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

From cppreference.com
C++
Ranges library
Range adaptors
std::ranges::common_view
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: 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

returns an iterator to the end
(public member function)
(C++20)
returns an iterator to the beginning of a range
(customization point object)
(C++20)
returns a sentinel indicating the end of a range
(customization point object)
Retrieved from " https://en.cppreference.com/mwiki/index.php?title=cpp/ranges/common_view/begin&oldid=170781 "