Tuples are lightweight data structures that contain multiple fields to represent the data members. The fields are not validated, and you cannot define your own methods.
NOTE: Tuples were available before C# 7.0, but they were inefficient and had no language support. This meant that tuple elements could only be referenced as
Item1,Item2and so on. C# 7.0 introduces language support for tuples, which enables semantic names for the fields of a tuple using new more efficient tuple types.
You can create a tuple by assigning a value to each named member:
The namedLetters tuple contains fields referred to as Alpha and Beta. Those names exist only at compile time and are not preserved at runtime (when inspecting the tuple using reflection, for example).
In a tuple assignment, you can also specify the names of the fields on the right-hand side of the assignment:
If you don't specify any names for the tuple members, the member names are inferred from the variable names on the right side of any initialization:
You can specify names for the fields on both the left and right-hand side of the assignment. In that case, the variable uses the names on the left side of the assignment.
Tuples are most useful as return types for private and internal methods. Tuples provide a simple syntax for those methods to return multiple discrete values. Creating a tuple is more efficient and more productive that creating a class or struct. It has a simpler, lightweight syntax to define a data structure that carries more than one value. The example method below returns the minimum and maximum values found in a sequence of integers. Try the following code:
There may be times when you want to unpackage the members of a tuple that were returned from a method. You can do that by declaring separate variables for each of the values in the tuple. This is called deconstructing the tuple. Add the following code in your browser to try it:
(int max, int min) = Range(numbers);
Console.WriteLine(max);
Console.WriteLine(min);As you work with tuples, you'll often find that you don't use all of the members of a tuple result. When that happens, you can discard one or more of the returned values by using _ in place of a variable. Try the following code yourself:
(int maxValue, _) = Range(numbers);
Console.WriteLine(max);You can explore more in the tuples article on docs.microsoft.com.