common C# and .NET interview questions with their answers ( AI generated)

Here are common C# and .NET interview questions with their answers to help you prepare:

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1. What is the difference between ref and out in C#?

• ref: Requires the variable to be initialized before being passed.
• out: Does not require the variable to be initialized before passing; it must be assigned a value inside the method.

Example:

void RefExample(ref int x) { x += 10; }
void OutExample(out int x) { x = 10; }

int a = 5;
RefExample(ref a);  // a = 15

int b;
OutExample(out b);  // b = 10

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2. What is the purpose of async and await in C#?

• async: Marks a method as asynchronous, allowing it to run without blocking the main thread.
• await: Pauses the execution of the method until the awaited task is complete.

Example:

async Task<string> GetDataAsync()
{
    await Task.Delay(1000); // Simulates delay
    return "Data Loaded";
}

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3. What is the difference between IEnumerable and IQueryable?

• IEnumerable:
  • Executes the query in memory.
  • Best for in-memory collection iteration.
• IQueryable:
  • Executes the query on the database (deferred execution).
  • Useful for querying large datasets.

Example:

IEnumerable<int> enumerable = myList.Where(x => x > 10);
IQueryable<int> queryable = myDbContext.Entities.Where(x => x > 10);

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4. Explain Garbage Collection in .NET.

• Garbage Collection: Automates memory management by reclaiming unused memory objects to free up resources.
• Generations:
  • Gen 0: Short-lived objects (e.g., temporary variables).
  • Gen 1: Medium-lived objects.
  • Gen 2: Long-lived objects (e.g., static fields).

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5. What is the difference between struct and class?

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6. Explain Dependency Injection (DI).

• Definition: A design pattern where objects are provided with their dependencies at runtime rather than hardcoding them.
• Benefits:
  • Improves code modularity.
  • Enhances testability.
• Example:

public interface IService { void Serve(); }
public class MyService : IService { public void Serve() => Console.WriteLine("Service Called"); }

public class Consumer
{
    private readonly IService _service;
    public Consumer(IService service) { _service = service; }
    public void Start() { _service.Serve(); }
}

// Usage (with DI Container, e.g., ASP.NET Core)
services.AddTransient<IService, MyService>();

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7. What is the difference between abstract class and interface?

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8. What is LINQ, and how does it work?

• LINQ (Language-Integrated Query): Enables querying data in a type-safe and concise way using query syntax or method syntax.
• Example:

var numbers = new List<int> { 1, 2, 3, 4, 5 };
var evenNumbers = numbers.Where(n => n % 2 == 0).ToList();

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9. What are delegates in C#?

• Definition: Delegates are type-safe pointers to methods.
• Usage: Useful for implementing callbacks and event handling.

Example:

public delegate void PrintDelegate(string message);

void PrintMessage(string message) => Console.WriteLine(message);

PrintDelegate del = PrintMessage;
del("Hello, Delegates!");

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10. What are the different types of assemblies in .NET?

• Private Assembly: Used by a single application.
• Shared Assembly: Shared across multiple applications (stored in the Global Assembly Cache - GAC).
• Satellite Assembly: Used for localization/globalization.

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If you need additional questions or in-depth explanations, let me know!