std::ranges::subrange

 

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Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
Range conversions
to (C++23)
Range primitives
range_size_trange_difference_t range_value_t	range_reference_trange_const_reference_trange_rvalue_reference_t   (C++23)	iterator_tconst_iterator_tsentinel_t (C++23)
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range    sized_range constant_range (C++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Factories
empty_viewviews::empty iota_viewviews::iota	single_viewviews::single basic_istream_viewviews::istream	repeat_viewviews::repeat (C++23)(C++23)
Adaptors
ref_view views::all_tviews::all common_viewviews::common owning_view views::counted reverse_viewviews::reverse zip_viewviews::zip (C++23)(C++23) as_const_viewviews::as_const (C++23)(C++23) as_rvalue_viewviews::as_rvalue (C++23)(C++23)	take_viewviews::take take_while_viewviews::take_while drop_viewviews::drop drop_while_viewviews::drop_while zip_transform_viewviews::zip_transform (C++23)(C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23)   cartesian_product_viewviews::cartesian_product (C++23)(C++23)	elements_viewviews::elements keys_viewviews::keys values_viewviews::values transform_viewviews::transform adjacent_viewviews::adjacent (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) stride_viewviews::stride (C++23)(C++23)	filter_viewviews::filter join_viewviews::join split_viewviews::split lazy_split_viewviews::lazy_split join_with_viewviews::join_with (C++23)(C++23) chunk_viewviews::chunk (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23)
Range adaptor objects
Range adaptor closure objects
Helper items
copyable-box	simple-view

 

std::ranges::subrange

Member functions

subrange::subrange (C++20)

subrange::operator PairLike (C++20)

Observers

subrange::begin (C++20)

subrange::end (C++20)

subrange::empty (C++20)

subrange::size (C++20)

Iterator operations

subrange::advance (C++20)

subrange::next (C++20)

subrange::prev (C++20)

Deduction guides

Non-member functions

get (C++20)

Helper types

subrange_kind (C++20)

tuple_size (C++20)

tuple_element (C++20)

 

Defined in header <ranges>
template<   std::input_or_output_iterator I,   std::sentinel_for<I> S = I,   ranges::subrange_kind K = std::sized_sentinel_for<S, I> ?     ranges::subrange_kind::sized : ranges::subrange_kind::unsized >   requires (K == ranges::subrange_kind::sized || !std::sized_sentinel_for<S, I>) class subrange : public ranges::view_interface<subrange<I, S, K>>		(since C++20)

The subrange class template combines together an iterator and a sentinel into a single view.

Additionally, the subrange is a sized_range whenever the final template parameter is subrange_kind​::​sized (which happens when std::sized_sentinel_for<S, I> is satisfied or when size is passed explicitly as a constructor argument). The size record is needed to be stored if and only if std::sized_sentinel_for<S, I> is false and K is subrange_kind::sized.

Member functions

(constructor) (C++20)	creates a new subrange (public member function)
operator PairLike (C++20)	converts the subrange to a pair-like type (public member function)
Observers
begin (C++20)	obtains the iterator (public member function)
end (C++20)	obtains the sentinel (public member function)
empty (C++20)	checks whether the subrange is empty (public member function)
size (C++20)	obtains the size of the subrange (public member function)
Iterator operations
advance (C++20)	advances the iterator by given distance (public member function)
prev (C++20)	obtains a copy of the subrange with its iterator decremented by a given distance (public member function)
next (C++20)	obtains a copy of the subrange with its iterator advanced by a given distance (public member function)
Inherited from std::ranges::view_interface
operator bool (C++20)	Returns whether the derived view is not empty. Provided if ranges::empty is applicable to it. (public member function of std::ranges::view_interface<D>)
data (C++20)	Gets the address of derived view's data. Provided if its iterator type satisfies contiguous_iterator. (public member function of std::ranges::view_interface<D>)
front (C++20)	Returns the first element in the derived view. Provided if it satisfies forward_range. (public member function of std::ranges::view_interface<D>)
back (C++20)	Returns the last element in the derived view. Provided if it satisfies bidirectional_range and common_range. (public member function of std::ranges::view_interface<D>)
operator[] (C++20)	Returns the nth element in the derived view. Provided if it satisfies random_access_range. (public member function of std::ranges::view_interface<D>)

Non-member functions

get(std::ranges::subrange) (C++20)

obtains iterator or sentinel from a std::ranges::subrange (function template)

Helper types

ranges::subrange_kind (C++20)	specifies whether a std::ranges::subrange models std::ranges::sized_range (enum)
std::tuple_size<std::ranges::subrange> (C++20)	obtains the number of components of a std::ranges::subrange (class template specialization)
std::tuple_element<std::ranges::subrange> (C++20)	obtains the type of the iterator or the sentinel of a std::ranges::subrange (class template specialization)

Helper templates

template<class I, class S, ranges::subrange_kind K> inline constexpr bool enable_borrowed_range<ranges::subrange<I, S, K>> = true;

This specialization of std::ranges::enable_borrowed_range makes subrange satisfy borrowed_range.

Example

Run this code

#include <iostream>
#include <map>
#include <ranges>
#include <string_view>
 
template <class V> void mutate(V& v) { v += 'A' - 'a'; }
 
template <class K, class V>
void mutate_map_values(std::multimap<K, V>& m, K k) {
    auto [first, last] = m.equal_range(k);
    for (auto& [_, v] : std::ranges::subrange(first, last)) {
        mutate(v);
    }
}
 
int main()
{
    auto print = [](std::string_view rem, auto const& mm) {
        std::cout << rem << "{ ";
        for (const auto& [k, v] : mm) std::cout << "{" << k << ",'" << v << "'} ";
        std::cout << "}\n";
    };
 
    std::multimap<int,char> mm{ {4,'a'}, {3,'-'}, {4,'b'}, {5,'-'}, {4,'c'} };
    print("Before: ", mm);
    mutate_map_values(mm, 4);
    print("After:  ", mm);
}

Output:

Before: { {3,'-'} {4,'a'} {4,'b'} {4,'c'} {5,'-'} }
After:  { {3,'-'} {4,'A'} {4,'B'} {4,'C'} {5,'-'} }

See also

ranges::view_interface (C++20)

helper class template for defining a view, using the curiously recurring template pattern (class template)