Constrained algorithms (since C++20)

 

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Ranges library (C++20)

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Symbols index

External libraries

 

Algorithm library

Constrained algorithms and algorithms on ranges (C++20)
Constrained algorithms, e.g. ranges::copy, ranges::sort, ...
Execution policies (C++17)
is_execution_policy (C++17)   execution::seqexecution::parexecution::par_unseqexecution::unseq (C++17)    (C++17)(C++17)(C++20)	execution::sequenced_policyexecution::parallel_policyexecution::parallel_unsequenced_policyexecution::parallel_unsequenced (C++17)(C++17)(C++17)(C++20)
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) C library qsort bsearch
Numeric operations
iota (C++11) inner_product adjacent_difference    accumulate reduce (C++17) transform_reduce (C++17)	partial_sum inclusive_scan (C++17)    exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
Operations on uninitialized memory
uninitialized_copy uninitialized_move (C++17)    uninitialized_fill uninitialized_copy_n (C++11) uninitialized_move_n (C++17) uninitialized_fill_n	destroy (C++17) destroy_n (C++17) destroy_at (C++17) construct_at (C++20)       uninitialized_default_construct (C++17) uninitialized_value_construct (C++17) uninitialized_default_construct_n (C++17) uninitialized_value_construct_n (C++17)

 

Constrained algorithms

All names in this menu belong to namespace std::ranges

Non-modifying sequence operations

all_ofany_ofnone_of for_each for_each_n    countcount_if adjacent_find mismatch equal lexicographical_compare    containscontains_subrange (C++23)(C++23) findfind_iffind_if_not find_lastfind_last_iffind_last_if_not (C++23)(C++23)(C++23)   find_end find_first_of search search_n starts_with (C++23) ends_with (C++23)

Modifying sequence operations

copycopy_if copy_n copy_backward    move move_backward shift_leftshift_right (C++23)(C++23)   fill fill_n generate generate_n    transform swap_ranges    shuffle sample removeremove_if replacereplace_if reverse rotate remove_copyremove_copy_if    unique replace_copyreplace_copy_if reverse_copy rotate_copy unique_copy

Partitioning operations

is_partitioned    partition_point    partition    partition_copy    stable_partition

Sorting operations

is_sorted is_sorted_until     sort stable_sort         partial_sort       nth_element partial_sort_copy

Binary search operations (on sorted ranges)

lower_bound         upper_bound         binary_search      equal_range

Set operations (on sorted ranges)

merge inplace_merge       set_difference set_intersection    set_union          includes set_symmetric_difference

Heap operations

is_heap is_heap_until       make_heap           sort_heap push_heap pop_heap

Minimum/maximum operations

max max_element         min min_element         minmax minmax_element     clamp

Permutation operations

is_permutation      next_permutation    prev_permutation

Fold operations

fold_left (C++23) fold_left_first (C++23)   fold_right (C++23) fold_right_last (C++23)   fold_left_with_iter (C++23) fold_left_first_with_iter (C++23)

Numeric operations iota (C++23)             Random number generation generate_random (C++26)

Operations on uninitialized storage

construct_at    destroy destroy_n destroy_at uninitialized_copy    uninitialized_move uninitialized_fill uninitialized_copy_n    uninitialized_move_n uninitialized_fill_n uninitialized_default_construct uninitialized_default_construct_n uninitialized_value_construct uninitialized_value_construct_n

Return types

in_fun_result in_in_result in_found_result    in_out_result in_in_out_result    in_out_out_result    min_max_result out_value_result (C++23) in_value_result (C++23)

 

C++20 provides constrained versions of most algorithms in the namespace std::ranges. In these algorithms, a range can be specified as either an iterator-sentinel pair or as a single range argument, and projections and pointer-to-member callables are supported. Additionally, the return types of most algorithms have been changed to return all potentially useful information computed during the execution of the algorithm.

Algorithm function objects

An algorithm function object (AFO), informally known as niebloid, is a customization point object (CPO) that is specified as one or more overloaded function templates. The name of these function templates designates the corresponding algorithm function object.

For an algorithm function object o, let S be the corresponding set of function templates. Then for any sequence of arguments args..., o(args...) is expression-equivalent to s(args...), where the result of name lookup for s is the overload set S.

