C# Interview Questions: Can you answer them all?

C_Sharp_wordmarkSo you want to land your dream job as a C# programmer? You will need to prove that you know your stuff before any organization will hire you. Here are ten of the most common interview questions that interviewers will use to test your technical knowledge and problem solving skills. Can you answer them all?

1. What are the advantages of C# over C, C++ or Java?

Like C++ and Java, C# is a high-level object-oriented programming language. It is generally more efficient than Java and has useful features such as operator overloading. C# is based on C++ but has several advantages over this older language: it is type-safe, more comprehensively object-oriented, and the syntax has been simplified in several important ways. Most importantly, C# interoperates exceptionally well with other languages on the .NET platform. For this reason, C# is a better choice for building applications for .NET.

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2. How are namespaces used in C#?

Classes in the .NET framework can be organized using namespaces. The scope of a class is declared using the namespace keyword. You can then include methods from the namespace in your code by including the line “using [namespace];” at the start of your program.

3. What is a constructor?

A constructor is the method of a class that is called when an object of that class is created. The constructor initializes class parameters and has the same name as the class.

4. What is a destructor?

A destructor deletes an object of the class from memory. It is called when the object is explicitly deleted by the code you write, or when the object passes out of scope, which can happen when the program exits a function. The destructor has the same name as the class, but with a tilde prefix.

5. How are methods overloaded in C#?

You can overload methods in C# by specifying different numbers or types of parameters in the method definition. Overloading can help to give your program the flexibility it needs to operate with different types of data input.

6. Why use encapsulation?

Encapsulation – combining function definitions and data together into a class – is used to separate parts of the code from the rest of the program. This allows the private data of an object to be hidden from the rest of the program, keep code clean and easy to understand, and allows classes to be reused in other programs.

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7. What is the difference between a class and a struct?

Whereas classes are passed by reference, structs are passed by value. Classes can be inherited, but structs cannot. Structs generally give better performance as they are stored on the stack rather than the heap.

8. What is the GAC?

The acronym GAC stands for Global Assembly Cache. The GAC is where assemblies are stored so that many different applications can share these assemblies. Multiple versions of assemblies can be stored in the GAC, with applications specifying which version to use in the config file.

9. How does .NET help to manage DLLs on a system?

When you have multiple DLLs on a system, you are in what is known as “DLL Hell”. Managing the DLLs can be particularly difficult if there are multiple versions of the various DLLs. In the .NET framework, assemblies are managed using the information stored in their metadata, and you can store multiple versions of each in the GAC.

10. What types of error can occur in a C# program?

The three possible types of C# error are as follows:

  • Syntax error. This type of error, which is identified during compilation, occurs because the programmer has used syntax incorrectly or included a typo in the code.

  • Logic error. This type of error causes the program to do something other than what the programmer intended. The program will output an unexpected result in response to tests.

  • Runtime error. This type of error causes the program to crash or terminate incorrectly.

If you can handle these questions, you stand a good chance of getting a job as a C# programmer. If you struggled with any of them, maybe you need to brush up on your C# programming skills? This online course on the fundamentals of C# programming could help.