<tuple> provides std::tuple<T1, T2, ...>, a heterogeneous fixed-size container holding values of different types. Use std::get<I>(t) to access by index or std::get<T>(t) to access by type. C++17 structured bindings (auto [x, y] = tuple) make tuples convenient.

Tuples are useful for returning multiple values from a function without defining a struct.

This example returns multiple values of different types from a function via tuple, using structured bindings to unpack them.

// compile: g++ -std=c++17 -o tupleexample tupleexample.cpp
// run: ./tupleexample
// description: tuple creation and unpacking
 
#include <tuple>
#include <iostream>
#include <string>
 
std::tuple<int, double, std::string> fetch_data() {
    return {42, 3.14, "hello"};
}
 
int main() {
    auto [i, d, s] = fetch_data();
    std::cout << "int: " << i << ", double: " << d << ", string: " << s << "\n";
 
    return 0;
}