C# Clean Code

Introduction

Most readability issues in C# code come from two places:

1. weak naming
2. methods doing too many things

If you improve only these two areas, your code quality rises quickly.

1) Naming conventions that scale

Use intention-revealing names

A good name explains purpose without comments.

// BAD
int d; // elapsed days

// GOOD
int elapsedTimeInDays;

Follow C# casing conventions

• PascalCase: classes, methods, properties, constants
• camelCase: local variables, method parameters
• _camelCase: private fields

public class OrderService
{
    private readonly IOrderRepository _orderRepository;

    public async Task<Order?> GetOrderByIdAsync(int orderId, CancellationToken ct)
    {
        var order = await _orderRepository.GetByIdAsync(orderId, ct);
        return order;
    }
}

Prefer domain words over abbreviations

// BAD
var custMgr = new CM();

// GOOD
var customerManager = new CustomerManager();

Boolean names should read like questions

Good booleans: isActive, hasPermission, canExecute.

2) Method design principles

Keep methods small and single-purpose

If a method validates input, calculates data, writes to database, and sends email, it has multiple responsibilities.

public async Task ProcessOrderAsync(OrderRequest request, CancellationToken ct)
{
    Validate(request);
    decimal total = CalculateTotal(request.Items);
    var order = await SaveOrderAsync(request.CustomerId, total, ct);
    await NotifyCustomerAsync(order, ct);
}

Keep parameter count low

When a method needs many primitives, introduce a request object.

public record CreateUserRequest(
    string FirstName,
    string LastName,
    string Email,
    string Phone,
    Address Address);

public Task CreateUserAsync(CreateUserRequest request, CancellationToken ct);

Avoid boolean flag arguments

// BAD
RenderPage(page, true);

// GOOD
RenderPageForPrinting(page);
RenderPageForScreen(page);

Use guard clauses to reduce nesting

// BAD
public decimal GetDiscount(Customer customer)
{
    decimal discount = 0m;

    if (customer != null)
    {
        if (customer.IsActive)
        {
            if (customer.OrderCount > 10)
            {
                discount = 0.15m;
            }
            else
            {
                discount = 0.05m;
            }
        }
    }

    return discount;
}

// GOOD
public decimal GetDiscount(Customer customer)
{
    if (customer is null) return 0m;
    if (!customer.IsActive) return 0m;

    return customer.OrderCount > 10 ? 0.15m : 0.05m;
}

Avoid hidden side effects

Method names must match behavior.

// BAD
public bool CheckPassword(string password)
{
    if (Encrypt(password) == _storedHash)
    {
        Session.Initialize(); // hidden side effect
        return true;
    }
    return false;
}

// BETTER
public bool IsPasswordValid(string password) => Encrypt(password) == _storedHash;
public void InitializeSession() => Session.Initialize();

Common review questions

Before merging, ask:

• Can a new developer understand each name in 5 seconds?
• Does each method do one thing at one abstraction level?
• Are there flag arguments or too many parameters?
• Are there side effects not reflected by method names?

Summary

Clear naming and focused methods are the highest-ROI clean-code improvements in C#. Start there, then move to class design and architecture.