C# Interview Questions

Life without questions is life without progress. Whether you are a new Computer Science graduate, a coding bootcamp graduate or a career switcher, the first question you should ask yourself is “How Prepared am I for a Job Interview?” Thanks to the internet, you don’t need to be blind-sided when it comes to the employment interview. There are plenty of helpful interview guides and tips that you can find on the web. It’s just a matter of choosing the right resources and applying what you’ve learned from them.

Tech jobs are arguably the best jobs of the future because they are high-paying and fast-growing. According to the U.S. Bureau of Labor Statistics (BLS), the number of IT jobs are expected to expand for the next few years. Software development is particularly the most sought-after job right now in the web industry. Many job analysts predict that this trend and line of job would continue to flourish in the future. So if you want to be a part of its growth and success, you should start your preparation now to make it happen.

C# INTERVIEW QUESTIONS

C# is a modern programming language that is on top of the list of the most in-demand programming languages of 2019 together with Java, Javascript, Python, PHP and MEAN.  C# is a versatile programming language that can be used in any platform; that’s why most employers and hiring managers are looking for skilled C# developers. It is important to note that employers and hiring managers are not looking for developers with an impressive resume but those who have the skills and expertise to deliver what is expected of them.

If you are preparing for a C# interview, below are examples of C# interview questions and their answers.

1. What is C#?

C# (pronounced “see sharp“) is an object-oriented programming (OOP) language created by Microsoft and standardized by  ISO and ECMA for use on the .NET platform. It was officially released in 2002. Since then, C# has seen numerous improvements with the most recent version being C# 6.0. While initially built to run on Windows, it was quickly ported to Linux and Mac OS X via the Mono project. Today, C# is open source and runs on the cross-platform .NET Core.

2. What are the important features of C#?

  • C# is a modern and simple, pure object-oriented programming language.
  • C# has the feature of versioning, meaning you can make a new version of module work with the existing version.
  • C# is type safe because it doesn’t allow unsafe casts like convert double to boolean and direct memory manipulation.
  • C# is many times faster than BASIC.
  • C# is scalable and updatable.
  • C# is used to develop Console application, Windows application, and Web application.

3. What is the difference between the “throw” and “throw ex” in .NET?

Throw” maintains and gives the complete original error stack information about the exception which occurred in the code. Whereas “throw ex” removes all hierarchy above the method containing the “throw ex” expression. It pretends that exception occurred on the line where “throw ex” was written.

4. Compare “string” and “StringBuilder” in C#

StringBuilder is mutable which means that once an object for StringBuilder is created, it can be modified later either using Append, Remove or Replace. While String is immutable, which means we cannot modify the string object and will always create a new object in the memory of string type.

5. Give some of the advantages of C# programming language?

C# is one of the most popular and influential programming languages worldwide. It has powerful frameworks and organized libraries that can rival with other languages.

Here are the Benefits of C# Programming Language.
1. It can be integrated or interoperate with other technologies, applications, languages or frameworks (e.g., .NET).
2. It’s a pure object-oriented language which allows the user to build easy-to-maintain modular based applications with reusable codes.
3. It has an automated item removal feature that collects, disposes and deletes all the garbage in the system to manage and unmanaged resources in C#.
4. It has a library that contains a rich collection of highly functional tools which makes implementation convenient.
5. It has a secure recovery system that blocks memory leaks.
6. It has a strong support unit back up by the Microsoft team to help users solve issues or respond to their queries.

6. What is the difference between a “struct” and a “class” in C#?

  • Class is a reference type that supports inheritance. Its variables are stored on Heap which is public by default.
  • Struct is a value type that does not support inheritance. Its variables are stored on Stack which is private by default.

7. What is the difference between “method overriding” and “method overloading?”

What is method overloading?
It’s the process of creating two or more methods/functions with the same name but different parameters in the same class. You can do this by changing or replacing the number of parameters and the data type of the arguments. This method is also known as Early Binding, Compile Time Polymorphism or Static Binding.

What is method overriding?
It’s the process of creating a method in the derived class with the same signature and name in the base class. This method is also called RunTime Polymorphism or Dynamic Polymorphism or Late Binding.

8. What is the difference between “dispose” and “finalize” methods in C#?

  • Dispose() -used to free or release unmanaged resources (e.g., files, database connections) when called explicitly.
  • Finalize() -used to free the unmanaged resources on the code before garbage collection happens.

