C# Tuples

Summary: in this tutorial, you’ll learn how to use C# tuples to represent a set of values as a single unit.

Introduction to the C# tuples

A tuple allows you to represent a set of values as a single unit. The type of tuples is System.ValueTuple.

Creating tuples & accessing elements

The following shows how to create a new tuple type:

using static System.Console;

var person = ("John Doe", 22);
WriteLine(person);Code language: C# (cs)

Output:

(John Doe, 22)Code language: C# (cs)

In this example, we define a tuple named person with two fields. The first field is a string that represents the person’s name and the second field is an integer that represents the person’s age.

To access a field, you use the dot syntax:

tuple.fieldCode language: C# (cs)

Because fields of the person tuple have no names, C# assigns default field names to them as Item1, Item2, etc. For example:

using static System.Console;

var person = ("John Doe", 22);

WriteLine($"Name: {person.Item1}, Age: {person.Item2}");Code language: C# (cs)

Output:

Name: John Doe, Age: 22Code language: C# (cs)

To assign names to the fields of the tuple, you can use the following syntax:

using static System.Console;

var person = (Name: "John Doe", Age: 22) ;

WriteLine($"Name: {person.Name}, Age: {person.Age}");Code language: C# (cs)

In this example, we assign names to the fields of the person tuple and access their values via the field names.

Deconstructing tuple elements

Deconstructing a tuple means assigning elements of the tuple to multiple variables. To deconstruct elements of a tuple, you use the = operator. For example:

using static System.Console;

var point = (10,20);

var (x,y) = point; // deconstructing a tuple

WriteLine($"x:{x}, y:{y}");Code language: C# (cs)

Output:

x:10, y:20Code language: C# (cs)

In this example, we assign the first and second elements of a tuple to the x and y variables.

You can also specify the types of variables explicitly when deconstructing a tuple:

using static System.Console;

var point = (10,20);

(int x,int y) = point; // deconstructing a tuple

WriteLine($"x:{x}, y:{y}");Code language: C# (cs)

Returning tuples

Tuples are useful when you want to return multiple values from a method. For example:

using static System.Console;

static (int sum, int product) Calculate(int x, int y)
{
    return (x + y, x * y);
}

var result = Calculate(20, 30);

WriteLine(result.sum);     // output: 50
WriteLine(result.product); // output: 600Code language: C# (cs)

In this example, the method Calculate returns a named tuple with two elements: sum and product. When calling the method, we can assign the returned tuple to a variable result and access its elements using dot notation.

Note that you can deconstruct the tuple returned by the method like this:

using static System.Console;

static (int sum, int product) Calculate(int x, int y)
{
    return (x + y, x * y);
}

var (sum,product) = Calculate(20, 30);

WriteLine(sum);     // output: 50
WriteLine(product); // output: 600Code language: C# (cs)

Comparing Tuples

Tuples support the == and != operators. Two tuples are comparable when they comply with the following conditions:

• Both tuples have the same number of elements.
• The corresponding tuple elements are comparable using the == and != operators.

For example, the following example will result in an error because the number of elements is different:

var point2D = (10,20);
var point3D = (10,20,30);

point2D == point3D; // ERRORCode language: C# (cs)

The following example demonstrates that two tuples are equal:

using static System.Console;

var point1 = (10,20,30);
var point2 = (10, 20,30);

var result = point1 == point2;
WriteLine($"Result:{result}");Code language: C# (cs)

Output:

Result:TrueCode language: C# (cs)

System.ValueTuple vs. System.Tuple

So far, you have learned the tuples that belong to the System.ValueTuple type. They are completely different from tuples backed by the System.Tuple types.

The following table illustrates the main differences:

Summary

• Use a tuple to represent a set of values as a single variable.
• Do use tuples to make your code more readable and expressive.