How to declare a tuple in C#?

A tuple in C# is a data structure that can hold multiple values of different types. Tuples are useful when you need to return multiple values from a method or group related data together without creating a separate class.

C# provides two main ways to declare tuples: the classic Tuple<T1, T2> class and the newer value tuples introduced in C# 7.0 with cleaner syntax.

Syntax

Classic tuple syntax −

Tuple<int, string> tuple = new Tuple<int, string>(value1, value2);

Value tuple syntax (C# 7.0+) −

(int, string) tuple = (value1, value2);
// or with named elements
(int id, string name) tuple = (value1, value2);

Using Classic Tuple Declaration

The traditional way uses the Tuple<T1, T2> class where you access elements using Item1, Item2, etc. −

using System;

class Program {
   static void Main(string[] args) {
      Tuple<int, string> tuple = new Tuple<int, string>(50, "Tom");
      
      Console.WriteLine("First item: " + tuple.Item1);
      Console.WriteLine("Second item: " + tuple.Item2);
      
      if (tuple.Item1 == 50) {
         Console.WriteLine("ID matches: " + tuple.Item1);
      }
      
      if (tuple.Item2 == "Tom") {
         Console.WriteLine("Name matches: " + tuple.Item2);
      }
   }
}

The output of the above code is −

First item: 50
Second item: Tom
ID matches: 50
Name matches: Tom

Using Value Tuples (C# 7.0+)

Value tuples provide a more readable syntax and better performance. You can use unnamed or named elements −

using System;

class Program {
   static void Main(string[] args) {
      // Unnamed value tuple
      (int, string) tuple1 = (25, "Alice");
      Console.WriteLine($"Unnamed: {tuple1.Item1}, {tuple1.Item2}");
      
      // Named value tuple
      (int id, string name) tuple2 = (30, "Bob");
      Console.WriteLine($"Named: {tuple2.id}, {tuple2.name}");
      
      // Alternative declaration
      var tuple3 = (age: 35, city: "New York");
      Console.WriteLine($"Alternative: {tuple3.age}, {tuple3.city}");
   }
}

The output of the above code is −

Unnamed: 25, Alice
Named: 30, Bob
Alternative: 35, New York

Tuples with Multiple Data Types

Tuples can hold more than two values and mix different data types −

using System;

class Program {
   static void Main(string[] args) {
      // Tuple with three different types
      (int id, string name, bool isActive) employee = (101, "John", true);
      
      Console.WriteLine($"Employee ID: {employee.id}");
      Console.WriteLine($"Employee Name: {employee.name}");
      Console.WriteLine($"Is Active: {employee.isActive}");
      
      // Tuple with four elements
      var product = (id: 1001, name: "Laptop", price: 999.99, inStock: true);
      Console.WriteLine($"Product: {product.name}, Price: ${product.price}");
   }
}

The output of the above code is −

Employee ID: 101
Employee Name: John
Is Active: True
Product: Laptop, Price: $999.99

Comparison: Classic Tuple vs Value Tuple

Conclusion

Tuples in C# provide an easy way to group multiple values without creating custom classes. While classic tuples use Tuple<T1, T2> syntax, value tuples offer better performance and readability with named elements. Use value tuples for modern C# development as they are more efficient and developer-friendly.