The constrained algorithms in the namespace std::ranges are defined as algorithm function objects. As a result:

• Explicit template argument lists cannot be specified when calling any of them.
• None of them are visible to argument-dependent lookup.
• When any of them are found by normal unqualified lookup as the name to the left of the function-call operator, argument-dependent lookup is inhibited.

Constrained algorithms

Defined in header <algorithm>
Defined in namespace std::ranges
Non-modifying sequence operations
ranges::all_ofranges::any_ofranges::none_of (C++20)(C++20)(C++20)	checks if a predicate is true for all, any or none of the elements in a range (algorithm function object)
ranges::for_each (C++20)	applies a function to a range of elements (algorithm function object)
ranges::for_each_n (C++20)	applies a function object to the first N elements of a sequence (algorithm function object)
ranges::countranges::count_if (C++20)(C++20)	returns the number of elements satisfying specific criteria (algorithm function object)
ranges::mismatch (C++20)	finds the first position where two ranges differ (algorithm function object)
ranges::equal (C++20)	determines if two sets of elements are the same (algorithm function object)
ranges::lexicographical_compare (C++20)	returns true if one range is lexicographically less than another (algorithm function object)
ranges::findranges::find_ifranges::find_if_not (C++20)(C++20)(C++20)	finds the first element satisfying specific criteria (algorithm function object)
ranges::find_lastranges::find_last_ifranges::find_last_if_not (C++23)(C++23)(C++23)	finds the last element satisfying specific criteria (algorithm function object)
ranges::find_end (C++20)	finds the last sequence of elements in a certain range (algorithm function object)
ranges::find_first_of (C++20)	searches for any one of a set of elements (algorithm function object)
ranges::adjacent_find (C++20)	finds the first two adjacent items that are equal (or satisfy a given predicate) (algorithm function object)
ranges::search (C++20)	searches for the first occurrence of a range of elements (algorithm function object)
ranges::search_n (C++20)	searches for the first occurrence of a number consecutive copies of an element in a range (algorithm function object)
ranges::containsranges::contains_subrange (C++23)(C++23)	checks if the range contains the given element or subrange (algorithm function object)
ranges::starts_with (C++23)	checks whether a range starts with another range (algorithm function object)
ranges::ends_with (C++23)	checks whether a range ends with another range (algorithm function object)
Modifying sequence operations
ranges::copyranges::copy_if (C++20)(C++20)	copies a range of elements to a new location (algorithm function object)
ranges::copy_n (C++20)	copies a number of elements to a new location (algorithm function object)
ranges::copy_backward (C++20)	copies a range of elements in backwards order (algorithm function object)
ranges::move (C++20)	moves a range of elements to a new location (algorithm function object)
ranges::move_backward (C++20)	moves a range of elements to a new location in backwards order (algorithm function object)
ranges::fill (C++20)	assigns a range of elements a certain value (algorithm function object)
ranges::fill_n (C++20)	assigns a value to a number of elements (algorithm function object)
ranges::transform (C++20)	applies a function to a range of elements (algorithm function object)
ranges::generate (C++20)	saves the result of a function in a range (algorithm function object)
ranges::generate_n (C++20)	saves the result of N applications of a function (algorithm function object)
ranges::removeranges::remove_if (C++20)(C++20)	removes elements satisfying specific criteria (algorithm function object)
ranges::remove_copyranges::remove_copy_if (C++20)(C++20)	copies a range of elements omitting those that satisfy specific criteria (algorithm function object)
ranges::replaceranges::replace_if (C++20)(C++20)	replaces all values satisfying specific criteria with another value (algorithm function object)
ranges::replace_copyranges::replace_copy_if (C++20)(C++20)	copies a range, replacing elements satisfying specific criteria with another value (algorithm function object)
ranges::swap_ranges (C++20)	swaps two ranges of elements (algorithm function object)
ranges::reverse (C++20)	reverses the order of elements in a range (algorithm function object)
ranges::reverse_copy (C++20)	creates a copy of a range that is reversed (algorithm function object)
ranges::rotate (C++20)	rotates the order of elements in a range (algorithm function object)
ranges::rotate_copy (C++20)	copies and rotate a range of elements (algorithm function object)
ranges::shuffle (C++20)	randomly re-orders elements in a range (algorithm function object)
