Ranges library (C++20)

 

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)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Ranges library

Range access begin cbegin   end cend rbegin crbegin   rend crend size ssize   data cdata empty

Range conversions std::from_range_t std::from_range (C++23)(C++23)     to (C++23)

Dangling iterator handling dangling borrowed_iterator_t borrowed_subrange_t

Range primitives
range_size_trange_difference_trange_value_t elements_of (C++23)	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (C++23)(C++23)	range_reference_trange_const_reference_trange_rvalue_reference_trange_common_reference_t (C++23)

Range concepts
range borrowed_range    sized_range	common_range view viewable_range	input_range output_range forward_range	bidirectional_range    random_access_range contiguous_range	constant_range (C++23)

Views
view_interface	subrange

Range factories
empty_viewviews::empty	single_viewviews::single	basic_istream_viewviews::istream	iota_viewviews::iota	repeat_viewviews::repeat (C++23)(C++23)

Range adaptors
views::all_tviews::all ref_view owning_view as_rvalue_viewviews::as_rvalue (C++23)(C++23)   filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while concat_viewviews::concat (C++26)(C++26)	drop_viewviews::drop drop_while_viewviews::drop_while join_viewviews::join join_with_viewviews::join_with (C++23)(C++23)   lazy_split_viewviews::lazy_split split_viewviews::split views::counted common_viewviews::common	reverse_viewviews::reverse as_const_viewviews::as_const (C++23)(C++23) elements_viewviews::elements keys_viewviews::keys values_viewviews::values enumerate_viewviews::enumerate (C++23)(C++23) zip_viewviews::zip (C++23)(C++23) zip_transform_viewviews::zip_transform (C++23)(C++23)	adjacent_viewviews::adjacent (C++23)(C++23) views::pairwise (C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23) views::pairwise_transform (C++23) chunk_viewviews::chunk (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23) stride_viewviews::stride (C++23)(C++23) cartesian_product_viewviews::cartesian_product (C++23)(C++23)

Range generators std::generator (C++23)

Range adaptor closure objects range_adaptor_closure (C++23)

Range adaptor objects

Helper items
copyable-box movable-box (until C++23)  (C++23)	simple-view non-propagating-cache

 

The ranges library provides components for dealing with ranges of elements, including a variety of view adapters.

Defined in header <ranges>
namespace std {     namespace views = ranges::views; }

The namespace alias std::views is provided as a shorthand for std::ranges::views.

Defined in header <ranges>
Defined in namespace std::ranges
Range access
ranges::begin (C++20)	returns an iterator to the beginning of a range (customization point object)
ranges::end (C++20)	returns a sentinel indicating the end of a range (customization point object)
ranges::rbegin (C++20)	returns a reverse iterator to a range (customization point object)
ranges::rend (C++20)	returns a reverse end iterator to a range (customization point object)
ranges::size (C++20)	returns an integer equal to the size of a range (customization point object)
ranges::empty (C++20)	checks whether a range is empty (customization point object)
ranges::data (C++20)	obtains a pointer to the beginning of a contiguous range (customization point object)
Range primitives
ranges::iterator_tranges::const_iterator_tranges::sentinel_tranges::const_sentinel_t (C++20)(C++23)(C++20)(C++23)	obtains iterator and sentinel types of a range (alias template)
Dangling iterator handling
ranges::dangling (C++20)	a placeholder type indicating that an iterator or a subrange should not be returned since it would be dangling (class)
ranges::borrowed_iterator_tranges::borrowed_subrange_t (C++20)	obtains iterator type or subrange type of a borrowed_range (alias template)
Range concepts
ranges::range (C++20)	specifies that a type is a range, that is, it provides a begin iterator and an end sentinel (concept)
ranges::borrowed_range (C++20)	specifies that a type is a range and iterators obtained from an expression of it can be safely returned without danger of dangling (concept)
ranges::sized_range (C++20)	specifies that a range knows its size in constant time (concept)
ranges::view (C++20)	specifies that a range is a view, that is, it has constant time copy/move/assignment (concept)
ranges::input_range (C++20)	specifies a range whose iterator type satisfies input_iterator (concept)
ranges::output_range (C++20)	specifies a range whose iterator type satisfies output_iterator (concept)
ranges::forward_range (C++20)	specifies a range whose iterator type satisfies forward_iterator (concept)
ranges::bidirectional_range (C++20)	specifies a range whose iterator type satisfies bidirectional_iterator (concept)
ranges::random_access_range (C++20)	specifies a range whose iterator type satisfies random_access_iterator (concept)
ranges::contiguous_range (C++20)	specifies a range whose iterator type satisfies contiguous_iterator (concept)
ranges::common_range (C++20)	specifies that a range has identical iterator and sentinel types (concept)
ranges::viewable_range (C++20)	specifies the requirements for a range to be safely convertible to a view (concept)
Views
ranges::view_interface (C++20)	helper class template for defining a view, using the curiously recurring template pattern (class template)
ranges::subrange (C++20)	combines an iterator-sentinel pair into a view (class template)

