If you’re planning to hire a C# developer, it’s important to evaluate their knowledge and experience with the language. Here are 10 interview questions divided into easy, medium, and hard categories, that can help you assess the candidate’s proficiency with C#.

5 Easy C# Interview Questions

1. What is C#, and what are its unique features?
   C# is a modern, object-oriented programming language developed by Microsoft. It was designed to be simple, modern, and type-safe. Some of the unique features of C# include automatic memory management, lambda expressions, and LINQ (Language-Integrated Query).
2. What is a class in C#, and how is it used?
   In C#, a class is a blueprint for creating objects. It defines the properties and methods of an object, and allows developers to create instances of the class. Classes are used to organize code and to create reusable components in C#.
3. What is the difference between “==” and “equals” in C#?
   In C#, “==” is used to compare values, while “equals” is used to compare the content of two objects. The “==” operator compares the reference identity of the two objects, while “equals” compares the value of the objects.
4. What is a namespace in C#, and how is it used?
   A namespace in C# is a way to group related classes, structures, and interfaces. It allows developers to avoid naming collisions and to organize code into logical groups.
5. What is a delegate in C#, and how is it used?
   A delegate in C# is a type that represents a method signature. It allows developers to pass a method as an argument to another method or to store a method as a variable. Delegates are used for event handling and callback functions.

… 3 Medium Difficulty C# Interview Questions …

6. What is the difference between an abstract class and an interface in C#?
   In C#, an abstract class is a class that cannot be instantiated and can contain both abstract and non-abstract methods, while an interface is a contract that defines a set of methods that must be implemented by a class. Abstract classes can contain implementation code, while interfaces cannot.
7. What is a LINQ in C#, and how is it used?
   LINQ (Language-Integrated Query) in C# is a set of language extensions that allow developers to query data using a consistent syntax. It allows developers to query data from databases, XML files, and other data sources using a simple, easy-to-understand syntax.
8. What is a lambda expression in C#, and how is it used?
   A lambda expression in C# is an anonymous function that can be used to create delegates or expression trees. It provides a concise way to define a method in-line without having to define a separate method. Lambda expressions are commonly used in LINQ queries.

… And Finally, 2 Hard C# Interview Questions

9. What are extension methods in C#, and how are they used?
   Extension methods in C# allow developers to add methods to existing types without modifying the original source code. They are useful for creating methods that apply to a specific type, such as a string or a collection. Extension methods can make code more readable and reusable.
10. What is the purpose of the “yield” keyword in C#, and how is it used?
    The “yield” keyword in C# is used to create iterators. It allows developers to create a custom collection that can be iterated over using a foreach loop. The “yield” keyword allows developers to create a custom iterator without having to write all the plumbing code themselves, making it easy to create custom collections in C#.

Final Words

C# is a powerful and modern programming language that is widely used in software development. When hiring a C# developer, it’s important to evaluate their knowledge and experience with the language. The questions discussed in this article provide a good starting point for assessing a candidate’s proficiency with C#.

The easy questions about C#’s unique features, classes, namespaces, comparison operators, and delegates can help gauge the candidate’s understanding of the basics. These topics are fundamental for building object-oriented applications in C#.

The medium-level questions about abstract classes and interfaces, LINQ, and lambda expressions show the candidate’s knowledge of more advanced C# features. They also indicate the candidate’s experience in building and maintaining complex applications.

Finally, the hard-level questions about extension methods and the yield keyword highlight the candidate’s expertise in more advanced C# features. These questions demonstrate the candidate’s experience in working with C# and their ability to write efficient, scalable, and customizable code.