ranges::shift_leftranges::shift_right (C++23)	shifts elements in a range (algorithm function object)
ranges::sample (C++20)	selects N random elements from a sequence (algorithm function object)
ranges::unique (C++20)	removes consecutive duplicate elements in a range (algorithm function object)
ranges::unique_copy (C++20)	creates a copy of some range of elements that contains no consecutive duplicates (algorithm function object)
Partitioning operations
ranges::is_partitioned (C++20)	determines if the range is partitioned by the given predicate (algorithm function object)
ranges::partition (C++20)	divides a range of elements into two groups (algorithm function object)
ranges::partition_copy (C++20)	copies a range dividing the elements into two groups (algorithm function object)
ranges::stable_partition (C++20)	divides elements into two groups while preserving their relative order (algorithm function object)
ranges::partition_point (C++20)	locates the partition point of a partitioned range (algorithm function object)
Sorting operations
ranges::is_sorted (C++20)	checks whether a range is sorted into ascending order (algorithm function object)
ranges::is_sorted_until (C++20)	finds the largest sorted subrange (algorithm function object)
ranges::sort (C++20)	sorts a range into ascending order (algorithm function object)
ranges::partial_sort (C++20)	sorts the first N elements of a range (algorithm function object)
ranges::partial_sort_copy (C++20)	copies and partially sorts a range of elements (algorithm function object)
ranges::stable_sort (C++20)	sorts a range of elements while preserving order between equal elements (algorithm function object)
ranges::nth_element (C++20)	partially sorts the given range making sure that it is partitioned by the given element (algorithm function object)
Binary search operations (on sorted ranges)
ranges::lower_bound (C++20)	returns an iterator to the first element not less than the given value (algorithm function object)
ranges::upper_bound (C++20)	returns an iterator to the first element greater than a certain value (algorithm function object)
ranges::binary_search (C++20)	determines if an element exists in a partially-ordered range (algorithm function object)
ranges::equal_range (C++20)	returns range of elements matching a specific key (algorithm function object)
Set operations (on sorted ranges)
ranges::merge (C++20)	merges two sorted ranges (algorithm function object)
ranges::inplace_merge (C++20)	merges two ordered ranges in-place (algorithm function object)
ranges::includes (C++20)	returns true if one sequence is a subsequence of another (algorithm function object)
ranges::set_difference (C++20)	computes the difference between two sets (algorithm function object)
ranges::set_intersection (C++20)	computes the intersection of two sets (algorithm function object)
ranges::set_symmetric_difference (C++20)	computes the symmetric difference between two sets (algorithm function object)
ranges::set_union (C++20)	computes the union of two sets (algorithm function object)
Heap operations
ranges::is_heap (C++20)	checks if the given range is a max heap (algorithm function object)
ranges::is_heap_until (C++20)	finds the largest subrange that is a max heap (algorithm function object)
ranges::make_heap (C++20)	creates a max heap out of a range of elements (algorithm function object)
ranges::push_heap (C++20)	adds an element to a max heap (algorithm function object)
ranges::pop_heap (C++20)	removes the largest element from a max heap (algorithm function object)
ranges::sort_heap (C++20)	turns a max heap into a range of elements sorted in ascending order (algorithm function object)
Minimum/maximum operations
ranges::max (C++20)	returns the greater of the given values (algorithm function object)
ranges::max_element (C++20)	returns the largest element in a range (algorithm function object)
ranges::min (C++20)	returns the smaller of the given values (algorithm function object)
ranges::min_element (C++20)	returns the smallest element in a range (algorithm function object)
ranges::minmax (C++20)	returns the smaller and larger of two elements (algorithm function object)
ranges::minmax_element (C++20)	returns the smallest and the largest elements in a range (algorithm function object)
ranges::clamp (C++20)	clamps a value between a pair of boundary values (algorithm function object)
Permutation operations
ranges::is_permutation (C++20)	determines if a sequence is a permutation of another sequence (algorithm function object)
ranges::next_permutation (C++20)	generates the next greater lexicographic permutation of a range of elements (algorithm function object)
ranges::prev_permutation (C++20)	generates the next smaller lexicographic permutation of a range of elements (algorithm function object)

