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Janki Mehta
Janki Mehta

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How to Assess C# Skills and Experience in Interviews

As a hiring manager looking to fill C# developer roles, you want to make sure you properly assess candidates' skills and experience with the language and related technologies. Vetting C# capabilities thoroughly during the interview process is crucial for identifying the right people to add to your team.

In this blog post, we’ll explore tips and techniques for evaluating C# developers' abilities through questions, code samples, and practical exercises. Read on to learn how to dig into candidates' knowledge across a range of areas like .NET Framework, object-oriented principles, web development, and cloud platforms. With the right interview approach, you can gain invaluable insights into applicants' real-world expertise.

Review Their Resume and Background

The interview begins long before the actual meeting itself. Closely examining a candidate's resume, cover letter, and other background materials provides early clues about their experience with C# and related technologies.

Here are key things to look for:

  • Previous Job Titles and Descriptions: Look for specific roles like C# Developer, .NET Developer, and Web Applications Developer. Also, note how long they spent in each relevant position. Longer tenures suggest stronger abilities.
  • Projects and Achievements: Scan for examples of major projects or apps they built with C#. What problems did they solve, and what specific tasks did they handle? How large were the codebases?
  • Open-source Contributions: Involvement with open-source C#/NET projects, like contributing to .NET Core, indicates a passion for the ecosystem. Even minor bug fixes to GitHub repositories can demonstrate real coding abilities.
  • Overall Years of Experience: While not always a perfect proxy, more years working professionally with C# generally equates to deeper knowledge and exposure to more aspects of the language and framework.

Any other background information, like speaking at a .NET user group meeting or taking a Udemy course on ASP.NET Core, also helps paint a picture of their overall skills.

By cataloging candidate’s backgrounds ahead of time, you’ll have a framework to dig deeper into their experiences during the interviews.

Ask About Their Education and Training
Formal education and training provide a structured way for developers to build C# skills. Be sure to discuss these topics:

  • Related Major/Degree: Did they study computer science, software engineering, or another related field? Relevant university degrees suggest basic coding skills and theoretical knowledge.
  • C# or .NET Focused Courses: Many schools offer specific classes on building applications and web services with C#. These courses dive deep into language features and framework capabilities. Ask about any noteworthy projects or apps created for class assignments.
  • Certifications: C# and .NET certifications demonstrate commitment to mastering the technology. Microsoft, in particular, offers various credential programs related to its development stack, like the Microsoft Certified Solutions Developer certification. There are also 3rd party certification bodies with C#-focused programs.
  • Online Classes: With the wealth of e-learning content available today, many developers supplement their practical experience with online classes. Platforms like Pluralsight, Udemy, and LinkedIn Learning all offer robust C# content. See if they’ve taken relevant courses covering ASP.NET, Unity, or other topics.
  • Bootcamps/Intensive Training: Some candidates from non-traditional backgrounds attend intensive coding boot camps focused on C# and .NET skills. These accelerated 3-12 week programs aim to equip new developers with practical abilities through hands-on training. Ask about their boot camp curriculums and post-graduation projects.
  • Conference/Meetup Attendance: Active membership in the C# community, through attending conferences like Microsoft Ignite or Meetup groups, demonstrates engagement. Speaking/presenting at these events takes it a step further. The combination of formal coursework, certifications, online training, and community participation all help build a well-rounded skillset.

Discuss Their Hands-On C# Coding Skills

While resumes and education provide background context, you need to directly assess candidates’ hands-on C# skills during the interview. Through coding challenges, take-home projects, and questions on language internals, you can get a sense of how they apply their knowledge.
Here are effective ways to evaluate their proficiency:

  • Give Coding Challenges Focused on C#/NET Concepts: Have them write LINQ queries, build objects that implement interfaces, work with asynchronous code, or demonstrate other language-specific capabilities with short coding prompts. This shows if they can quickly translate concepts into real C# code.
  • Provide Realistic Coding Problems Resembling On-the-job Tasks: Avoid puzzles and theory-heavy algorithm questions. Instead give prompts like building part of a web API, a simple IoT application, or code to parse/process a sample data file. The goal is to simulate actual problems developers face day-to-day.
  • Ask About Debugging Techniques: Every developer spends significant time fixing bugs. See how they walk through diagnosing different issues like infinite loops, race conditions between threads, unhandled exceptions, etc. This demonstrates how they approach debugging in their daily work.
  • Discuss Design Principles Like SOLID: Well-designed C# code properly implements key object-oriented principles and design patterns. Dive into their knowledge of topics like the single-responsibility principle, inversion of control/dependency injection, and others.
  • Explore Language Internals: Developers working extensively with C# should have an advanced grasp of how the language itself functions under the hood - topics like memory management, garbage collection, extension methods, etc. Pose questions that demonstrate their understanding of internal processes. The aim is to give them opportunities to show competence across a spectrum of important C# coding concepts and practical techniques. If they struggle with basic language features or stumble on realistic problems, that should raise flags about gaps in their skills.

