.Net Top 50 Interview Questions

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C# Interview Questions and Answers

Here are C# interview questions and answers for fresher as well 5 or 10 years experienced candidates to get their dream job.

1) What is the role of C#?

Sample answer:

The role of C# as a programming language is to precisely define a set of operations that a computer can perform to complete a task. It’s used to create desktop apps, mobile apps, web apps, websites, and web services.

2) What is meant by object-oriented programming?

Sample answer:

Object-oriented programming (OOP) is an approach to programming where software is primarily designed by using objects (essentially data) that interact with each other. 

When different pieces of data are put together, they come to form the software as a whole. OOP is an alternative to functional or procedural programming and it’s also the approach used by C#.

3) Can multiple catch blocks be executed?

No, Multiple catch blocks of similar type can’t be executed. Once the proper catch code executed, the control is transferred to the finally block, and then the code that follows the finally block gets executed.

4) What is the difference between public, static, and void?

Public declared variables or methods are accessible anywhere in the application. Static declared variables or methods are globally accessible without creating an instance of the class. Static member are by default not globally accessible it depends upon the type of access modified used. The compiler stores the address of the method as the entry point and uses this information to begin execution before any objects are created. And Void is a type modifier that states that the method or variable does not return any value.

C# interview questions

7) What is Jagged Arrays?

The Array which has elements of type array is called jagged Array. The elements can be of different dimensions and sizes. We can also call jagged Array as an Array of arrays.

8) What is the difference between ref & out parameters?

An argument passed as ref must be initialized before passing to the method whereas out parameter needs not to be initialized before passing to a method.

9) What is the use of ‘using’ statement in C#?

The ‘using’ block is used to obtain a resource and process it and then automatically dispose of when the execution of the block completed.

11) Can we use “this” command within a static method?

We can’t use ‘This’ in a static method because we can only use static variables/methods in a static method.

12) What is the difference between constants and read-only?

Constant variables are declared and initialized at compile time. The value can’t be changed afterward. Read-only is used only when we want to assign the value at run


18) What is the difference between Array and Arraylist?

In an array, we can have items of the same type only. The size of the array is fixed when compared. To an arraylist is similar to an array, but it doesn’t have a fixed size.

19) Can a private virtual method can be overridden?

No, because they are not accessible outside the class.

20) Describe the accessibility modifier “protected internal”.

Protected Internal variables/methods are accessible within the same assembly and also from the classes that are derived from this parent class.

23) How can we sort the elements of the Array in descending order?

Using Sort() methods followed by Reverse() method.

25) What’s the difference between an interface and abstract class?

Interfaces have all the methods having only declaration but no definition. In an abstract class, we can have some concrete methods. In an interface class, all the methods are public. An abstract class may have private methods.

26) What is the difference between Finalize() and Dispose() methods?

Dispose() is called when we want for an object to release any unmanaged resources with them. On the other hand, Finalize() is used for the same purpose, but it doesn’t assure the garbage collection of an object.

27) What are circular references?

Circular reference is situation in which two or more resources are interdependent on each other causes the lock condition and make the resources unusable.

28) What are generics in C#.NET?

Generics are used to make reusable code classes to decrease the code redundancy, increase type safety, and performance. Using generics, we can create collection classes. To create generic collection, System.Collections.Generic namespace should be used instead of classes such as ArrayList in the System.Collections namespace. Generics promotes the usage of parameterized types.

29) What is an object pool in .NET?

An object pool is a container having objects ready to be used. It tracks the object that is currently in use, total number of objects in the pool. This reduces the overhead of creating and re-creating objects.

30) List down the commonly used types of exceptions in .net

ArgumentException, ArgumentNullException, ArgumentOutOfRangeException, ArithmeticException, DivideByZeroException ,OverflowException, IndexOutOfRangeException, InvalidCastException, InvalidOperationException, IOEndOfStreamException , NullReferenceException, OutOfMemoryException, StackOverflowException etc.

35) What is the difference between method overriding and method overloading?

In method overriding, we change the method definition in the derived class that changes the method behavior. Method overloading is creating a method with the same name within the same class having different signatures.

36) What are the different ways a method can be overloaded?

Methods can be overloaded using different data types for a parameter, different order of parameters, and different number of parameters.

37) Why can’t you specify the accessibility modifier for methods inside the interface?

In an interface, we have virtual methods that do not have method definition. All the methods are there to be overridden in the derived class. That’s why they all are public.

38) How can we set the class to be inherited, but prevent the method from being over-ridden?

Declare the class as public and make the method sealed to prevent it from being overridden.

39) What happens if the inherited interfaces have conflicting method names?

Implement is up to you as the method is inside your own class. There might be a problem when the methods from different interfaces expect different data, but as far as compiler cares you’re okay.

40) What is the difference between a Struct and a Class?

Structs are value-type variables, and classes are reference types. Structs stored on the Stack causes additional overhead but faster retrieval. Structs cannot be inherited.

41) How to use nullable types in .Net?

Value types can take either their normal values or a null value. Such types are called nullable types.

Int? someID = null;




42) How we can create an array with non-default values?

We can create an array with non-default values using Enumerable.Repeat.

43) What is difference between “is” and “as” operators in c#?

“is” operator is used to check the compatibility of an object with a given type, and it returns the result as Boolean.

“as” operator is used for casting of an object to a type or a class.

44) What’s a multicast delegate?

A delegate having multiple handlers assigned to it is called multicast delegate. Each handler is assigned to a method.

45) What are indexers in C# .NET?

Indexers are known as smart arrays in C#. It allows the instances of a class to be indexed in the same way as an array.


public int this[int index]    // Indexer declaration

46) What is difference between the “throw” and “throw ex” in .NET?

“Throw” statement preserves original error stack whereas “throw ex” have the stack trace from their throw point. It is always advised to use “throw” because it provides more accurate error information.

47) What are C# attributes and its significance?

C# provides developers a way to define declarative tags on certain entities, eg. Class, method, etc. are called attributes. The attribute’s information can be retrieved at runtime using Reflection.

48) How to implement a singleton design pattern in C#?

In a singleton pattern, a class can only have one instance and provides an access point to it globally.


Public sealed class Singleton


Private static readonly Singleton _instance = new Singleton();


49) What is the difference between directcast and ctype?

DirectCast is used to convert the type of object that requires the run-time type to be the same as the specified type in DirectCast.

Ctype is used for conversion where the conversion is defined between the expression and the type.

50) Is C# code is managed or unmanaged code?

C# is managed code because Common language runtime can compile C# code to Intermediate language.

52) Give an example of removing an element from the queue

The dequeue method is used to remove an element from the queue.

using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace DemoApplication


 class Program


  static void Main(string[] args)


   Queue qt = new Queue();




   foreach (Object obj in qt)




    Console.WriteLine(); Console.WriteLine();

    Console.WriteLine(“The number of elements in the Queue ” + qt.Count);

    Console.WriteLine(“Does the Queue contain ” + qt.Contains(3));





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