13 Sample C# Interview Questions and Answers

As a web developer proficient in C#, you know how to handle runtime errors and prevent programs from crashing. Knowing how to answer C# interview questions can keep you from making errors—or crashing—when it comes time to interview with a hiring manager.

With web developer jobs expected to grow by 23% over the next 10 years, C# programming and coding is in high demand. Knowing how to put your best foot forward during a C# interview can open up plenty of job opportunities.

While you can’t predict exactly which C# interview questions will come up, you can prepare ahead of time. Start by developing, practicing, and refining your answers to the sample questions in this article.

C# Interview Questions

1. Describe What C# Is and Why Developers Use It.
2. Compare C# to C and C++.
3. What Are the Different Data Types in C#?
4. Explain What Loops Are in C#.
5. What Is Garbage Collection in C#?
6. Describe the Difference Between Managed and Unmanaged Code.
7. What Is a Variable in C# and How Do You Create One?
8. What Are the Different Types of Classes in C#?
9. What Is the Model View Controller in C# and How Does It Work?
10. How Does Routing Work in MVC?
11. Describe the Purpose of Validation in MVC.
12. How Does the NET Framework Work With C#?
13. What Is Common Language Runtime in the .NET Framework?

Basic C# Interview Questions and Answers

Let’s start with the C# basics. These five C# interview questions will help you put your knowledge of data types, loops, and garbage collection into words.

Question #1: Describe What C# Is and Why Developers Use It.

Most web developer interviews will start with the basics, including an overview of your knowledge of C#. Make sure your answer has the following details:

• A definition of C#.
• What C# does.
• Why many web developers prefer C# over similar programming languages.

How You Could Answer

“C# (pronounced “C sharp”) is a strongly typed object-oriented programming language developed by Microsoft in 2000 as part of its .NET initiative. It’s designed to be simple and modern, with features such as garbage collection, type safety, and version support. It’s also based on the C programming language and shares similar syntaxes with other programming languages such as C++ and Java.

Developers use C# to create desktop and web applications and games because it’s:

• Compatible with Windows and Mac.
• Easy to write and maintain code in.
• Simple to learn.
• Integrated with the .NET Framework, which offers a range of libraries and app development tools.
• A high-performing code that doesn’t need to be interpreted.”

Question #2: Compare C# to C and C++.

C# and C++ are both derived from C. The three programming languages share similar syntaxes and symbols, but they work differently. Include the following details in your answer:

• Similarities between C#, C, and C++.
• Key differences between C#, C, and C++.
• The advantages and disadvantages of using C# over C and C++.

How You Could Answer

“C# and C++ are programming languages derived from C and share similar syntaxes and symbols. However, there are some notable differences between these programming languages.

For example, C# uses automatic garbage collection or memory management, while C and C++ do not. This allows C# users to automatically deallocate memory that is no longer in use, which reduces the need for complex code and manual memory management.

Unlike C and C++, C#:

• Comes with a rich class library that provides functionality for common tasks such as data and time, I/O operations, and networking.
• Is a strongly typed language, which requires programmers to define variables and methods with specific types to prevent runtime errors and provide better code organization.
• Is designed to be a more modern, high-level language that is easy to learn and use.

On the other hand, C and C++:

• Use pointers, which are references to memory locations (C# doesn’t allow direct use of pointers).
• Are platform independent, while C# code can only be compiled for the .NET platform.”

Question #3: What Are the Different Data Types in C#?

Demonstrate your knowledge of data types in C# by describing:

• What data types do.
• The most common data types.
• The purpose of each data type.

How You Could Answer

“In C#, data types specify the size and type of variable values. The most common data types that C# uses include:

• Numbers: These include integer types that store whole numbers and floating point types that store numbers containing decimals.
• Booleans: These are declared with the bool keyword and include true and false values.
• Characters: These store single characters surrounded by quotes such as “A” or “B.”
• Strings: These store sequences of characters and are surrounded by double quotes.”

Question #4: Explain What Loops Are in C#.

Developers use loops to save time, reduce errors, enhance code clarity, and provide coding flexibility. Here’s how you can answer C# interview questions about loops:

• Describe what loops are and how they work in C#.
• Discuss the three main types of loops and what they do.

How You Could Answer

“A loop in C# is a programming element that allows developers to repeat the execution of pieces of code until certain conditions are met. C# uses three types of loops, including:

• For loop, which allows developers to execute blocks of code at a set number of times. A loop counter variable keeps track of the number of times this loop gets executed.
• While loop, which allows developers to execute blocks of code repeatedly as long as certain conditions remain true.
• Do while loop, which is similar to a while loop but ensures that the block of code is executed at least once before its condition is tested.”

Question #5: What Is Garbage Collection in C#?

Developers use garbage collection to manage program memory in C#. Demonstrate your understanding of garbage collection by bearing these details in mind:

• What garbage collection is and what it does in C#.
• How garbage collection can prevent program crashes and bugs.

How You Could Answer

“Garbage collection in C# is a type of automatic memory management used to free up memory that is no longer in use. It runs continuously in the background and periodically scans a program’s memory. When it finds unused memory, it deallocates it so a program can use it again. The memory can also be discarded if a program doesn’t need it anymore.

When programmers forget to manually free up unused memory, a memory leak can occur. This can consume all the available RAM, resulting in bugs and crashes. Automatic garbage collection often eliminates these problems.”

C# Coding Interview Questions and Answers

The next three C# interview questions will cover coding, including the difference between managed and unmanaged code, variables, and classes.

Question #6: Describe the Difference Between Managed and Unmanaged Code.

Employers may ask C# interview questions that gauge your understanding of managed and unmanaged code. Include the following in your answer:

• A definition of both managed and unmanaged code.
• How managed and unmanaged code work.

