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C# Interview Questions by topic

On this page you can see list of all C# Interview Questions by topic. In most of the interviews, these questions are very frequently asked. If you have an question that is asked in a previous interview, please post it here.

Free C# Video Tutorial

What's the difference between IEnumerable and List?

New features in c# 4.0

Give an example for explicit interface implementation

Difference between EXE and DLL

Unit Testing a private static method

Unit Testing a private method

What are the problems of multiple class inheritance.

Difference between an abstract class and an interface

Where did you use delegates in your project


Advantages of Interfaces

Advantages and disadvantages of using generics

What are the advantages and disadvantages of using collection classes present in System.Collections namespace

What are the advantages and disadvantages of using arrays



Partial classes, structs and methods

Nested Types



Methods / Functions




Access Modifiers

Why should you override the ToString() method


Abstract and Sealed class members



Classes and structs

Data Types

Value types and reference types

Data type casting

Boxing and Unboxing


Basic C# Interview Questions on strings



  1. Explain what is override

    1. Override is keyword which is used to override the methods, that are declared as virtual in base class
      ex: Class Base
      Public virtual void M1()
      // Some logic
      Class Child:Base
      Public override void M1()
      // Redefine user logic

  2. What is Reflection in .NET?

  3. Reflection is a mechanism in .NET using which we can dynamically find information about assemblies, modules and types at runtime. In short, reflection is used to inspect assembly, module and types metadata at runtime. Reflection can be used to achieve late binding.

  4. reflection is that which people do when things backfire, blowback, blowup, breakup... i guess u get it... :-)

  5. What do you mean by Generic Class ?

    1. Generics are similar to ―templates in C++.
       Def: A generic is an identifier, which automatically identifies the data type of a variable. This is designed to represent a particular data type, during an object life time or a method execution.

  6. now i m vry cmfrtble wth basics of csharp thanks alot venkat it helped me sersly

  7. Awesome blog for last moment revision

  8. Thanks a lot. You are a great help

  9. Sir, Thank you very much, please post some videos on

  10. Sir,ur videos are nice. please upload the video for Extension method. Thanks in advance. Sukumar M.....

  11. thank you venkat for all efforts you've done, and we expect more

  12. thank you venkat sir. You videos are really good to understand basic concepts. Please post videos on WCF and WPF and design patterns.

  13. How to learn WPF ? Do I need learn C# first ? Is there any good tutorial video for WPF ? Please advise.

  14. Your Videos are great and educational. Can you do Questions or Exercises for each C# lessons if you have the time and a video where explain how to program a whole project. Thank you in advance.

  15. Hi Venkat,
    Your Videos are great and helped to understand .net Framework in deep.

    I do not understand the proper procedure to use the DLL assembly in Excel which was created in Visual Studio2010 . Let me explain what I am doing.

    I created an assembly ThermoData in Visual Studio with its classes as COM visible. Similarly, I created a demonstration program, Demo (windows App) with using the assembly. So, when I install the demonstration program on a machine, the assembly gets registered automatically.

    I can use the assembly in Excel with making the reference to ThermoData.tlb. It works perfectly.

    Now, I created another workbook. I followed the same procedure of referencing the library. It does not work. Of course, the Intellisence in Excel sees all the properties and methods of the assembly. But when I run the excel function in a Worksheet, it does not work. Similarly, it stops working in the first excel workbook, too.

    If I create another assembly with other name, it works again but with same problem.

    I will appreciate your help to resolve it. Similarly, I would like to read more on DLL and TLB.

    Best regards


  16. why to use interface when the same can be achieved by using abstract class or base class. Explain with example?

  17. Hi Venkat ,
    Your videos are excellent training material . Can we have a video on serialization .

  18. Hi
    I have some interview questions, venkat i request you please record the videos in simple terms , i would like to hear when you explain these in simple terms.

    1.what is the different between private constructor and static constructor.
    2.what is destructor, finalize, and dispose() to restrcit the wcf methods to only specific users.
    4.what is the difference between gridivew and datagrid.

