std::ranges::common_view<V>::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::common_view

Member functions

common_view::common_view

common_view::base

common_view::begin

common_view::end

common_view::size

Deduction guides

 

constexpr auto begin() requires (!__simple_view<V>);	(1)	(since C++20)
constexpr auto begin() const requires range<const V>;	(2)	(since C++20)

1) Returns an iterator to the first element of the common_view, that is:

• ranges::begin(base_), if both ranges::random_access_range<V> and ranges::sized_range<V> are satisfied,
• std::common_iterator<ranges::iterator_t<V>, ranges::sentinel_t<V>>(ranges::begin(base_)) otherwise.

Here base_ (the name is for exposition only purposes) is the underlying view.

2) Same as (1), but V is const-qualified.

Parameters

(none)

Return value

An iterator to the beginning of the underlying view.

Example

Run this code

#include <iostream>
#include <numeric>
#include <ranges>
#include <string_view>
 
int main()
{
    constexpr auto common = std::views::iota(1)
                          | std::views::take(3)
                          | std::views::common
                          ;
 
    for (int i{}; int e : common)
        std::cout << (i++ ? " + " : "") << e;
 
    std::cout << " = " << std::accumulate(common.begin(), common.end(), 0) << '\n';
}

Output:

1 + 2 + 3 = 6

Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
LWG 4012	C++20	non-const overload missed simple-view check	added

See also

end	returns an iterator to the end (public member function)
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)