Version: May 21, 2025

Coding Standards for Class Member Ordering in C#

Organizing class members in a consistent and predictable order improves code readability, maintainability, and reduces merge conflicts. According to StyleCop's official rules, here's the recommended ordering for elements inside a class, struct, or interface.

Top-Level Member Ordering (SA1201 & SA1203)

Within a class, struct, or interface, use this order:

  1. Constant Fields
  2. Fields
  3. Constructors
  4. Finalizers (Destructors)
  5. Delegates
  6. Events
  7. Enums
  8. Interfaces (interface implementations)
  9. Properties
  10. Indexers
  11. Methods
  12. Structs
  13. Classes

This helps separate state, behavior, and nested types clearly.

Access Modifier Ordering (SA1202)

Within each group above (e.g., methods or properties), order by access:

  1. public
  2. internal
  3. protected internal
  4. protected
  5. private

Static vs Instance (SA1204)

Inside each access level, place static members first:

Readonly vs Non-Readonly Fields (SA1214 & SA1215)

When declaring fields, order them as:

  1. readonly
  2. Non-readonly

This rule helps you distinguish between immutable and mutable state.

Unrolled Method Example

Here’s how the methods section would look when fully expanded:

  1. public static methods
  2. public methods
  3. internal static methods
  4. internal methods
  5. protected internal static methods
  6. protected internal methods
  7. protected static methods
  8. protected methods
  9. private static methods
  10. private methods

Handling Exceptions to the Rule

Sometimes you’ll want to group related members (like interface implementations) together, even if it breaks the standard order.

Best practice: use partial classes to separate those concerns cleanly.

// File: MyClass.cs
public partial class MyClass {
    // Primary structure and logic
}

// File: MyClass.Interfaces.cs
public partial class MyClass : IMyInterface {
    // Grouped interface methods
}