10 things a Senior C# Developer should know

Can developers call themselves seasoned, experienced, or Senior if they don’t delve deep into C# as a programming language they work with? If a C# developer has just scratched the surface of working with C#, that is fine on a novice level, but a Senior level requires going the extra mile over many years. Before you hire a C# developer, first, you need to know precisely what are the things that make those developers experienced and in demand for the C# developer position you want to fill.

Sefa Teyek, Tech Lead and Backend Software Engineer at Proxify gave us an insight into the ins and outs of C# in this article.

The 10 things that a Senior C# developer should know and show

It is not only about having technical and soft skills, but a Senior C# developer must also havea solid resumé and present themselves as best as possible. After all, in the long run, they will exhibit communication skills with others in the company and show if they’re a good team player, but you want tobe able to see how well they communicate early on.

The resumé makes the first impression

Before the technical tests, the primary focus is first on the resumé. A well-prepared C# developer will have their resumé ready and polished, with clear summarization, an intro, and relevant context.

After reading the resumé, establishing whether the person is a solid C# developer with the required skills should be clear. But the resumé is not all there is, and we have to jump directly to the 10 essentials below.

The 10 must-know essentials

Now it’s time to go directly to the summed-up crucial things every experienced C# developer must know. Sefa shared a valuable checklist of everything every Senior C# developer must tick off.

1.Advanced C# features

A senior C# developer must explore advanced language features such as delegates, events, generics, lambda expressions, extension methods, and attributes. They should understand their usage and apply them appropriately in the code.

2.Design patterns

In this case, they should master a variety of design patterns like Singleton, Factory, Observer, Strategy, and others. Understand when and how to apply these patterns to write maintainable, flexible, and reusable code.

3.SOLID principles

A senior C# developer has to understand the SOLID principles (single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion) and apply them in the design and architecture to create modular and loosely coupled systems.

4.Dependency Injection (DI)

Learn and implement dependency injection techniques using frameworks like Microsoft’s built-in Dependency Injection framework of third-party containers like Autofac or Unity. They should also understand the benefits of DI and how it improves testability and maintainability.

using Microsoft.Extensions.DependencyInjection;
using System;

// Service interface
public interface IEmailService
{
    void SendEmail(string recipient, string message);
}

// Service implementation
public class EmailService : IEmailService
{
    public void SendEmail(string recipient, string message)
    {
        Console.WriteLine($"Sending email to {recipient}: {message}");
    }
}

// Consumer class that depends on IEmailService
public class NotificationService
{
    private readonly IEmailService _emailService;

    public NotificationService(IEmailService emailService)
    {
        _emailService = emailService;
    }

    public void SendNotification(string recipient, string message)
    {
        _emailService.SendEmail(recipient, message);
    }
}

// Composition root
class Program
{
    static void Main()
    {
        // Create a service collection
        var services = new ServiceCollection();

        // Register the dependencies
        services.AddScoped<IEmailService, EmailService>();
        services.AddScoped<NotificationService>();

        // Build the service provider
        var serviceProvider = services.BuildServiceProvider();

        // Resolve the consumer class
        var notificationService = serviceProvider.GetRequiredService<NotificationService>();

        // Use the consumer class
        notificationService.SendNotification("[email protected]", "Hello, John!");

        // Dispose the service provider if necessary
        if (serviceProvider is IDisposable disposable)
        {
            disposable.Dispose();
        }
    }
}

5.Asynchronous programming patterns

Dive deeper into asynchronous programming by mastering advanced techniques like parallel programming, Task Parallel Library (TPL), async streams, and custom async/await patterns.

