Preview: C++23 enumerate and zip

Two useful views for iterating over containers and enumerate and zip. These were introduced in C++23 and are defined in the <ranges> header.

`enumerate`

Listing 62 enumerate_example.cpp

#include <iostream>
#include <vector>
#include <ranges>

int main() {

    std::vector<double> powers{1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024};

    for (auto [index, value] : std::views::enumerate(powers)) {
        std::cout << index << " : " << value << std::endl;
    }
}

Note that enumerate returns a reference to the data even if you add const before the auto.

`zip`

Listing 63 zip_example.cpp

#include <iostream>
#include <vector>
#include <string>
#include <ranges>

int main() {

    std::vector<std::string> names{"A", "B", "C", "D", "E"};
    std::vector<int> values{1, 2, 3, 4, 5, 6};

    for (auto [v, n] : std::views::zip(names, values)) {
        std::cout << v << " : " << n << std::endl;
    }

}

In this example, the two containers are not the same length, so the looping ends when the first container runs out of objects.