Explore Their .NET and Related Knowledge

C# does not exist in a vacuum. Experienced C# developers should have knowledge of the key frameworks, libraries and ecosystems that play important roles in building .NET applications.

  • ASP.NET: For web development, understanding ASP.NET and frameworks like ASP.NET Core is crucial. See if they have experience building web forms and MVC applications. Ask about Razor Pages, dependency injection, EF Core, authentication/authorization, and other common components of the stack.
  • Windows Desktop Development: Windows Forms and WPF are used for building traditional desktop GUI apps. While less common today, these are still relevant skills. Have they worked on WinForms or WPF apps in past roles? What UI development tools and patterns are they familiar with?
  • Unit Testing: Writing unit tests is a key part of professional C# development. Quiz them on their knowledge of frameworks like MSTest, NUnit, and xUnit. See if they follow Test Driven Development (TDD) principles in their work.
  • Asynchronous Programming: C# developers should understand async/await patterns for building responsive applications. Ask how they implement long-running processes without blocking execution threads. What experience do they have with Task objects?
  • Object-Relational Mapping: Most applications need to interface with databases, and ORM tools like Entity Framework Core facilitate this. Check if they have configured EF Core contexts and built repositories/services for data access.
  • REST APIs: Consuming and creating REST-based web APIs is near-universal. Do they have hands-on experience with API concepts like endpoints, verbs, authentication, and OpenAPI/Swagger documentation? Have they built web APIs from scratch?
  • Cloud Platforms: Services like Azure, AWS, and GCP are mainstream today. See if they have exposure deploying or managing .NET applications on these platforms, using services like App Services, Functions, and VMs. The wide .NET ecosystem greatly expands what developers can build with C#. Experience applying related technologies and libraries is a must for senior roles.

Learn About Past Projects and Accomplishments

Another perspective into candidates' capabilities comes from the actual projects they have built and led using C#.

  • Examples of Complete Apps or Complex Features: Have they designed and built an entire application from the ground up with C#? Maybe for a past employer or as a personal project? Understanding the scope and complexity provides insights into their ability to put concepts into practice.
  • Project Challenges: No major project is without roadblocks. What difficult problems did they encounter? How did they react to unexpected issues arising? What did they learn in the process?
  • Team Dynamics: Most developers work on teams. Did they play a lead role in defining architecture and making technical decisions? Or were they mainly focused on heads-down coding? Explore project leadership skills.
  • Components they Developed: On large codebases spread across teams, dig into the specific components, services, and features they own building. This demonstrates their exact coding responsibilities and skills.
  • Source Control Processes: Ask how they use Git and GitHub/Azure DevOps to collaborate on code projects. Do they use proper branching strategies and PR workflows?
  • Code Reviews: How are they involved with reviewing and providing feedback on other developers' code? This builds shared code health and quality standards across teams.
  • Documentation: In addition to writing code, do they help create technical spec documents, API references, inline comments, wiki pages, release notes, and other artifacts commonly worked on by developers? The better the grasp they have on the end-to-end development process, the stronger indication it is of their capabilities and experience

Final Words

Evaluating C# and .NET Development skills thoroughly during interviews takes thoughtful planning and preparation. But it’s time well spent to ensure you are making informed hiring decisions. By reviewing resumes, diving into education and training, conducting coding exercises, discussing .NET ecosystem knowledge, and exploring past projects, you can assemble a complete picture of a developer's abilities.
Keep in mind that very few candidates will check every box across the spectrum of potential topics. The goal is not to find some mythical "perfect" applicant. Instead, aim to use the interview process to filter for developers who meet the key skill bar for your specific team and projects. With rigorous C# interview practices in place, you'll avoid bad hiring mismatches and assemble a strong development team.

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