    Thanks in advance.

  19. Hi Venkat ,
    I have some Question that is asked one month ago pleased record it.
    1. what is covariant and contravariant? why we used.
    2. How Entity Frame Work support multiple databases.
    3. How to implement ThreadPooling and when.

  20. how we can print ..
    * * *
    * *
    if an array contain [1,2,4]

  21. What are the advantages of using static class in

  22. Hi Venkat

    Currently I am working in HCL and Yesterday, I had an interview in Microsoft. Unfortunately, I could not clear it. As I am going through Venkat Series so I know one day I will definitely clear it.

    Please do a favor if you can add below topics in your series, I could not find it. May be it comes later in your videos, as I am going through it one by one.
    1. there were two questions on Binary Search Tree which I could not understand. One question was like there was tree and what is the type of this tree.
    2. Also there was a question on Dynamic binding, now I come to know that it is actually method Overriding concept. But I could not understand in your C# series. Please add these things in your series.
    3. How CLR is configured.
    4. How to keep an object always alive.


  23. what is the advantage of method hiding?

  24. I have been asked a question, Would you or would you rather not use "Static Class" to achieve a single instance purpose instead of using Singleton Design Pattern ?

  25. Hello Everyone,

    in most of the interviews(Tcs,Broadridge) asking about multiple inheritence.

    when we say its not possible to create in .net but we can achieve the same using interfaces.

    next cross question by interviewer

    intead of interfaces cant we make use of abstract classes ?and can go with multiple inhertence?

    cant say anything.

    its oops concept can anybody suggest me to clear on this.


  26. HI venkat..
    I had faced a question in an interview...
    why we need to publish our website...?

    is there any special reason...?

    Answer me As soon as possible....

  27. Hello:

    i have a questions about from print in web form.
    i have an gridview with SqlDataSource and i need a buttom for print the data but i can´t
    can you help me please.
    my code is:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web;
    using System.Web.UI;
    using System.IO;
    using System.Text;
    using System.Configuration;
    using System.Web.UI.WebControls;
    using System.Drawing.Printing;

    public partial class Fallas : System.Web.UI.Page
    protected void Page_Load(object sender, EventArgs e)
    Proxy.Operaciones servicio = new Proxy.Operaciones();
    Proxy.Usuario Objeto = new Proxy.Usuario();
    string userid = (string)Session["Userid"];
    if (userid == "" || userid == null)

    protected void Volver_Click(object sender, EventArgs e)
    String testfalla = (string)Session["reportefallas"];

    if (testfalla == null)
    protected void Salir_Click(object sender, EventArgs e)

    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)

    protected void Imprimir_Click(object sender, EventArgs e)

    catch (Exception ex)
    Label1.Text = ex.ToString();
    Label1.Visible = true;


    Best Regards

  28. Write a C# console application which builds a single list of vehicles from any appropriate source and then prints the details of all the vehicles in the list out to the console. A vehicle can be one of 3 types: Car, Motorbike, Boat All 3 types have the following, common properties: Engine, Manufacturer, Model Each vehicle also has properties which are unique to each vehicle type. For example, a car has 4 wheels, a motorbike has 2 and a boat has a propeller

    Should i use Enum For car manifacturer if yes how can i do so with properties?
    Should i make the base class as an abstract Class?
    Should i override My properties?
    Should i use Interfaces or properties for Engine ?
    Can someone please provide a code sample, i would be very thankful

  29. how to create a table under stored procedure and insert data into created table through stored procedure in

  30. Hi Venkat,
    Your are doing great work, I have been using your tutorial for one month, I am glad to see your tutorials and I am winforms application developer, Can you upload some winforms and WPF tutorials?
    Your videos are very clean and understandable.
    Thanks for sharing these types of tutorials.

  31. how to make organization chart using C# or

  32. hi venkat, can you please explain how to handle concurrency issue in a web application ?


If you are aware of any other C# questions asked in an interview, please post them below. If you find anything missing or wrong, please feel free to correct by submitting the form below.

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