Skill Check

100 C# Interview Questions

Learn how to answer C# questions well

122 lessons5.8 hoursEN & ES subtitles

About this course

You gain confidence through practice. But how do you practice technical interviews? By going through 20 of them.

This course will ask you real-world C# interview questions, including questions on technologies around C#. Get practice interviewing while also learning the answers to some of the questions you may have around C#.

Every lesson, in the open

122 lessons · 5.8 hours of video. Here's exactly what's inside.

Round 1Your first set of four interviews.
  1. 1
    Course Introduction 1 lesson · 4 min
    • Introduction 4:17
  2. 2
    Interview One 6 lessons · 14 min
    • The Questions 0:31
    • What is the difference between a value type and a reference type in C#? 3:07
    • What is middleware in the ASP.NET Core pipeline? 2:03
    • What is git and what are some of the benefits? 2:50
    • What is a design pattern? 3:51
    • How do you use git to start working on a repository? 1:37
  3. 3
    Interview Two 6 lessons · 17 min
    • The Questions 0:29
    • What is WinForms? 2:45
    • What is WPF, and how does it differ from WinForms? 4:09
    • Explain the difference between string and StringBuilder. 3:01
    • How do MVC and Razor Pages differ? 3:09
    • Explain the Factory pattern. 3:19
  4. 4
    Interview Three 6 lessons · 14 min
    • The Questions 0:31
    • What is XAML? 2:57
    • What is the purpose of namespaces in C#? 3:01
    • What does the var keyword do, and when can you use it? 2:36
    • How is dependency injection configured in ASP.NET Core? 2:09
    • What problem does the Observer pattern solve? 2:17
  5. 5
    Interview Four 6 lessons · 7 min
    • The Questions 0:34
    • Describe the steps in git from making a change to getting it into the repository. 1:24
    • What is the MVVM pattern? 1:46
    • How do you display a simple message box in WinForms? 0:47
    • How do you display a simple message box in WPF? 1:17
    • How does the using statement relate to resource management? 1:33
Round 2Your second set of four interviews.
  1. 6
    Interview Five 6 lessons · 10 min
    • The Questions 0:35
    • What file defines environment-specific settings (e.g., Development vs. Production)? 2:25
    • How does the Decorator pattern work? 1:31
    • Define a dependency property in WPF. 1:16
    • What is the difference between a Form and a Control in WinForms? 1:03
    • Describe the Singleton pattern and a scenario for its use. 3:37
  2. 7
    Interview Six 6 lessons · 14 min
    • The Questions 0:40
    • What are the default options for settings in an ASP.NET Core project? 4:28
    • Where would you store settings that were specific to your machine? 2:15
    • How do you access settings in .NET? 2:33
    • How do you add your own source for settings? 2:32
    • Explain changes needed to get app config and web config to work in .NET 1:38
  3. 8
    Interview Seven 6 lessons · 11 min
    • The Questions 0:37
    • What is an event handler, and how do you wire one up? 0:46
    • Compare the three dependency injection service lifetimes in .NET. 3:38
    • What are the various ASP.NET Core web project types? 1:47
    • Compare Abstract Factory vs. Factory Method. 1:52
    • Explain the difference between git merge and git rebase. 2:44
  4. 9
    Interview Eight 6 lessons · 18 min
    • The Questions 0:39
    • Explain microservices vs monoliths and which you prefer. 4:36
    • Explain Docking vs. Anchoring for layout in WinForms. 2:48
    • How do you implement CORS in an ASP.NET Core app? 3:01
    • Explain async/await and how it differs from using Task.Run. 4:04
    • Describe the Facade pattern. 2:51
Round 3Your third set of four interviews.
  1. 10
    Interview Nine 6 lessons · 22 min
    • The Questions 0:42
    • Compare an abstract class and an interface. When would you choose one over the other? 4:53
    • What are generics in C#, and why are they useful? 3:44
    • What is Dependency Injection, and how does it relate to patterns? 4:49
    • What is the purpose of the .gitignore file and how do you use it? 4:12
    • What techniques help virtualize large collections in a ListView or DataGrid in WPF? 3:24
  2. 11
    Interview Ten 6 lessons · 18 min
    • The Questions 0:34
    • How do you implement an MDI application in WinForms? 1:31
    • Explain the difference between struct and class. 3:18
    • What are some things to consider about nullability? 5:42
    • What is boxing and unboxing? 3:17
    • Describe the different types of properties and their options. 3:45
