Exploring Record Types in C# 9 and Beyond

C# 9 introduced record types, a powerful feature for creating immutable reference types with value-based equality. Let’s explore why and when to use them.

What are Records?

Records are reference types that provide built-in functionality for encapsulating data. They’re perfect for DTOs, value objects, and immutable data structures.

public record Person(string FirstName, string LastName, int Age);

This simple declaration gives you:

• Immutability by default
• Value-based equality
• Built-in ToString() override
• Deconstruction support

Value-Based Equality

Unlike classes, records compare by value:

var person1 = new Person("John", "Doe", 30);
var person2 = new Person("John", "Doe", 30);

Console.WriteLine(person1 == person2); // True!

Non-Destructive Mutation

Use the with expression to create modified copies:

var person = new Person("John", "Doe", 30);
var olderPerson = person with { Age = 31 };

Records vs Classes

Use records when:

• You need value-based equality
• Your type is primarily for holding data
• You want immutability

Use classes when:

• You need identity-based equality
• You have complex behavior
• Mutability is required

Record Structs (C# 10)

C# 10 added record structs for value type records:

public record struct Point(int X, int Y);

Records are a game-changer for writing clean, concise data models. Start using them in your next project!