Building a Tuple in C++ – Tie, Make_Tuple and Forward_As_Tuple

How to Build a Tuple in C++?

Tuple construction in C++ enables you to create an object with multiple elements without having to define a new class. Tuples are used extensively in C++ programs, and come in three forms: tie, make_tuple, and forward_as_tuple.

tie()

The tie() function binds a C++ tuple to existing variables. It takes any number of arguments, which become the elements of the tuple. For example:

std::string a;
int b;
std::tie(a, b) = std::make_tuple("Hello", 42);

The above example binds string “Hello” to the existing string variable a, and binds the int value 42 to existing int variable b.

make_tuple()

The make_tuple() function creates a new tuple from arguments that you pass in. It is useful when you need to store multiple values, but don't want to create a new class. For example:

auto tuple = std::make_tuple("Hello", 42);

The above example creates a new tuple with two element: string “Hello” and int 42.

forward_as_tuple()

The forward_as_tuple() function is similar to make_tuple(), however, the function takes its arguments by reference. This can be useful when you need to keep references to values stored in the tuple. For example:

std::string s = "Hello";
int x = 42;
auto tuple = std::forward_as_tuple(s, x);

In this example, the values of s and x will remain valid even after the tuple goes out of scope since the tuple stores references to the original variables.

Tuple construction in C++ provides a simple way to combine multiple values in one object. You can use the tie(), make_tuple(), or forward_as_tuple() functions to create the tuple depending on your needs.