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        // Asynchronous method invocation
        await DoAsyncWork();

        Console.WriteLine("Async work completed.");
    }

    static async Task DoAsyncWork()
    {
        Console.WriteLine("Starting async work...");

        // Delay asynchronously
        await Task.Delay(2000);

        // Perform an asynchronous HTTP request
        using (var httpClient = new HttpClient())
        {
            var response = await httpClient.GetAsync("https://jsonplaceholder.typicode.com/posts/1");
            var content = await response.Content.ReadAsStringAsync();

            Console.WriteLine($"HTTP response: {content}");
        }
    }
}

6.Multithreading and concurrency

A good senior C# developer should gain expertise in managing concurrent execution using threads, tasks, locks, synchronization primitives, and parallel programming patterns. They should understand the challenges and techniques of writing thread-safe code.

using System;
using System.Threading;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        // Multithreading with Task
        Task.Run(() => DoWork("Task 1"));
        Task.Run(() => DoWork("Task 2"));

        // Concurrency with Parallel.ForEach
        var numbers = new[] { 1, 2, 3, 4, 5 };
        Parallel.ForEach(numbers, number =>
        {
            Console.WriteLine($"Processing number: {number}, Thread ID: {Thread.CurrentThread.ManagedThreadId}");
            // Perform some work here
        });

        Console.WriteLine("Main thread finished.");
    }

    static void DoWork(string taskName)
    {
        Console.WriteLine($"Starting {taskName}, Thread ID: {Thread.CurrentThread.ManagedThreadId}");
        // Perform some work here
        Thread.Sleep(2000);
        Console.WriteLine($"{taskName} completed.");
    }
}

7.Secure coding practices

Here, they should know about secure coding practices and understand how to mitigate common security vulnerabilities, such as SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF). And they should follow the industry's best practices, especially for authentication, authorization, and data protection.

Examples of secure coding practices:

• Input validation

Always validating and sanitizing user input to prevent attacks like SQL injection and cross-site scripting (XSS).

// Example of input validation using regular expressions
string input = GetUserInput();
if (!Regex.IsMatch(input, "^[a-zA-Z0-9]+$"))
{
    // Invalid input, handle the error
}

• Parameterized Queries

Use parameterized queries or stored procedures to prevent SQL injection attacks when interacting with databases.

// Example of using parameterized query with SqlCommand
string username = GetUsername();
string password = GetPassword();
string query = "SELECT * FROM Users WHERE Username = @username AND Password = @password";

using (var command = new SqlCommand(query, connection))
{
    command.Parameters.AddWithValue("@username", username);
    command.Parameters.AddWithValue("@password", password);

    // Execute the query
}

• Password hashing

Store passwords securely using robust hashing algorithms like bcrypt or PBKDF2 with a ‘random salt.’

// Example of password hashing using BCrypt.Net library
string password = GetUserPassword();
string hashedPassword = BCrypt.Net.BCrypt.HashPassword(password);

• Authentication and authorization

Implement proper authentication and authorization mechanisms to control access to sensitive resources and actions.

// Example of checking user authorization before performing an action
if (UserIsAuthorized(userId, action))
{
    // Perform the action
}
else
{
    // Access denied, handle the error
}

• Secure communication

Use secure communication protocols like HTTPS (TLS/SSL) to encrypt sensitive data transmitted over the network.

// Example of using HttpClient with HTTPS
using (var httpClient = new HttpClient())
{
    // Make secure HTTPS requests
}

• Avoid hardcoding sensitive information.

Do not hardcode sensitive information like passwords or API keys directly in the code. Store them securely in configuration files or using secure storage mechanisms.

