How to do it...

Applying a structured binding in order to assign multiple variables from one bundled structure is always one step. Let's first see how it was done before C++17. Then, we can have a look at multiple examples that show how we can do it in C++17:

• Accessing individual values of an std::pair: Imagine we have a mathematical function, divide_remainder, which accepts a dividend and a divisor parameter and returns the fraction of both as well as the remainder. It returns those values using an std::pair bundle:

 std::pair<int, int> divide_remainder(int dividend, int divisor);

Consider the following way of accessing the individual values of the resulting pair:

 const auto result (divide_remainder(16, 3));
 std::cout << "16 / 3 is " 
 << result.first << " with a remainder of " 
 << result.second << '\n';

Instead of doing it as shown in the preceding code snippet, we can now assign the individual values to individual variables with expressive names, which is much better to read:

 auto [fraction, remainder] = divide_remainder(16, 3);
 std::cout << "16 / 3 is " 
 << fraction << " with a remainder of " 
 << remainder << '\n';

• Structured bindings also work with std::tuple: Let's take the following example function, which gets us online stock information:

 std::tuple<std::string, 
 std::chrono::system_clock::time_point, unsigned>
 stock_info(const std::string &name);

Assigning its result to individual variables looks just like in the example before:

 const auto [name, valid_time, price] = stock_info("INTC");

• Structured bindings also work with custom structures: Let's assume a structure like the following:

 struct employee {
 unsigned id;
 std::string name;
 std::string role;
 unsigned salary;
 };

Now, we can access these members using structured bindings. We can even do that in a loop, assuming we have a whole vector of those:

 int main()
 {
 std::vector<employee> employees {
 /* Initialized from somewhere */};
 
 for (const auto &[id, name, role, salary] : employees) {
 std::cout << "Name: " << name
 << "Role: " << role
 << "Salary: " << salary << '\n';
 }
 }