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

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.

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

#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';
}

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.

See also