std::ranges::concat_view<Views...>::begin

 

C++

Compiler support

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

 

std::ranges::concat_view

Member functions

concat_view::concat_view

concat_view::begin

concat_view::end

concat_view::size

Deduction guides

Iterator

Member functions

concat_view::iterator::iterator

concat_view::iterator::operator*

concat_view::iterator::operator[]

concat_view::iterator::operator++ concat_view::iterator::operator++(int) concat_view::iterator::operator-- concat_view::iterator::operator--(int) concat_view::iterator::operator+= concat_view::iterator::operator-=

concat_view::iterator::satisfy concat_view::iterator::prev concat_view::iterator::advance-fwd concat_view::iterator::advance-bwd

Non-member functions

operator==(concat_view::iterator) operator<(concat_view::iterator) operator>(concat_view::iterator) operator<=(concat_view::iterator) operator>=(concat_view::iterator) operator<=>(concat_view::iterator)

operator+(concat_view::iterator) operator-(concat_view::iterator)

iter_move(concat_view::iterator)

iter_swap(concat_view::iterator)

 

constexpr /*iterator*/<false> begin()     requires (!(/*simple-view*/<Views> && ...));	(1)	(since C++26)
constexpr /*iterator*/<true> begin() const     requires (ranges::range<const Views> && ...) &&                  /*concatable*/<const Views...>;	(2)	(since C++26)

Returns an iterator to the beginning of the concat_view.

1) Equivalent to iterator <false> it(this, std::in_place_index<0>,
                   ranges::begin(std::get<0>(views_ )));
it.template satisfy <0>();
return it;.

2) Equivalent to iterator <true> it(this, std::in_place_index<0>,
                  ranges::begin(std::get<0>(views_ )));
it.template satisfy <0>();
return it;.

Return value

As specified above.

Example

The preliminary version can be checked out on Compiler Explorer.

Run this code

#include <ranges>
#include <string_view>
using namespace std::literals;
 
int main()
{
    static constexpr auto c = {"🐱", "🐶"};
    static constexpr auto a = {"🤡"sv};
    static constexpr auto t = {"💚"sv};
    static constexpr auto cat{std::views::concat(c, a, t)};
    static_assert(*cat.begin() == "\U0001F431" and
                  cat.begin()[1] == "🐶" and
                  *(cat.begin() + 2) == "\N{CLOWN FACE}");
}

See also

end	returns an iterator or a sentinel to the end (public member function)
ranges::begin (C++20)	returns an iterator to the beginning of a range (customization point object)