Records & Record Structs in C#

Create immutable data types with record classes and record structs (C# 10+) — with expressions, deconstruction, inheritance, and value equality.

Introduction to Records

1. What is a Record?

A record is an immutable reference type optimized for holding data.

Creating Records

1. Positional Record Syntax

Declare properties in parentheses — the compiler generates everything.

2. Nominal Record Syntax

Declare records with explicit property bodies — more control.

3. Record with Validation

Add a compact constructor to validate data at construction time.

4. Mutable Records

Records are immutable by default, but you can make individual properties mutable by using `{ get; set; }` instead of `{ get; init; }`. The record still provides value equality and `ToString()` — just without the immutability guarantee.

Value Equality

1. Records Use Value Equality

Unlike classes, records with the same data are `==` equal.

with Expressions

1. Non-Destructive Mutation with with

`record with { Prop = newValue }` returns a new record with only that property changed.

Deconstruction

1. Deconstructing a Record

Positional records auto-generate `Deconstruct()` — unpack with tuple syntax.

Record Inheritance

1. Extending a Record

Records support inheritance — a derived record adds more properties.

record struct (C# 10+)

1. record struct vs record class

`record struct` lives on the stack — ideal for small, short-lived data.

Records vs Classes vs Structs

1. When to Use Each

Records, classes, and structs each suit different scenarios.