Top C# Interview Questions and Answers For 2024

C# (C-sharp) is one of the most popular programming languages. It is a high-level language that is user-friendly to learn. Developed in 2000 by Microsoft, it is used for building mobile applications, Windows desktop applications, games, and more. Mastering C# can open a lot of doors of career opportunities for you as a developer. If you are appearing for a C# interview, here are the top C# interview questions for beginners and professionals to help you feel more confident and prepared in your interview.

 

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Top C# Interview Questions and Answers

Q1. What is C# (sharp)?

Ans. C# (sharp) is a high-level, general-purpose, object-oriented programming language. It is organized around objects instead of actions and data instead of logic. It is compiled by the .NET framework to generate Microsoft Intermediate Language. It is used by developers around to world for creating software components.

Q2. What are the features of C# (sharp)?

Ans. The following are some of the key features of C#:

• Simple language with a structured approach
• Supports language interoperability
• Object-oriented programming language
• Type-safe
• Supports many modem features, such as error handling features and modern debugging features
• Scalable
• Component Oriented
• Fast compilation and execution speed
• Has a rich library

Q3. What are the types of classes in C#?

Ans. In C#, a class is a user-defined data type that represents the state and behavior of an object. There are four types of classes in C#:

1. Static class: It does not allow inheritance. It means that we cannot create an object for a static class. It is defined by the keyword ‘static’.
2. Partial class: A partial class allows its members to divide their properties, methods, and events into multiple source files. These files are combined into a single class at the compile time. It is defined by the keyword ‘partial’.
3. Abstract class: Abstract classes are classes that provide a common definition to the subclasses. It is the class whose object is not created. These classes work on the OOPS concept of abstraction.
4. Sealed class: A sealed class cannot be inherited. It is used to restrict the properties. The sealed class uses the keyword ‘sealed’.

Also Read: Top C Programming Interview Questions and Answers

Q4. What are the differences between a struct and a class in C#?

The following are the differences between a struct and a class in C#:

Struct	Class
It is a value type that inherits from System.Value Type	Class is a reference type that inherits from the System.Object Type
Struct can’t be inherited from other types	It can be inherited from other classes
It cannot abstract	Can be an abstract type
A struct can create an instance, with or without a new keyword.	It uses a new keyword for creating instances
Each variable contains its own copy of the data	Two variables can contain the reference of the same object
Used for smaller data	Used for large data

Q5. How does the code gets compiled in C#?

Ans. The code compilation is done in four steps in C#:

• Compile the source code into managed code with the C# compiler.
• Combine the newly created code into assemblies.
• Load the CLR (Common Language Runtime).
• Execute the assembly by CLR.

Q6. What is the difference between “dispose” and “finalize” methods in C#?

Ans. The difference between the dispose() and finalize() methods is that dispose() needs to be explicitly invoked by the user while finalize() can not be called explicitly. It is invoked by the garbage collector. The finalize() method cannot be implemented directly. It can only be implemented using declaring destructor.

Q7. What are I/O classes in C#?

Ans. In C#, there are several classes in the System.IO namespace for performing various tasks such as creating, opening, reading, deleting, and closing a file. Below are some of the commonly used I/O classes in C#:

I/O class	Description
Directory	Manipulates a directory structure
File	Manipulates files
BinaryReader	Used for reading primitive data from a binary stream.
BinaryWriter	To write primitive data in binary format
FileInfo	Performs operations on files
StreamReader	Reads characters from a byte stream
StreamWriter	Writes characters to a stream
StringReader	Used for reading from a string buffer
StringWriter	Used for writing into a string buffer

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Now, let’s take a look at some more C# interview questions.

Q8. What is the syntax for catching an exception in C#?

Ans: We use the try-catch block to catch an exception in C#. Each catch block has an exception type. It can contain additional statements needed to handle that exception type.

try {
//exception handling starts with try block
} catch( ExceptionName e1 ) {
   // errors are handled within the catch block
} catch( ExceptionName e2 ) {
   // more catch block

Q9. What is managed and unmanaged code in C#?