Constrained numeric operations

Defined in header <numeric>
Defined in namespace std::ranges
ranges::iota (C++23)	fills a range with successive increments of the starting value (algorithm function object)

Constrained fold operations

Defined in header <algorithm>
Defined in namespace std::ranges
ranges::fold_left (C++23)	left-folds a range of elements (algorithm function object)
ranges::fold_left_first (C++23)	left-folds a range of elements using the first element as an initial value (algorithm function object)
ranges::fold_right (C++23)	right-folds a range of elements (algorithm function object)
ranges::fold_right_last (C++23)	right-folds a range of elements using the last element as an initial value (algorithm function object)
ranges::fold_left_with_iter (C++23)	left-folds a range of elements, and returns a pair (iterator, value) (algorithm function object)
ranges::fold_left_first_with_iter (C++23)	left-folds a range of elements using the first element as an initial value, and returns a pair (iterator, optional) (algorithm function object)

Constrained uninitialized memory algorithms

Defined in header <memory>
Defined in namespace std::ranges
ranges::uninitialized_copy (C++20)	copies a range of objects to an uninitialized area of memory (algorithm function object)
ranges::uninitialized_copy_n (C++20)	copies a number of objects to an uninitialized area of memory (algorithm function object)
ranges::uninitialized_fill (C++20)	copies an object to an uninitialized area of memory, defined by a range (algorithm function object)
ranges::uninitialized_fill_n (C++20)	copies an object to an uninitialized area of memory, defined by a start and a count (algorithm function object)
ranges::uninitialized_move (C++20)	moves a range of objects to an uninitialized area of memory (algorithm function object)
ranges::uninitialized_move_n (C++20)	moves a number of objects to an uninitialized area of memory (algorithm function object)
ranges::uninitialized_default_construct (C++20)	constructs objects by default-initialization in an uninitialized area of memory, defined by a range (algorithm function object)
ranges::uninitialized_default_construct_n (C++20)	constructs objects by default-initialization in an uninitialized area of memory, defined by a start and count (algorithm function object)
ranges::uninitialized_value_construct (C++20)	constructs objects by value-initialization in an uninitialized area of memory, defined by a range (algorithm function object)
ranges::uninitialized_value_construct_n (C++20)	constructs objects by value-initialization in an uninitialized area of memory, defined by a start and a count (algorithm function object)
ranges::destroy (C++20)	destroys a range of objects (algorithm function object)
ranges::destroy_n (C++20)	destroys a number of objects in a range (algorithm function object)
ranges::destroy_at (C++20)	destroys an object at a given address (algorithm function object)
ranges::construct_at (C++20)	creates an object at a given address (algorithm function object)

Constrained random number algorithms

Defined in header <random>
Defined in namespace std::ranges
ranges::generate_random (C++26)	fills a range with random numbers from a uniform random bit generator (algorithm function object)

Return types

Defined in header <algorithm>
Defined in namespace std::ranges
ranges::in_fun_result (C++20)	provides a way to store an iterator and a function object as a single unit (class template)
ranges::in_in_result (C++20)	provides a way to store two iterators as a single unit (class template)
ranges::in_out_result (C++20)	provides a way to store two iterators as a single unit (class template)
ranges::in_in_out_result (C++20)	provides a way to store three iterators as a single unit (class template)
ranges::in_out_out_result (C++20)	provides a way to store three iterators as a single unit (class template)
ranges::min_max_result (C++20)	provides a way to store two objects or references of the same type as a single unit (class template)
ranges::in_found_result (C++20)	provides a way to store an iterator and a boolean flag as a single unit (class template)
ranges::in_value_result (C++23)	provides a way to store an iterator and a value as a single unit (class template)
ranges::out_value_result (C++23)	provides a way to store an iterator and a value as a single unit (class template)

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_algorithm_default_value_type	202403L	(C++26)	List-initialization for algorithms
__cpp_lib_ranges	201911L	(C++20)	Ranges library and constrained algorithms
__cpp_lib_ranges_contains	202207L	(C++23)	std::ranges::contains
__cpp_lib_ranges_find_last	202207L	(C++23)	std::ranges::find_last
__cpp_lib_ranges_fold	202207L	(C++23)	std::ranges fold algorithms
__cpp_lib_ranges_iota	202202L	(C++23)	std::ranges::iota
__cpp_lib_ranges_starts_ends_with	202106L	(C++23)	std::ranges::starts_with, std::ranges::ends_with
__cpp_lib_shift	201806L	(C++20)	std::shift_left, std::shift_right
	202202L	(C++23)	std::ranges::shift_left, std::ranges::shift_right
__cpp_lib_ranges_generate_random	202403L	(C++26)	std::ranges::generate_random

Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
P3136R1	C++20	niebloids were allowed to be specified as special entities other than function objects	required to be specified as function objects