Range factories

Defined in header <ranges>
Defined in namespace std::ranges
ranges::empty_viewviews::empty (C++20)	an empty view with no elements (class template) (variable template)
ranges::single_viewviews::single (C++20)	a view that contains a single element of a specified value (class template) (customization point object)
ranges::iota_viewviews::iota (C++20)	a view consisting of a sequence generated by repeatedly incrementing an initial value (class template) (customization point object)
views::counted (C++20)	creates a subrange from an iterator and a count (customization point object)

Range adaptors

Range adaptors accept viewable_range as their first arguments and return a view.

If an adaptor takes only one argument, it can also be called using the pipe operator: if C is a range adaptor object and R is a viewable_range, these two expressions are equivalent:

C(R)
R | C

Unary range adaptors can also be chained to produce another range adaptor: if C and D are range adaptor objects and R is a viewable_range, then C | D is also a range adaptor object, and these two expressions are equivalent:

R | C | D   // (R | C) | D
R | (C | D)

If an adaptor takes multiple arguments, these forms are equivalent:

adaptor(range, args...)
adaptor(args...)(range)
range | adaptor(args...)

In this case, adaptor(args...) is a unary range adaptor object.

Defined in header <ranges>
Defined in namespace std::ranges
views::all_tviews::all (C++20)	a view that includes all elements of a range (alias template) (range adaptor object)
ranges::ref_view (C++20)	a view of the elements of some other range (class template)
ranges::filter_viewviews::filter (C++20)	a view that consists of the elements of a range that satisfies a predicate (class template) (range adaptor object)
ranges::transform_viewviews::transform (C++20)	a view of a sequence that applies a transformation function to each element (class template) (range adaptor object)
ranges::take_viewviews::take (C++20)	a view consisting of the first N elements of another view (class template) (range adaptor object)
ranges::take_while_viewviews::take_while (C++20)	a view consisting of the initial elements of another view, until the first element on which a predicate returns false (class template) (range adaptor object)
ranges::drop_viewviews::drop (C++20)	a view consisting of elements of another view, skipping the first N elements (class template) (range adaptor object)
ranges::drop_while_viewviews::drop_while (C++20)	a view consisting of the elements of another view, skipping the initial subsequence of elements until the first element where the predicate returns false (class template) (range adaptor object)
ranges::join_viewviews::join (C++20)	a view consisting of the sequence obtained from flattening a view of ranges (class template) (range adaptor object)
ranges::split_viewviews::split (C++20)	a view over the subranges obtained from splitting another view using a delimiter (class template) (range adaptor object)
ranges::common_viewviews::common (C++20)	converts a view into a common_range (class template) (range adaptor object)
ranges::reverse_viewviews::reverse (C++20)	a view that iterates over the elements of another bidirectional view in reverse order (class template) (range adaptor object)
ranges::basic_istream_viewviews::istream (C++20)	a view consisting of the elements obtained by successive application of operator>> on the associated input stream (class template) (customization point object)
ranges::elements_viewviews::elements (C++20)	takes a view consisting of tuple-like values and a number N and produces a view of Nth element of each tuple (class template) (range adaptor object)
ranges::keys_viewviews::keys (C++20)	takes a view consisting of pair-like values and produces a view of the first elements of each pair (class template) (range adaptor object)
ranges::values_viewviews::values (C++20)	takes a view consisting of pair-like values and produces a view of the second elements of each pair (class template) (range adaptor object)

Some range adaptors wrap their element or function object with the semiregular wrapper.

Helper concepts

Following exposition-only concepts are used for several types, but they are not parts of the interface of standard library.

template<class R>   concept __SimpleView =                         // exposition only     ranges::view<R> && ranges::range<const R> &&     std::same_as<std::ranges::iterator_t<R>, std::ranges::iterator_t<const R>> &&     std::same_as<std::ranges::sentinel_t<R>, std::ranges::sentinel_t<const R>>;
template<class T, class U>   concept __NotSameAs =                          // exposition only     !std::same_as<std::remove_cvref_t<T>, std::remove_cvref_t<U>>;

Example

Run this code

#include <vector>
#include <ranges>
#include <iostream>
 
int main()
{
    std::vector<int> ints{0,1,2,3,4,5};
    auto even = [](int i){ return 0 == i % 2; };
    auto square = [](int i) { return i * i; };
 
    for (int i : ints | std::views::filter(even) | std::views::transform(square)) {
        std::cout << i << ' ';
    }
}

Output:

0 4 16