std::ranges::views::values, std::ranges::values_view

template<class R>
using values_view = ranges::elements_view<R, 1>;

namespace views {
    inline constexpr auto values = ranges::elements<1>;
}

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.

Expression-equivalent

Expression e is expression-equivalent to expression f, if.

• e and f have the same effects, and
• either both are constant subexpressions or else neither is a constant subexpression, and
• either both are potentially-throwing or else neither is potentially-throwing (i.e. noexcept(e) == noexcept(f)).

Notes

values_view can be useful for extracting values from associative containers, e.g. for (auto const& value : std::views::values(map)) { /*...*/ }.

Example

#include <iostream>
#include <ranges>
#include <map>
 
int main()
{
    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 << "Odd values in the map: ";
    for (int value : map | std::views::values | std::views::filter(odd))
        std::cout << value << ' ';
}

Odd values in the map: 1 3 5

Defect reports

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

See also