// Example of reading sensitive information from a configuration file
string apiKey = ConfigurationManager.AppSettings["ApiKey"];

8.Advanced database concepts

A senior C# developer should prove their proficiency in advanced database concepts like database design, indexing, query optimization, and stored procedures. Understand Object-Relational Mapping (ORM) frameworks like Entity Framework in-depth.

using Microsoft.EntityFrameworkCore;
using System;
using System.Linq;

// Entity class
public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }
}

// DbContext class
public class MyDbContext : DbContext
{
    public DbSet<Product> Products { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("YourConnectionString");
    }
}

class Program
{
    static void Main()
    {
        // Create the DbContext
        using (var dbContext = new MyDbContext())
        {
            // Create a new product
            var newProduct = new Product { Name = "New Product", Price = 9.99m };

            // Add the product to the DbContext
            dbContext.Products.Add(newProduct);
            dbContext.SaveChanges();

            // Retrieve all products from the DbContext
            var products = dbContext.Products.ToList();

            // Display the retrieved products
            foreach (var product in products)
            {
                Console.WriteLine($"Product: Id={product.Id}, Name={product.Name}, Price={product.Price}");
            }

            // Update the price of the first product
            var firstProduct = products.FirstOrDefault();
            if (firstProduct != null)
            {
                firstProduct.Price = 19.99m;
                dbContext.SaveChanges();
            }

            // Delete the last product
            var lastProduct = products.LastOrDefault();
            if (lastProduct != null)
            {
                dbContext.Products.Remove(lastProduct);
                dbContext.SaveChanges();
            }
        }
    }
}

9.Software architecture

They must showcase a good understanding of architectural patterns like MVC, MVVM, and Hexagonal Architecture. And they should learn about domain-driven design (DDD) principles and apply them to design scalable, maintainable, modular systems.

// Domain Layer

// Entity representing a Customer
public class Customer
{
    public int Id { get; private set; }
    public string Name { get; private set; }

    private Customer() { }

    public Customer(int id, string name)
    {
        Id = id;
        Name = name;
    }

    public void UpdateName(string newName)
    {
        Name = newName;
    }
}

// Repository interface for managing Customer entities
public interface ICustomerRepository
{
    Customer GetById(int id);
    void Add(Customer customer);
    void Update(Customer customer);
    void Delete(Customer customer);
}

// Infrastructure Layer

// In-memory implementation of the Customer repository
public class InMemoryCustomerRepository : ICustomerRepository
{
    private readonly Dictionary<int, Customer> _customers = new Dictionary<int, Customer>();

    public Customer GetById(int id)
    {
        _customers.TryGetValue(id, out var customer);
        return customer;
    }

    public void Add(Customer customer)
    {
        _customers.Add(customer.Id, customer);
    }

    public void Update(Customer customer)
    {
        _customers[customer.Id] = customer;
    }

    public void Delete(Customer customer)
    {
        _customers.Remove(customer.Id);
    }
}

// Presentation Layer

class Program
{
    static void Main()
    {
        // Initialize the customer repository
        ICustomerRepository customerRepository = new InMemoryCustomerRepository();

        // Create a new customer
        var customer = new Customer(1, "John Doe");
        customerRepository.Add(customer);

        // Update the customer's name
        customer.UpdateName("Jane Smith");
        customerRepository.Update(customer);

        // Retrieve the customer
        var retrievedCustomer = customerRepository.GetById(1);
        Console.WriteLine($"Retrieved Customer: Id={retrievedCustomer.Id}, Name={retrievedCustomer.Name}");

        // Delete the customer
        customerRepository.Delete(customer);
        var deletedCustomer = customerRepository.GetById(1);
        Console.WriteLine($"Deleted Customer: {deletedCustomer == null}");
    }
}

10.Distributed systems

It’s good here for the senior C# developer to gain even more knowledge on building distributed systems using technologies like message queues (e.g., RabbitMQ), distributed caches (e.g., Redis), and service-oriented architectures (SOA) or microservices architectures.

using StackExchange.Redis;
using System;

class Program
{
    static void Main()
    {
        // Connect to Redis
        var redis = ConnectionMultiplexer.Connect("localhost");

        // Get a reference to the Redis database
        var db = redis.GetDatabase();

        // Set a value in Redis
        db.StringSet("myKey", "Hello, Redis!");

        // Retrieve the value from Redis
        var value = db.StringGet("myKey");
        Console.WriteLine(value);

