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C# Interview Questions and Answers

This page provides a comprehensive collection of C# Interview Questions and Answers to help students, fresh graduates, and experienced .NET developers prepare for technical interviews. The questions range from basic C# programming concepts to advanced .NET application development topics frequently asked by top software companies.

C# is one of the most popular object-oriented programming languages developed by Microsoft and is widely used for building desktop applications, web applications, enterprise software, cloud services, APIs, mobile apps, and games using the .NET platform.

This interview guide includes beginner, intermediate, advanced, and scenario-based C# interview questions covering OOP concepts, collections, delegates, events, LINQ, asynchronous programming, multithreading, exception handling, memory management, ASP.NET Core, Entity Framework, and modern C# language features.

Difficulty
Beginner to Advanced
Topics Covered
OOP, LINQ, ASP.NET Core & More
Examples
Real C# Code Samples
Updated
July 2026

Why Learn C#?

C# remains one of the most in-demand programming languages for enterprise software development. Thousands of organizations use C# together with the .NET platform to build scalable business applications, cloud services, REST APIs, financial systems, e-commerce platforms, healthcare software, and cross-platform mobile applications.

Most .NET developer interviews evaluate your understanding of object-oriented programming, collections, delegates, events, asynchronous programming, LINQ, exception handling, multithreading, Entity Framework, and ASP.NET Core. Regular practice of interview questions significantly improves technical confidence.

Topics Covered

  • C# Fundamentals
  • Object-Oriented Programming
  • Classes & Objects
  • Inheritance & Polymorphism
  • Collections
  • Exception Handling
  • Delegates & Events
  • LINQ
  • Async & Await
  • Multithreading
  • ASP.NET Core
  • Entity Framework Core
Beginner
1. What is C#?
C# is an object-oriented programming language developed by Microsoft, used to build web, desktop, cloud, and enterprise applications using .NET.
Beginner
2. What are the main features of C#?
Strong typing, garbage collection, LINQ, async/await, OOP support, and platform independence via .NET.
Beginner
3. What are OOP principles?
Encapsulation, Inheritance, Polymorphism, Abstraction.
Beginner
4. Difference between value type and reference type?
Value types store data directly (int, struct). Reference types store memory references (class, array).
Beginner
5. What is .NET?
.NET is a developer platform providing runtime (CLR), libraries, and tools to build applications.
Intermediate
16. Difference between abstract class and interface?
Abstract class can have implementation. Interface defines contracts and supports multiple inheritance.
Intermediate
17. What is Garbage Collection?
Automatic memory management handled by CLR. Objects are cleaned using Generations 0, 1, and 2.
Intermediate
18. What is LINQ?
LINQ allows querying collections using SQL-like syntax:
var result = list.Where(x => x > 10).ToList();
Intermediate
19. What is async/await?
Used for asynchronous programming to avoid blocking threads.
Intermediate
20. What is dependency injection?
A design pattern where objects receive dependencies instead of creating them.
Advanced
31. Explain IDisposable and using statement
IDisposable is used to free unmanaged resources.
using (var reader = new StreamReader("file.txt")) { /* code */ }
Advanced
32. What is deadlock?
A situation where two threads wait forever for each other’s resources.
Advanced
33. What is Task vs Thread?
Thread is low-level OS concept. Task is higher-level abstraction managed by thread pool.
Coding Round
41. Reverse a string in C#
string s = "hello";
char[] c = s.ToCharArray();
Array.Reverse(c);
string result = new string(c);
Coding Round
42. Find duplicate elements in array
var duplicates = arr.GroupBy(x => x).Where(g => g.Count() > 1).Select(g => g.Key);
Coding Round
43. Fibonacci series
int a = 0, b = 1;
for(int i=0; i<n; i++) { Console.Write(a + " "); int temp = a; a = b; b = temp + b; }
Coding Round
44. Check palindrome string
string reverse = new string(s.Reverse().ToArray());
bool isPal = s == reverse;
Coding Round
47. Count word frequency
var freq = words.GroupBy(w => w).ToDictionary(g => g.Key, g => g.Count());
Coding Round
49. Remove duplicates from list
var unique = list.Distinct().ToList();

Continue Your Interview Preparation

Along with C#, software engineering interviews often include questions on ASP.NET Core, SQL Server, Entity Framework Core, LINQ, JavaScript, REST APIs, object-oriented programming, design patterns, and system design. Expanding your knowledge in these technologies will help you perform better in technical interviews and real-world software development projects.

Tips to Crack a C# Developer Interview

Employers hiring .NET developers expect candidates to possess both strong programming knowledge and practical development experience. Besides understanding the syntax of C#, you should be comfortable with object-oriented programming, exception handling, collections, multithreading, delegates, events, LINQ, asynchronous programming, dependency injection, and REST API development.

Prepare by solving coding problems, building ASP.NET Core projects, working with Entity Framework Core, creating Web APIs, and practicing SQL queries. Explaining your previous projects clearly is often as important as answering theoretical interview questions.

Recommended C# Learning Path

  • C# Language Fundamentals
  • Object-Oriented Programming
  • Collections & Generics
  • Delegates & Events
  • Exception Handling
  • LINQ
  • Async & Await
  • Multithreading
  • Entity Framework Core
  • ASP.NET Core MVC
  • Web API Development
  • Design Patterns & SOLID Principles

About This C# Interview Guide

This C# Interview Questions and Answers guide has been created as a comprehensive learning resource for students, freshers, software engineers, and experienced .NET developers. The questions are selected based on common interview patterns followed by startups, product companies, multinational organizations, and enterprise software companies.

The content is regularly updated to reflect modern C# language features, .NET releases, and current industry practices. Along with reading interview questions, candidates should build practical applications and solve coding exercises to strengthen their technical skills before attending interviews.