tuple & ties

// Demonstration of tuple and ties on CM c++17
//
// g++-7 -std=c++17 tuple.cpp -o tuple
//
#include <iostream>
#include <string>
#include <tuple>

// function returns a tuple
// a neat way of having const as a string - number union
auto get_mark() {
    return std::make_tuple("mark", 42);
}
auto get_nick() {
    return std::make_tuple("nick", 45);
}

main()
{

// this time we list each item of the tuple returned
auto t = get_mark();
std::cout << std::get<0>(t) << std::endl;
std::cout << std::get<1>(t) << std::endl;

auto u = get_nick();
std::cout << std::get<0>(u) << std::endl;
std::cout << std::get<1>(u) << std::endl;

// here we use tie and return the tuple to the tie
std::string name;
int age;

std::tie(name, age) = get_mark();
std::cout << name << " is " << age << std::endl;
std::tie(name, age) = get_nick();
std::cout << name << " is " << age << std::endl;

// this time we auto return the tuple to name1 and age1
auto [name1, age1] = get_mark();
std::cout << name1 << " is " << age1 << std::endl;
auto [name2, age2] = get_nick();
std::cout << name2 << " is " << age2 << std::endl;

// this time we tie with the tuple and change its values
auto t4 = std::make_tuple(10, 20);
auto& [first, second] = t4;
first += 1;
second = 35;
std::cout << "value is now " << std::get<0>(t4) << " second is new " << std::get<1>(t4) << std::endl;

}