NAME¶

std::ranges::common_view::begin - std::ranges::common_view::begin

Synopsis¶

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