std::ranges::views::values,std::ranges::values_view(3)

NAME
std::ranges::views::values,std::ranges::values_view - std::ranges::views::values,std::ranges::values_view

Synopsis
   Defined in header <ranges>
   template< class R > (1) (since C++20)
   using values_view = ranges::elements_view<R, 1>;
   namespace views {
       inline constexpr auto values = ranges::elements<1>; (2) (since C++20)
   }
   Takes a view of tuple-like values (e.g. std::tuple or std::pair), and produces a
   view with a value-type of the second element of the adapted view's value-type.
   1) An alias for ranges::elements_view<R, 1>.
   2) RangeAdaptorObject (and also RangeAdaptorClosureObject). The expression
   views::values(e) is expression-equivalent to
   values_view<views::all_t<decltype((e))>>{e} for any suitable subexpression e.

Notes
   values_view can be useful for extracting values from associative containers, e.g.
 std::map<int, std::string> map{{1, "alpha"}, {2, "beta"}};
 for (auto const& value : std::views::values(map))
     std::cout << value << ' ';
 // prints: alpha beta

Example
// Run this code
 #include <iostream>
 #include <map>
 #include <ranges>
 int main()
 {
     const auto list = {std::pair{1, 11.1}, {2, 22.2}, {3, 33.3}};
     std::cout << "pair::second values in the list: ";
     for (double value : list | std::views::values)
         std::cout << value << ' ';
     std::map<char, int> map{{'A', 1}, {'B', 2}, {'C', 3}, {'D', 4}, {'E', 5}};
     auto odd = [](int x) { return 0 != (x & 1); };
     std::cout << "\nodd values in the map: ";
     for (int value : map | std::views::values | std::views::filter(odd))
         std::cout << value << ' ';
     std::cout << '\n';
 }

Output:
 pair::second values in the list: 11.1 22.2 33.3
 odd values in the map: 1 3 5
   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 3563 C++20 keys_view is unable to participate in CTAD views::all_t removed
                       due to its use of views::all_t

See also
   ranges::keys_view takes a view consisting of pair-like values and produces a
   views::keys view of the first elements of each pair
   (C++20) (class template) (range adaptor object)
   ranges::elements_view takes a view consisting of tuple-like values and a number N
   views::elements and produces a view of N^th element of each tuple
   (C++20) (class template) (range adaptor object)
   slice BLAS-like slice of a valarray: starting index, length, stride
                        (class)