How You Could Answer

“Managed code is executed and managed by a runtime environment such as the .NET Framework Common Language Runtime. The runtime of managed code takes care of memory management, security, and other important tasks, freeing up developers’ time and reducing the number of manual tasks they need to do.

Unmanaged code is code that an operating system executes directly. Developers have to manually manage memory and security for unmanaged code.”

Question #7: What Is a Variable in C# and How Do You Create One?

To successfully land a C# developer job, you’ll need to understand variables. Include these details in your answer to C# interview questions about variables:

• The purpose of variables.
• How to create variables.
• An example of how you create a variable with code.

How You Could Answer

“In C#, a variable is a named storage location in a computer’s memory that holds a value and is declared with a data type that determines the kind of data it can hold. The value of a variable can be changed during a program’s execution.

To create a variable in C#, I first specify the data type and name of the variable. I then assign a value to the variable at the time of declaration. Here’s what the code looks like:

In myVariable;

Int myVariable = 10;

String myString =

“My Variable”;
float myFloat = 4f;
double myDouble =
3.1;
bool myBoolean = true;”

Question #8: What Are the Different Types of Classes in C#?

Classes are critical to C# app development. They offer reusability, coding organization and structure, and efficient code testing. Show your knowledge of classes by including the following information in your answer:

• A description of classes.
• What classes contain.
• A list of C# classes and how they work.

How You Could Answer

“Classes are data structures in C#. They contain data members (such as fields), function members (such as methods, events, and properties), and nested types. C# typically uses nine different classes such as:

• Abstract classes, which can’t be instantiated and must be inherited by a child class.
• Sealed classes, which can’t be inherited by a child class.
• Static classes, which can’t be instantiated and only contain static members.
• Partial classes, which can be split over multiple files and combined at compile time.
• Dynamic classes, which are created at runtime and can have properties and methods added or removed dynamically.
• Generic classes, which can be parameterized with one or more types.
• Nested classes, which are declared inside other classes and used to encapsulate functionalities within parent classes.
• Anonymous classes, which are defined on the spot without explicit declaration and are normally used for specific purposes.
• Interface classes, which define sets of contract methods and properties and are implemented by other classes.”

C# MVC Interview Questions and Answers

The next couple of C# interview questions will focus on the Model View Controller (MVC) in C#. Be prepared to describe what MVC is and how it works in C#. This section will also cover routing and validations in MVC.

Question #9: What Is the Model View Controller in C# and How Does It Work?

Developers use MVC in C# to separate concerns in applications, leading to better maintainability, extensibility, and testability. When employers ask you to describe MVC, create your answer with these details in mind:

• The three components into which MVC separates applications.
• What each of the components represents in C#.

How You Could Answer

“Model View Controller (MVC) is a software architectural pattern used in C# programming to separate an application into three components: model, view, and controller.

In MVC architecture, the model represents the shape of an application’s data and is described by a class. The view represents the user interface or presentation layer of an application. The controller represents the component responsible for handling user input, processing it, and updating the model and view accordingly.”

Question #10: How Does Routing Work in MVC?

Explain what routing is and how it works in MVC by including the following in your answer:

• A brief description of routing.
• What routing does in MVC.

How You Could Answer

“MVC routing is the process of mapping a URL to a specific action in a controller. Once a request is made to an application, the routing engine examines the URL to determine the appropriate controller and action to handle the request.

A routing engine in MVC typically uses a set of predefined rules to determine how URLs should be mapped to controllers and actions. You typically find these rules in an application’s routing configuration, which is usually declared in the Global.asax file or in a separate configuration file. These rules can also include parameters that pass data to the controller action.”

Question #11: Describe the Purpose of Validation in MVC.

Provide an in-depth explanation of validation in MVC by including the following in your answer:

• How MVC validates user data.
• The types of validation included in MVC.
• Why validation is important.

How You Could Answer

“The purpose of validation in MVC is to ensure that the data submitted by a user is valid and meets certain criteria before it’s processed by an application. It validates data submitted by forms, model binding data, and query data. Additionally, validations can be applied at the model, view, and controller levels.

There are various types of validation in MVC, including:

• Server-side validation validates user inputs on the server side, such as user activity on an application.
• Client-side validation validates user inputs on the client side, usually with JavaScript. The data is then submitted to the server.
• Validation using third-party or external libraries.

By performing these validations, developers can avoid errors and maintain data integrity.”

.NET Interview Questions for C#

The last two C# interview questions will cover the .Net Framework and Common Language Runtime.

Question #12: How Does the .NET Framework Work With C#?

C# developers use the .NET Framework to build a variety of websites, desktop applications, and web services. Show your understanding of the .NET framework by describing:

• What the .NET framework is.
• How it works with C#.

How You Could Answer

“The .NET framework is a software development framework that provides a set of libraries and runtime environments for developing and executing applications on Windows-based systems. C# is designed specifically to work with the .NET framework.

When a C# application targets the .NET framework, the code is compiled in a portable executable file that can be executed on any machine that has the .NET framework installed. The .NET framework provides a runtime environment that loads the portable executable file and executes it.”

Additionally, the .NET framework provides Common Language Runtime. “

Question #13: What Is Common Language Runtime in the .NET framework?

Answer C# interview questions about Common Language Runtime (CLR) with the following:

• What CLR does in the .NET framework.
• Key benefits of CLR.

How You Could Answer

“The .NET framework provides Common Language Runtime (CLR), which manages the execution of application code and .NET libraries on different platforms such as Windows, Linux, and macOS. It provides memory management, security, exception handling, and thread management.

In C#, developers write code that targets the .NET framework and CLR takes care of executing that code on the target platform.

The key benefits of CLR include automatic memory management, simple code execution and security, language interoperability, simplified application deployment, and improved program performance.”

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