A 2020 HackerRank developer skills report revealed that approximately one of every five hiring managers plans to hire a C# developer. While a talented C# developer can help you develop and deploy code effectively, hiring the wrong person can cause major setbacks.
If you’re a developer seeking a role or a hiring manager filling up an open position, it’s always challenging to plan and prepare for the right C# technical interview questions when interviewing for a C# developer position.
This guide covers fundamental, intermediate, and advanced C# questions, practical scenarios, and behavioral inquiries that suit a C# developer role.
Fundamental C# Interview Questions
1. What is C#?
C# is an object-oriented programming language from Microsoft that developers can use to build applications running on .NET Framework. It’s also widely applied on open-source platforms as a general-purpose programming language to develop software components for a distributed environment.
2. Highlight the key features of C#.
C# is a popular programming language known for its simplicity, safety, consistency, and updatability as well as for being easy to learn. The language also has object-oriented programming concepts like inheritance, polymorphism, and encapsulation.
3. What are the key types of classes in C#?
A class, a fundamental part of an object-oriented programming language serves as a blueprint for creating an object. An object in this case is used in reference to a particular data structure that includes both data and code that operate on that data.
C# has four types of such classes:
- Abstract class: Abstract Class in C# helps create a member function without an implementation but must be implemented in the derived class.
- Static class: The static class in C# can be created using keyword static and only contains static members. Just like an abstract class, you cannot create an object for it.
- Partial class: here, the keyword ‘partial’ allows members to divide or share source (.cs) files partially.
- Sealed class: Sealed classes cannot be inherited by any other class, and that’s the purpose it’s created for.
Intermediate C# Interview Questions
4. How do you create a property in C#?
In c#, a property is a class member that provides a mechanism to read, write, or compute the value of a private field. There are two ways to create a property in C# using get and set accessors in the property definition.
The property you can create can have a get accessor, a set accessor, or both, depending on whether you want the property to be read-only, write-only, or read-write.
Here’s an example:
5. Explain what is meant by object pooling in C#.
Object pooling in C # is a software design pattern that allows objects to be reused or recycled instead of recreated. It reduces the amount of processing power that is required for the CPU to recreate an object and destroy calls.
6. What is the purpose of the ‘params’ keyword in C#?
C# params keyword defines a single parameter taking variable arguments. The params keyword should only be used when you want to pass a variable number of arguments of the same type into a method without expressly creating an array.
Here’s an example of using the params keyword:
using System;
public class Calculator
{
// Method that accepts a variable number of integers using the params keyword
public int Sum(params int[] numbers)
{
int sum = 0;
foreach (int num in numbers)
{
sum += num;
}
return sum;
}
}
class Program
{
static void Main()
{
Calculator calculator = new Calculator();
// Calling Sum method with different numbers of arguments
int result1 = calculator.Sum(1, 2, 3); // Passing 3 integers
int result2 = calculator.Sum(5, 10, 15, 20); // Passing 4 integers
int result3 = calculator.Sum(2, 4); // Passing 2 integers
// Outputting the results
Console.WriteLine($”Sum of 1, 2, and 3: {result1}”);
Console.WriteLine($”Sum of 5, 10, 15, and 20: {result2}”);
Console.WriteLine($”Sum of 2 and 4: {result3}”);
}
}
Advanced C# Interview Questions
7. What are the different ways in which a method can be overloaded in C#?
Method overloading is a key feature in Object-Oriented Programming (OOP) that lets you call methods with fewer argument lists. A method can be overloaded in C# through the following ways:
- Changing the number of parameters in a method
- Changing the order of parameters in a method
- Using different data types for parameters
For example:
public class Area {
public double area(double x) {
double area = x * x;
return area;
}
public double area(double a, double b) {
double area = a * b;
return area;
}
8. Explain the difference between task and async task in C#.
Async methods in C# allow asynchronous programming that lets tasks run concurrently. This enhances an app’s responsiveness. Async code primarily relies on Task<T> and Task—these two are constructs used to model work being done in the background. The async keyword designates a method as asynchronous, allowing it to conduct non-blocking operations and return a Task or Task<TResult> object.
Practical and Scenario-Based C# Questions
9. How Do You Implement A Custom Exception Handling Middleware In ASP.NET Core?
Middleware in ASP. NET Core is deployed to deal with Requests & Responses. It links these incoming HTTP requests and how an application responds to them. You can implement a custom middleware with ASP. NET Core Web Application will collect any exceptions that are generated while processing these requests.
Here’s how to implement a custom exception in Python using a Flask framework:
from flask import Flask, jsonify
import traceback
app = Flask(__name__)
# Custom exception handling middleware
@app.errorhandler(Exception)
def handle_exception(error):
# Log the exception (optional)
traceback.print_exc()
# Return a JSON response
response = jsonify({‘error’: str(error)})
response.status_code = 500
return response
# Route that raises an exception
@app.route(‘/divide-by-zero’)
def divide_by_zero():
# Example route that raises an exception
1 / 0
if __name__ == ‘__main__’:
app.run(debug=True)
Soft Skills and Behavioral Questions
10. Describe a Situation Where You Had to collaborate with a Team to Deliver a Successful .NET Project
I was fortunate to work on a .NET Core e-commerce project where we modernized an existing system while integrating some new features. During this project, I worked with a remote developer team.
We collaborated hand-in-hand through agile methodologies and daily stand-ups, splitting tasks per expertise/ level of skill set. We also stayed in constant communication via tools like Microsoft Teams and Azure DevOps, working together on tasks that we could collaborate on, such as optimizing database performance and securely implementing APIs.
Through collaboration, we managed to deliver a scalable platform without going over budget because of delays!
Checklist of Fundamental C# Interview Questions
To assist you in preparing for C# developer interviews, we’ve compiled a checklist of fundamental C# interview questions. This visual guide summarizes key topics every candidate should be ready to discuss, from the basics of object-oriented programming to essential coding practices. Use this checklist as a quick reference to ensure you’re well-prepared for your next interview, or as a tool to help structure your own interviews when hiring C# developers.
Explore the image below to review these crucial questions and their areas of focus.
There You Have it
Hiring a C# developer is a tedious process, and isolating the skills you need to make the right questions is the most challenging part but hopefully, we made it easier for you. Now you know what to look for and what interview questions to ask to spot the best candidate for your team.
And if you want to avoid this time-consuming process, feel free to reach out to us. We have more than a decade of experience in headhunting the best developers from all over the world.