        // Perform operations on a hash
        var hashKey = "myHash";
        db.HashSet(hashKey, new[] { new HashEntry("field1", "value1"), new HashEntry("field2", "value2") });

        // Get all fields and values from the hash
        var hashEntries = db.HashGetAll(hashKey);
        foreach (var entry in hashEntries)
        {
            Console.WriteLine($"{entry.Name}: {entry.Value}");
        }

        // Remove the key from Redis
        db.KeyDelete("myKey");

        // Close the Redis connection
        redis.Close();
    }
}

All of the above is nailing down what a Senior C# developer needs to showcase as part of their knowledge and expertise. And just as there are essentials to know as a C# developer, there are also essential C# coding tasks to consider for evaluating how good their C# knowledge is.

Some preferable things to have and know

We’ve covered a strong portfolio and the essentials, the 10 must-know things for a Senior C# developer. Still, it doesn’t hurt for a developer to go the extra mile and show that they know more than what’s shown concisely in their portfolio.

For example, some ‘preferable’ things are not obligatory for the role but are nice to see. Sefa continues to list the nice-to-haves that are relevant in working with C#:

Frontend development

Familiarity with HTML, CSS, and JavaScript because this contributes to fullstack development and better collaboration with frontend developers.

UI/UX design

Basic understanding of UI (user interface) and UX (user experience) because it contributes to developing user-friendly and visually gorgeous apps.

Cloud computing

Knowledge of cloud computing platforms such as Microsoft Azure or Amazon Web Services (AWS) allows developers to implement scalable solutions and work with cloud-based infrastructures.

Mobile development

Familiarity with mobile app development through using frameworks such as Xamarin or React Native because this enables them to build cross-platform mobile applications along their C# experience.

DevOps practices

Understanding DevOps principles and practices can be valuable. It involves knowledge of continuous integration, automated deployment, containerization (e.g., Docker), and configuration management tools (e.g., Kubernetes). This knowledge contributes to streamlining the development and deployment processes.

Performance optimization

Expertise in performance optimization techniques and tools can help a Senior C# developer improve application speed, efficiency, and scalability. It involves knowledge of profiling tools, caching strategies, query optimization, and other performance-related considerations.

Security awareness

Understanding security principles and best practices in software development is crucial. Knowledge of common security vulnerabilities, secure coding practices, and authentication/authorization mechanisms enhances developers' ability to build secure applications.

Big data and analytics

Familiarity with data processing and analytics frameworks such as Apache Spark or Hadoop can be advantageous. It allows developers to work with large datasets, implement data-driven applications, and integrate data analytics capabilities into their solutions.

Cross-platform development

Knowledge of frameworks like .NET Core or Xamarin.Forms can enable a Senior C# developer to build applications on multiple platforms, including Windows, macOS, Linux, and mobile devices. This expands the reach and potential user base of the applications.

Knowledge of other programming languages

While C# is the primary language for a Senior C# developer, familiarity with other programming languages, such as JavaScript, Python, or Java, can facilitate collaboration and enhance problem-solving abilities across diverse projects or developer teams.

The benefits and demand

C# developers are and will continue to be in demand because this programming language is essential for most businesses. With C#, developers effectively make robust and secure applications that successfully run on the .NET platform. And they also create a broad range of Windows applications, web applications development, and games, among other things.

Let’s discuss saving time and money now. When developers use C#, this results in a shorter development time and saving on resources in the long run. This language is also highly scalable and easy to work with and maintain, simplifying the developer’s work. But also, it is consistent, offers smooth maintenance, and is backed up by a large community. These factors make C# incredibly popular among startups and larger tech giants because C# and .NET are used for enterprise-level apps predominantly.

This versatile programming language is here to stay for time to come, and its popularity will likely continue in upcoming years too. In fact, by 2035, it could boost popularity like never before and replace other popular languages on their “thrones” and top positions. This little factoid is important because it predicts the future of C# and, with that, its demand and hiring climate – information like this proves useful to the developers as much as the employers.

