Unpack compound values (pairs, tuples, arrays, objects, structs) into named variables in a single declaration. Eliminates index noise and .first/.second boilerplate.

pair / tuple pair / tuple

auto [x, y] = std::pair{1, 2};
auto [name, age] = std::tuple{"alice", 30};

map iteration

for (auto& [key, val] : my_map) {
    std::cout << key << ": " << val << '\n';
}

insert result

auto [it, inserted] = my_set.insert(42);
if (inserted) { /* new element */ }

plain aggregate struct

struct Point { int x, y; };
auto [px, py] = Point{3, 4};

Warning

C++ binding are copies by default. Use auto& in loops to avoid copying every element. Use const auto& when mutation isn't needed.

cpptricks

Structured Binding