| C++ Standard Library |
|---|
| Containers |
| C standard library |
In the C++ Standard Library, the algorithms library provides various functions that perform algorithmic operations on containers and other sequences, represented by Iterators.
The C++ standard provides some standard algorithms collected in the <algorithm> standard header. A handful of algorithms are also in the <numeric> header. All algorithms are in the std namespace. C++20 further introduces the <ranges> header with the std::ranges namespace, for algorithms over a range.
C++17 provides the ability for many algorithms to optionally take an execution policy, which may allow implementations to execute the algorithm in parallel (i.e. by using threads or SIMD instructions).
There are four different policy types, each indicating different semantics about the order in which element accesses are allowed to be observed relative to each other
sequenced_policy, which indicates that the execution of the algorithm must happen on the thread which invokes the function, and the order of element accesses should execute in sequence. It is equivalent to calling the function without an execution policyparallel_policy, which indicates that the execution of the algorithm may happen across multiple threads, however within each thread the order of element accesses are made in sequence (i.e. element accesses may not be done concurrently)parallel_unsequenced_policy, which indicates that the execution of the algorithm may happen across multiple threads, and element accesses do not have to be performed in order within the same threadunsequenced_policy, which indicates that the execution of the algorithm must happen on the thread which invokes the function, however the order of element accesses may be performed out of sequenceIt is up to the user to ensure that the operations performed by the function are thread safe when using policies which may execute across different threads.
C++20 adds versions of the algorithms defined in the <algorithm> header which operate on ranges rather than pairs of iterators.
The ranges versions of algorithm functions are scoped within the std::ranges namespace. They extend the functionality of the basic algorithms by allowing iterator-sentinel pairs to be used instead of requiring that both iterators be of the same type and also allowing interoperability with the objects provided by the ranges header without requiring the user to manually extract the iterators.
Checks if a given predicate evaluates to true for some amount of objects in the range, or returns the amount of objects that do
all_ofany_ofnone_ofcountcount_ifcontainsCompares two ranges for some property
mismatchequallexicographical_comparecontains_subrangestarts_withends_withis_permutationFinds the first or last position in a range where the subsequent elements satisfy some predicate
findfind_iffind_if_notfind_lastfind_last_iffind_last_if_notfind_endfind_first_ofadjacent_findsearchsearch_npartition_pointProvides Binary search operations on ranges. It is undefined behaviour to use these on ranges which are not sorted.
binary_searchupper_boundlower_boundequal_rangeFinds the maximum or minimum element in a range, as defined by some comparison predicate
max_elementmin_elementminmax_elementChecks if an entire range satisfies some property
is_partitionedis_sortedis_heapTransfers the elements from one range into another
copycopy_ifcopy_backwardmovemove_backwardreverse_copyrotate_copyunique_copysampleMoves the elements of a range in-place so the range is partitioned with respect to some property
uniqueremoveremove_ifpartitionpartition_copystable_partitionSorts or partially sorts a range in-place
sortpartial sortstable_sortnth_elementPopulates a given range without reading the values contained within
fillgenerateiotaTransforms each element of a given range in-place
for_eachtransformreplacereplace_ifclampChanges the order of elements within a range in-place
shuffleshift_leftshift_rightreverserotateProvides algorithms to create, insert, and remove elements from a max heap:
The standard library algorithms are found in <algorithm>.