Class vs Struct vs Record: Definitions and Differences

When designing data structures in C#, understanding the differences between class, struct, and record is essential to making informed decisions. So in this article we will compare these data types and see the differences and use cases of classes, struct and record.

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Class

Reference Type: Classes are reference types, meaning they store a reference to the data rather than the data itself.

Heap Allocation: Objects are allocated on the heap, and garbage collection is responsible for memory management.

Use When: You generally use classes for complex data structures, long-lived objects, or when the size exceeds 16 bytes.

Example:

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

Use the keyword class to create a class in C#. You can specify an access modifier (private, public, protected, internal), if required, for the class.

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Struct

Value Type: Structs are value types, meaning they store the actual data directly.

Stack Allocation: Structs are typically allocated on the stack, which can lead to better performance for small, short-lived instances.

Use When: Opt for structs when the data structure is small, immutable, and logically represents a single value. Avoid structs if the data structure is large or mutable.

Example:

struct Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

Use the struct keyword to declare the struct (structure) in C#. You can use access modifiers, if required.

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Records

Reference or Value Type: Records can be either reference types (record class) or value types (record struct).

Value Equality: Unlike classes, records emphasize value equality, meaning two records with the same data are considered equal.

Immutability: Records are immutable by default, making them ideal for scenarios where the data should not change after creation.

Use When: Use records for immutable data structures, especially when you want concise syntax, like in request and response DTOs.

Example:

public record Person( string Name, int Age );

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When to Use Which

Use Class: For most scenarios, especially when dealing with complex objects or when the instance size exceeds 16 bytes.

Use Struct: For small, simple, and immutable data structures, particularly when performance is a concern.

Use Record: For immutable data with value equality, such as DTOs, or when you want the convenience of built-in methods for deconstruction and printing.

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Conclusion:

In conclusion, choosing between classes, structs, and records in C# depends on your specific use case. Classes are best for complex and long-lived objects, structs for small, simple, and performance-critical data, and records for immutable data structures with value equality. Understanding these distinctions allows you to optimize your code for performance, maintainability, and clarity.

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