(C++26)(C++26) nothrow-sentinel-fornothrow-sized-sentinel-for (C++20)(C++26) nothrow-input-rangenothrow-forward-rangenothrow-bidirectional-rangenothrow-random-access-rangenothrow-sized-random-access-range (C++20)(C++20)(C++26)(C++26)(C++26) Object (batch) construction construct_at (C++20) uninitialized_copy uninitialized_fill uninitialized_move (C++17) uninitialized_copy_n (C++11) uninitialized_fill_n uninitialized_move_n (C++17) uninitialized_default_construct (C++17) uninitialized_default_construct_n (C++17)     uninitialized_value_construct (C++17) uninitialized_value_construct_n (C++17) ranges::construct_at (C++20) ranges::uninitialized_copy (C++20) ranges::uninitialized_fill (C++20) ranges::uninitialized_move (C++20) ranges::uninitialized_copy_n (C++20) ranges::uninitialized_fill_n (C++20) ranges::uninitialized_move_n (C++20) ranges::uninitialized_default_construct (C++20) ranges::uninitialized_default_construct_n (C++20) ranges::uninitialized_value_construct (C++20) ranges::uninitialized_value_construct_n (C++20) Object (batch) destruction destroy (C++17) destroy_n (C++17) destroy_at (C++17) ranges::destroy (C++20) ranges::destroy_n (C++20) ranges::destroy_at (C++20)

 

template< class T > void* /*voidify*/( T& obj ) noexcept;		(exposition only*) (constexpr since C++17)

Returns the address of obj (implicitly converted to void*).

Parameters

obj

-

the object whose address will be taken

Return value

&obj	(until C++11)
std::addressof(obj)	(since C++11)

Notes

This exposition-only function template is introduced by P0896R4. It is used to describe the effects of specialized <memory> algorithms. The result pointer is used as the placement-params of a placement new expression.

Initially, the return value was const_cast<void*>(static_cast<const volatile void*>(std::addressof(obj))), which breaks const-correctness. The explicit casts were removed by the resolution of LWG issue 3870, and the only conversion left is the implicit conversion to void*.

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 3870	C++98	the explicit casts broke const-correctness	removed these casts

See also

construct_at (C++20)	creates an object at a given address (function template & algorithm function object)
ranges::construct_at (C++20)
uninitialized_copy	copies a range of objects to an uninitialized area of memory (function template & algorithm function object)
ranges::uninitialized_copy (C++20)
uninitialized_copy_n (C++11)	copies a number of objects to an uninitialized area of memory (function template & algorithm function object)
ranges::uninitialized_copy_n (C++20)
uninitialized_fill	copies an object to an uninitialized area of memory, defined by a range (function template & algorithm function object)
ranges::uninitialized_fill (C++20)
uninitialized_fill_n	copies an object to an uninitialized area of memory, defined by a start and a count (function template & algorithm function object)
ranges::uninitialized_fill_n (C++20)
uninitialized_move (C++17)	moves a range of objects to an uninitialized area of memory (function template & algorithm function object)
ranges::uninitialized_move (C++20)
uninitialized_move_n (C++17)	moves a number of objects to an uninitialized area of memory (function template & algorithm function object)
ranges::uninitialized_move_n (C++20)

uninitialized_default_construct (C++17)	constructs objects by default-initialization in an uninitialized area of memory, defined by a range (function template & algorithm function object)
ranges::uninitialized_default_construct (C++20)
uninitialized_default_construct_n (C++17)	constructs objects by default-initialization in an uninitialized area of memory, defined by a start and a count (function template & algorithm function object)
ranges::uninitialized_default_construct_n (C++20)
uninitialized_value_construct (C++17)	constructs objects by value-initialization in an uninitialized area of memory, defined by a range (function template & algorithm function object)
ranges::uninitialized_value_construct (C++20)
uninitialized_value_construct_n (C++17)	constructs objects by value-initialization in an uninitialized area of memory, defined by a start and a count (function template & algorithm function object)
ranges::uninitialized_value_construct_n (C++20)