Thanks for C++ Weekly.

// what is a zip view?
#include <array>
#include <format>
#include <iostream>
#include <ranges>

int main() {
  std::array a1{1, 2, 3, 4, 5, 6};
  std::array a2{7, 8, 9, 10, 11};
  std::array a3{'a', 'b', 'c', 'd', 'e'};

  // zip returns a range of tuples of references to elements
  for (const auto& [e1, e2, e3] : std::ranges::views::zip(a1, a2, a3)) {
    std::cout << std::format("{}, {}, {}\n", e1, e2, e3);
  }
}

// case 1
for (const auto& [e1, e2, e3] : std::ranges::views::zip(a1, a2, a3))

// case 2
for (auto [e1, e2, e3] : std::ranges::views::zip(a1, a2, a3))

// case 3
for (auto&& [e1, e2, e3] : std::ranges::views::zip(a1, a2, a3))

In all three cases, the types of e1, e2, and e3 are int&, int&, and char&, respectively.

They are all mutable.

Their generated assembly code seem to be the same in release mode.

The case 1 is confusing because e1, e2, and e3 look like const references but actually they are not.

for (auto [e1, e2, e3] : std::ranges::views::zip(a1, a2, a3) | std::views::as_const)
// Their types are now const int&, const int&, and const char&, respectively.
// I have the same question here. Which one is better? (const auto&, auto, auto&&, etc.)

We usually use const auto& or auto& in range-based for loop but what is the best practice when using views?

Uh oh!

C++23's zip views #294

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