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C# junior developer interview questions | A wooden letter C against a white background, shot at an angle from the lower right corner of the letter.
June 16, 2023 · 7 min read

C# junior developer interview questions and answers

C# developers are in high demand. Unfortunately, with entrepreneurs, managers, and CTOs competing to build the best C# and .NET apps, finding the best talent is difficult. Moreover, making the wrong hire could cost your company thousands of dollars.

So if you want to hire the best C# junior developers, you must craft a compelling job description. Then, you need to test the skills and knowledge of the developers who apply to see whether they can meet your demands.

Interviews can help you learn more about each candidate’s coding background and test these skills. You’ll get to know your C# junior developers thoroughly, and you can dig into their applications.

But what questions should you ask?

Aside from the standard questions like “What have you accomplished?” and “What are your strengths?”, you’ll want to assess your candidate’s knowledge of the .NET framework. 

And in this blog, you’ll find example C# junior developer interview questions to do this.

C# interview questions for junior developers

Q: What is C#?


C# is a type-safe, object-oriented language that uses a component-oriented approach to develop .NET applications. The language is compiled by the .NET framework into Microsoft Intermediate Language, making it an object-oriented programming language of choice.

With C#, you can create various applications, including Windows apps, cloud-based API services, mobile apps for iOS and Android platforms, AI and Machine Learning (ML) software, blockchain applications, and serverless apps.

Q: What are some of C#’s key features?


  • Simplicity: C# does not have pointers or allow direct memory modification, distinguishing it from languages like C++ or C
  • Type safety: C# ensures that variable data types are accurately defined
  • Object-oriented: C# supports the creation and utilization of classes and objects
  • Component-oriented: C# lets developers reuse existing components without coding from scratch
  • Open-source: C# allows for app development on multiple operating systems, including Mac and Linux
  • Structured programming: C# enables breaking programs into functions, promoting better organization
  • Rich library: C# gives a range of built-in functions that expedite development
  • Speed: C# offers quick compilation and execution of code
  • Ease of use: Passing parameters is straightforward in C#

Q: What is meant by object-oriented programming?


Object-oriented programming (OOP), the approach used by C#, is designing software using objects that interact. This type of programming serves as an alternative to functional or procedural programming.

Q: How is C# different from C?


One significant difference between C# and its predecessor, C, is that C# is an object-oriented programming language, while C is a procedural programming language. Procedures simply execute a series of computational steps.

Some other differences include:

  • C is best suited for hardware apps and system programming, whereas C# is used for desktop and mobile apps, as well as web services
  • C draws on just 32 different keywords, whereas C# has 87
  • C places greater emphasis on functions, whereas C# is more oriented to design

Q: What is a class in C#?


Classes are user-defined blueprints used to create objects. They effectively combine different types of data into a cohesive unit. 

As an object-oriented language, C# employs classes to define a program’s structure, storage, and management of data.

Within a class, there are class members known as properties and methods. These members can be categorized as private, restricting their accessibility to only within the class, or public, enabling other parts of the program to access and use them.

Q: What is an object in C#?


An object refers to a real-world entity and is a single instance of a class. For example, let’s consider a class called “cats”. Within this class, we can have subclasses such as “Tabby”, “Maine Coon”, and “American Bobtail”, all considered objects.

Taking this further, let’s imagine a program that deals with books. First, we can create a Book class that includes properties like the title and author. Then, by instantiating multiple instances of the Book class, we can generate various Book objects, each with distinct titles and authors.

To create an object, we use the “New” keyword to construct an instance of the corresponding class, allowing us to access and use the class methods associated with that object.

Q: What is a method in C#?


In C#, a method is a code block that contains a series of statements used to perform operations. Developers must declare methods within a class or a structure, and they help save time by reusing code.

C# junior developer interview questions – more advanced

Q: What is Managed and Unmanaged Code?


In the .NET framework, code fits into two categories: managed and unmanaged.

Managed code is developed within the .NET framework and executed by the Common Language Runtime (CLR). Any language written in the .NET Framework is considered managed code. The CLR manages memory, security, and other execution-related tasks for managed code, providing built-in security features.

On the other hand, unmanaged code is developed outside the .NET framework and interacts directly with the low-level functions of the operating system. Examples of unmanaged code include legacy code from VB, ASP, and COM. 

Unmanaged code relies on the operating system for memory management, security, and other execution-related tasks. The developer’s responsibility is to ensure that unmanaged code is safe and secure.

Simply put, when the CLR executes code within the .NET platform, it’s considered managed code, while code executed by a runtime program outside of the .NET platform is classified as unmanaged code. 

Q: What is meant by garbage collection in C#?


In C#, memory management in an application is handled through a process known as garbage collection. This automatic process efficiently frees up memory no longer in use, allowing it to be reallocated for new purposes.

Q: What are the different types of classes in C#?


There are four types of classes in C#. These include:

Abstract classes: These provide a common definition for a base class from which other classes can be derived. The class consists of a methodology or a single approach.

Static classes: These contain static items that can only interact with other static items.

Partial classes: Allows methods, events, and properties to be split into separate/multiple .cs source files, which can then combine into one class at compile time. All methods from the source files can be accessed using the same object.

Sealed classes: Prevents users from inheriting from the class and restricts access to the class members, such as properties or methods.

Q: What’s the difference between fields and properties in C#?


In the context of classes and objects, a field is a member that serves as a storage location for holding a value. It can be associated with any data type. 

On the other hand, a property is a class member that facilitates the reading, writing, and computation of the value stored in a private field.

Q: What are the different types of control statements in C#?


There are three main types of control statements, each serving different purposes. These include:

  • Selection statements, which enable you to branch to different sections of code
  • Iteration statements, which enable you to loop through connections or perform the same series of operations repeatedly until a specified condition is met
  • Jump statements, which enable control of flow to shift to another section of code

Q: What are boxing and unboxing in C#?


In C#, developers use boxing and unboxing techniques to convert between .NET data types, allowing them to convert reference types to value types and vice versa. These processes are vital in establishing a unified view within C#.

Q: What’s the difference between String and StringBuilder in C#?


There are two types of objects for handling text data in C#: string objects and string builder objects.

String objects are immutable. This means they cannot be modified once created. Any attempt to modify a string object will result in the creation of a new string object in memory.

On the other hand, string builder objects are mutable, offering flexibility for developers to modify them as needed. Operations such as insertions, replacements, or appends can be performed on a string builder object. When modifications are made to a string builder object, the string is updated in-place, without the need for creating a new memory space.

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So these C# junior developer interview questions should help you hire an entry-level developer or two for your company.

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