Ans. Managed codes are the codes controlled by the CLR. Managed code is developed in the .NET framework. It runs on the managed runtime environment and offers features such as garbage collector and exception handling.

Unmanaged codes are the parts of the program written using the unsafe keyword. The unmanaged code doesn’t run on CLR. It works outside the .NET framework.

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Q10. Explain boxing and unboxing in C#.

Ans. Boxing and unboxing both enable developers to convert .NET data types from value type to reference type (and vice versa). The process of converting a value type to a reference type is called Boxing whereas unboxing converts a reference type to a value type.

For Example

int num = 17; Object Obj = num;    // boxing int i = (int)Obj;    // unboxing

Q11. What is garbage collection in C#?

Ans. Garbage collection is an automatic memory manager. It process of managing the allocation and release of memory. It manages the allocation and release of memory. Garbage collection recovers the objects that are no longer used, clears their memory, and keeps the memory available for future allocations.

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Q12. What is the delegate in C#?

Ans. A delegate is an object or a reference type variable in C#. It holds the reference to a method.

Q13. Can we override a private virtual method?

Ans. We cannot override a private virtual method as it cannot be accessed outside the class.

Q14. Explain Reflection in C#.

Ans. Reflection allows us to inspect metadata of the types in our program dynamically. It enables us to retrieve information on the loaded assemblies and the types defined in them at runtime. Use System.Reflection namespace in your program to add reflection in the .NET framework and retrieve the type.

Q15. Name the access modifiers and accessibility levels in C#.

Ans. In C#, there are four access modifiers, namely public, private, protected, and internal. The accessibility levels include:

• public
• private
• protected
• internal
• private protected
• protected internal

Q16. Explain Jagged Array.

Ans. In C#, a jagged array is an array that has elements of the array type. The dimensions and sizes of elements can be different.

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Q17. How to sort the elements of the Array in descending order?

Ans. We can use the Sort() method and Reverse() method to sort the elements of the Array in descending order.

Q18. Write a program to reverse a string in C#?

Ans. Below is the program to reverse a string in C#

using System;
namespace Learn
{
class Program
{
static void Main(string[] args)
{
string str = ” “, reverse = ” “;
int Length = 0;
Console.WriteLine(“Enter a String : “);
str = Console.ReadLine();
Length = str.Length – 1;
while(Length>=0)
{
reverse = reverse + str[Length];
Length–;
}
Console.WriteLine(“Reverse string is {0}”,reverse);
Console.ReadLine();
}
}
}

Output

Enter a String : JOHN  Reverse String is NHOJ

Q19. Explain how code gets compiled in C#?

Answer: Following are the 4 steps to compile a code in C#:

• Compile the source code in the managed code compatible with the C# compiler.
• Then, combine the above newly created code into assemblies.
• Load the CLR.
• At last, execute the assembly by CLR, which will produce the output.

Q20. What is the use of ‘using’ statements in C#?

Answer:  It helps to control the usage of one or more resources used within the program. The resources are continuously consumed and released. The main objective of using statement is to manage unused resources and free them automatically. Once the object is created which is using the resource and when you are done you make sure that the object’s disposal method is called to release the resources used by that object, this is where using statements works well.

Q21. How can you check if a number is an Armstrong number or not with C#?

using System;  
  public class ArmstrongDemo  
   {  
     public static void Main(string[] args)  
      {  
       int  n,b,sum=0,num;      
       Console.Write("Enter the Number: ");      
       n= int.Parse(Console.ReadLine());     
       num=n;      
       while(n>0)      
       {      
        b=n%10;      
        sum=sum+(b*b*b);      
        n=n/10;      
       }      
       if(num==sum)      
        Console.Write("An Armstrong Number!");      
       else      
        Console.Write("Not Armstrong Number!");      
      }  
  }

Output:

Conclusion

C# is in high demand in top software companies across the world. Mastering this language and applying for a job related to C# can be one of the best career decisions you can make in 2022.

We hope this article helped you understand the type of C# interview questions you might face in your upcoming interview.

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