  3. 12
    Interview Eleven 6 lessons · 18 min
    • The Questions 0:32
    • Describe the difference between interfaces and inheritance. 7:16
    • How do you create and switch to a new branch in git? 0:35
    • Describe how you would implement logging in .NET. 5:16
    • When would a method benefit from being async? 1:25
    • Describe what health checks are and how they work. 2:58
  4. 13
    Interview Twelve 6 lessons · 17 min
    • The Questions 0:35
    • What is the difference between overloading and overriding a method? 3:15
    • What is the difference between const and readonly? 2:11
    • Explain the difference between shallow copy and deep copy. 3:20
    • What is the difference between the stack and the heap? 2:57
    • How does garbage collection work in C#? 4:52
Round 4Your fourth set of four interviews.
  1. 14
    Interview Thirteen 6 lessons · 19 min
    • The Questions 0:32
    • What is the purpose of the finalize and dispose methods? 4:38
    • Explain covariance and contravariance in generics. 3:14
    • What are anonymous types in C#? 2:47
    • What are Func<>, Action<>, and Predicate<> used for? 3:15
    • Explain the async and await keywords. 4:56
  2. 15
    Interview Fourteen 6 lessons · 15 min
    • The Questions 0:35
    • How does exception handling work with async/await? 2:07
    • What is reflection in C#? How is it used? 2:39
    • What is dynamic and what is it used for? 2:15
    • What is the difference between a record and a class? 4:51
    • What is the difference between authentication and authorization? 2:36
  3. 16
    Interview Fifteen 6 lessons · 14 min
    • The Questions 0:41
    • Describe the IDisposable pattern and how you implement it correctly. 1:47
    • What's the difference between a Razor page and a Razor Component? 2:15
    • When would you use an API vs GRPC? 1:55
    • Compare Entity Framework Code First to Database First. 2:42
    • Explain the difference between public, private, protected, internal, and protected internal. 4:43
  4. 17
    Interview Sixteen 6 lessons · 16 min
    • The Questions 0:35
    • What is polymorphism and encapsulation? 4:42
    • What is LINQ and when would you use it? 3:34
    • What is your error-handling strategy in C#? 4:45
    • Describe resolving a merge conflict in git step by step. 2:51
    • Describe the various rendering options in Blazor. 3:55
Round 5Your fifth set of four interviews.
  1. 18
    Tooling Interview 6 lessons · 18 min
    • The Questions 0:31
    • What is Docker and when would you use it? 5:33
    • What is Bootstrap and what are its benefits? 2:53
    • Explain what NuGet is and how it works. 3:37
    • Explain YAML and JSON. 2:38
    • What is Aspire and how does it help developers? 2:48
  2. 19
    Databases Interview 6 lessons · 38 min
    • The Questions 0:45
    • What are some differences between SQL and NoSQL databases? 10:17
    • What are primary keys, clustered indexes, and non-clustered indexes in Microsoft SQL Server? 10:01
    • Tell me about three database types you have used and what their strengths are. 2:48
    • What are some safety factors to consider when connecting C# to a database? 6:13
    • What are some things to consider when planning for database disasters? 8:22
  3. 20
    CI/CD Interview 6 lessons · 18 min
    • The Questions 0:40
    • What does CI/CD mean? 3:18
    • What are the differences between Azure DevOps and GitHub for CI/CD? 3:38
    • How do you check code quality in your CI/CD process? 3:20
    • What tools or strategies can you use to protect applications secrets? 4:14
    • How can a developer replicate the production environment locally? 2:45
  4. 21
    AI Interview 6 lessons · 23 min
    • The Questions 0:39
    • What is RAG and MCP? 4:52
    • Explain how an LLM comes to a conclusion. 2:22
    • What security implications are there around using AI in software development? 6:01
    • Tell me how you use AI in software development. 3:48
    • What are the benefits and drawbacks of integrating an LLM into a software product? 5:54
  5. 22
    Course Conclusion 1 lesson · 2 min
    • Conclusion 2:21
Tim Corey

Hi, I'm Tim Corey.

I learned software development the hard way, with lots of dead-ends, confusion, and knowledge gaps. I kept thinking, “It shouldn't be this hard!” Now I teach students how to think and code like professional developers. My goal is to make it easier for you to become a developer.

25+ Years experience
400,000+ Students taught
400+ Hours of training
10x Microsoft MVP

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