9. Enumerate some exceptions in C#?

C# exception happens when an exceptional circumstance arises while a program is running (e.g., an attempt to divide by zero).

Here are some of the exceptions in C#.

  1. NullReferenceException – It reflects developer error when the user tries to access a member on a type whose value is null.
  2. ArgumentNullException – It happens when a null reference (Nothing in Visual Basic) is passed to a method that doesn’t consider it as a valid argument.
  3. DivideByZeroException – It occurs when there’s an attempt to divide an integral or Decimal value by zero.
  4. IndexOutOfRangeException – It’s thrown when there’s an attempt to access an element of an array or collection with an index that is outside its bounds.
  5. InvalidOperationException – It happens when a method call is invalid for the object’s current state.
  6. StackOverflowException – It occurs when the execution stack overflows because it contains too many nested method calls.

10. What are delegates and its types in C#?

Delegates are type-safe objects containing information about the function rather than data. They can define their own type parameters

Below are the types of delegates in C#.

  1. Single Delegate -used to invoke a single method.
  2. Multicast Delegate -used to invoke multiple methods on existing delegate instance using the + operator and – operator. However, the methods will be invoked in sequence as they are assigned.
  3. Generic Delegate -used to invoke a single method that doesn’t require to define the delegate instance. There are 3 types of generic delegates: Func, Action, and Predicate.

11. What is object pool in C#?

Object pool tracks the objects used in the code whenever there’s a request for a new object to reduce the object creation overhead.

12. List the differences between Static, Public, and Void

Static – It’s a keyword which declares the Main method as the global one and can be called without creating a new instance of the class.

Public –  It’s an access modifier keyword which tells the compiler that anyone can access the Main method.

Void – It’s a type modifier keyword which states that the Main method doesn’t return any value.

13. Name three ways to pass parameters to a method in C#

These are the three ways to pass parameters to a C# method: Value Parameters, Reference Parameters, and Out Parameters.

Value Parameters – It’s also known as “Passing Value-Type Parameters or Passing Parameters.” It happens when a variable is passed as value type which contains its data not the reference by default. Also, when the user made some changes in the value type parameter, it won’t reflect the originally stored data as an argument. Moreover, to modify the original data, you can use ‘ref’ or ‘out’ keyword to pass it.

Reference Parameters – This method accesses the argument’s memory location and passes it as a parameter instead of creating a new storage location. In this case, the change in the value can affect the argument.

Out Parameters – It’s used when a method returns multiple values. It can pass without its declaration and initialization. Also, it can use the var type in the method parameter list. However, it isn’t imperative that Out parameter’s name is the same in both function definition and call.

14. What is the difference between dynamic type variables and object type variables in C#?

Dynamic and Object Type Variables have the same function: type checking during the application life cycle. However, they check at different times. Dynamic Type Variables handle type checking at run time, and Object Type Variables handle type checking during compile time.

15. What are some of the features of generics in C#?

Generics enable developers to specify a class or a method that can work virtually with any data type. To do so, it delays the specification of the programming element’s data types until they are needed. Some of the features on Generics in C# are:

  • It makes codes type-safe, performance-optimized and reusable.
  • It helps you to get real-time information on the types used in a generic data type at runtime through reflection.
  • It allows you to create your own generic methods, classes, interfaces, delegates, and events.

WHAT’S NEXT?

You’ll come to know that all your preparations, reviews, and practices won’t be in vain because it will help you showcase yourself better in front of your future employers. Just remember to answer clearly and confidently to make your answers have a strong impact on your interviewers, and build their confidence in you.

Coding Dojo offers and teaches C# as one of its technologies to students or career-switchers who are up to a new journey. We support them throughout their learning and help them prepare for their applications, interview, and even until they land their first jobs. We, at Coding Dojo, wish you all the best and good luck to your interview!

For more information about Coding Dojo, please, visit www.codingdojo.com.

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2 thoughts on “C# Interview Questions

  1. Really cool post, highly informative and professionally written and I am glad to be a visitor of this perfect blog, thank you for this rare info!

  2. Really cool post, highly informative and professionally written and I am glad to be a visitor of this perfect blog, thank you for this rare info!

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