Returning two values, Tuple vs 'out' vs 'struct'

Question

Consider a function which returns two values. We can write:

// Using out:
string MyFunction(string input, out int count)

// Using Tuple class:
Tuple

        

Answer 1

Adding to the previous answers, C# 7 brings value type tuples, unlike System.Tuple that is a reference type and also offer improved semantics.

You can still leave them unnamed and use the .Item* syntax:

(string, string, int) getPerson()
{
    return ("John", "Doe", 42);
}

var person = getPerson();
person.Item1; //John
person.Item2; //Doe
person.Item3;   //42

But what is really powerful about this new feature is the ability to have named tuples. So we could rewrite the above like this:

(string FirstName, string LastName, int Age) getPerson()
{
    return ("John", "Doe", 42);
}

var person = getPerson();
person.FirstName; //John
person.LastName; //Doe
person.Age;   //42

Destructuring is also supported:

(string firstName, string lastName, int age) = getPerson()