C# Classes vs. Records vs. Structs: Understanding the Key Differences

C# provides three main ways to define data structures: Classes, Records, and Structs. Each has its unique use cases, and choosing the right one can improve performance, readability, and maintainability. Let's break down their differences!

?? 1. Classes – Reference Types

Classes are the most common type in C#. They are reference types, meaning they are stored on the heap and passed by reference.

Example: Class (Mutable by Default)

public class Person
{
    public string Name { get; set; }  // Mutable property
    public int Age { get; set; }

    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }
}        

Key Points:

? Supports inheritance

? Passed by reference (modifying one instance affects all references)

? Best for complex objects with behavior

? Mutable by default (unless explicitly restricted)

Usage:

var person1 = new Person("Alice", 25);
var person2 = person1; // Both reference the same object
person2.Age = 30;

Console.WriteLine(person1.Age); // Output: 30        

?? Both person1 and person2 point to the same object, so changes affect both.

?? 2. Records – Reference Types with Value-Like Behavior

Records were introduced in C# 9 to make working with immutable data easier. They are reference types like classes but compare by value instead of reference.

Example: Record (Immutable by Default)

public record Person(string Name, int Age);        

Key Points:

? Immutable (cannot modify properties after creation)

? Value-based equality (two records with the same data are considered equal)

? Supports inheritance (record classes)

? Cannot mutate properties unless using with-expressions

Usage:

var person1 = new Person("Alice", 25);
var person2 = person1 with { Age = 30 }; // Creates a new modified copy

Console.WriteLine(person1 == person2); // Output: False (different values)        

?? Unlike classes, modifying a record creates a new object rather than changing the original.

?? 3. Structs – Value Types

Structs are value types, meaning they are stored on the stack and passed by value (copying data instead of referencing). They are lightweight and ideal for small data structures.

Example: Struct (Efficient for Small Objects)

public struct Person
{
    public string Name { get; set; }
    public int Age { get; set; }
    
    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }
}        

Key Points:

? Passed by value (copy instead of reference)

? More memory-efficient for small objects

? Does not require garbage collection (stored on the stack)

? No inheritance (structs cannot derive from other structs or classes)

? Mutable by default (can be changed after creation)

Usage:

var person1 = new Person("Alice", 25);
var person2 = person1; // Copy of data, not a reference
person2.Age = 30;

Console.WriteLine(person1.Age); // Output: 25 (original is unchanged)        

?? Structs create a copy instead of referencing the original object. Changes don’t affect the original instance.

?? Key Differences: Quick Comparison Table

?? When to Use What?

? Use Classes when you need behavior and state (e.g., services, repositories, domain models).

? Use Records when working with immutable data and value-based equality (e.g., DTOs, configuration models).

? Use Structs for small, performance-critical objects (e.g., coordinates, colors, small utility data).

Final Thoughts ??

Understanding the differences between Classes, Records, and Structs is crucial for writing efficient and maintainable C# code. Each type has its strengths—choosing the right one depends on your use case.

Which one do you use the most? Drop your thoughts in the comments! ????

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