We needed a direct and relevant point of view about the popularity of C#, and Sefa, gladly explained the overall importance of C#:

“C# developers are in high demand in the software industry. The demand for C# developers can depend on location, industry, and specific job market conditions. They are sought after by companies that utilize Microsoft technologies and build applications using the .NET framework.”

And it’s not just as simple as it sounds because the usage of C# stretches beyond just Microsoft technologies. He goes on to list how the demand for C# developers is attributed to the following essential reasons:

• Web and Mobile Development: C# is commonly used for web development using frameworks like ASP.NET and ASP.NET Core. Additionally, C# is used for cross-platform mobile app development with frameworks like Xamarin. The popularity of web and mobile applications ensures a steady demand for C# developers.

• Enterprise Applications: C# is well-suited for developing large-scale enterprise applications. Many organizations, particularly finance, healthcare, and eCommerce, rely on C# to build robust and scalable software solutions. This demand for enterprise application development further contributes to the need for C# developers.

• Existing Codebase: Numerous companies have existing applications written in C# and rely on C# developers to maintain and enhance those systems. This ongoing need for C# expertise ensures a continuous demand for skilled developers. C# is the primary language for developing applications on the Microsoft platform. As a result, there is a consistent demand for C# developers from companies that use Microsoft technologies such as ASP.NET, Xamarin, and the .NET framework.

As he described, there is no clear cut when determining how big the demand is, but the demand definitely exists. As long as a C# developer is well-equipped with knowledge and expertise, they will likely meet the requirements of good job opportunities.

“The exact level of demand for C# developers can vary depending on various factors, including the location and specific job market conditions. However, C# developers are generally considered in high demand, and possessing proficiency in C# can open up several job opportunities in the software development field.”

How does this relate to CEOs and businesses?

We have to make a connection between the demand and the programming skills of the C# developers concerning businesses and jobs.

What happens when a business doesn’t hire a C# developer who is well-equipped with the essential skills? Let’s see.

“In that case, a business might suffer from limited or inefficient software development and inability to utilize Microsoft technologies. It will also affect integrating with existing systems and make this too difficult. Not having a seasoned C# developer will increase the dependency on external resources and ‘testing out’ unsuitable candidates. And, of course, a business will miss many good opportunities to stay relevant, and develop new software, without a good C# developer.”

On the other hand, there are some crucial benefits to a business once they hire an excellent senior C# developer, Sefa says, and it also pays off in the long run.

“Having a good C# developer means a business will always have access to a large community and resources and will always be versatile with app development products and stay relevant. Also, mastering the Microsoft technologies is something to take pride in, just like the scalability and enterprise-grade development that comes with using C#.”

But, for a Senior C# developer to be in steady demand, they should have a strong portfolio and know 10 essential things, as Sefa elaborated – these two aspects make their expertise valued and complete.

Final comments

Remember, a good C# developer is a solid, complex combination of more aspects – such as a solid portfolio, experience, understanding the 10 essential things, and having great soft skills. Save this listicle below that describes a top-tier Senior C# developer:

• Strong C# proficiency, especially with syntax, features, best practices, OOP (object-oriented programming), and design patterns.

• Experience with the Software Development Lifecycle and a solid understanding of Agile, Scrum, SDLC (software development lifecycle), code reviews, version control, and debugging.

• Analytical and problem-solving skills with analyzing complex requirements, devising practical solutions, and troubleshooting code effectively.

• Architecture and design patterns, being well-versed with software architecture principles, designing scalable, maintainable, and modular software solutions, and being familiar with MVC (model-view-controller) and MVVM (Model-View View-Model) patterns.

• Database and data access through proficiency with SQL, Microsoft SQL server, Entity framework, and other ORM (object-relational-mapping) frameworks.