C# Interview Questions

Modern, object-oriented, general-purpose programming language C# is pronounced "C sharp." The European Computer Manufacturers Association (ECMA) and the International Standards Organization both gave their approval for its development by Microsoft under the direction of Anders Hejlsberg and his team within the.Net initiative (ISO). Version 7.2 of C#, one of the language families for Common Language Infrastructure, is currently available. For users who are familiar with C, C++, or Java, C# is simple because its syntax is very similar to that of Java.

Before we dive into the interview questions, let us understand certain prominent features of C sharp.

• Simple to learn: Because C# is a high-level language, it is more similar to other well-known programming languages like C, C++, and Java and is therefore simple for anyone to learn.
• Frequently used for creating desktop and web applications: C# is frequently used for creating desktop and web applications. It is among the most widely used languages on business desktops. C# is the language of choice for anyone looking to develop Microsoft applications.
• Community: The larger the community, the better, as new software and tools will be created to improve it. Due to the sizeable C# Community advancements are made to keep the language alive and prevent its extinction.
• Game Development: A lot of games are developed using C#.

For increased grasping and understanding, we have divided the questions into 3 categories:

• For Freshers
• For Experienced
• For FAQ's

Top 10 C# Interview Questions

1. Describe an Object.
2. What is Serialization?
3. What do user control and custom control mean?
4. What does a Partial Class Mean?
5. What are Sealed Classes in C#?
6. What are I/O classes in C#?
7. Mention all benefits of C#
8. Describe the Features of C#.
9. What kinds of Classes are there in C#?
10.  What do C# Generics do?

Top C# Interview Questions for Freshers

1. What is a legacy? Support for Multiple Inheritances in C#?

To inherit something is to take on some of the characteristics of a master class. Multiple inheritances are not supported by C# either. Instead, by using interfaces and the class label in the signature, you can inherit the properties.

2. Describe an Object.

An object is a representation of a class that allows us to access its methods. In order to create an object, use the "New" keyword. The details of the variables, the behavior of a class, and methods that generate an object in memory are contained in that class.

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3. Establish Constructors

A member function with the same name as the class it belongs to is called a function Object(). Every time an object class is created, the function Object() is automatically called. As the class is initialized, the values of the data members are constructed.

4. How do Jagged Arrays work?

The term "jagged array" refers to an array with elements of the type array. The components can come in a variety of shapes and sizes. An array of arrays is another name for the jagged array.

5. What distinguishes the ref and out parameters?

In contrast to out, which does not require initialization prior to actually passing to a method, ref arguments must be initialized before being passed.

6. What does the C# "using" Statements?

The "using" block is used to acquire a resource, use it, and then automatically discard it after the block's execution is complete.

7. What is Serialization?

An object must be transformed into a stream of bytes before it can be transported over a network. Serialization is the process of transforming an object into a stream of bytes. An object must implement the ISerialize Interface in order to be serializable. De-serialization is the process of making an object from a stream of bytes in the opposite direction.

8. Can "this" be used inside a Static Method?

Because static methods can only utilize static variables and methods, we are unable to use "This" in a static method.

9. What makes read-only and constants different from one another?

At compile time, constant variables are declared and initialized. After that, the value cannot be altered. Only when we need to allocate the value at runtime do we use read-only.

10. What do user control and custom control mean?

Controls created as executable (Dlls), or custom controls, are simpler to use and can be added to a toolbox. Web forms can have controls added by dragging and dropping. Attributes can be used during design. Custom controls can be easily added to various applications (If Shared Dlls). Therefore, whether they are private, we can copy the dll to the web application's bin directory, add a reference, and then use them.

User Controls are simple to create and resemble ASP including files in many ways. User controls cannot be dragged and dropped from the toolbox. They have their own code and design. Ascx is the user controls file extension.

11. What distinguishes the class System? String and System.Text.StringBuilder from one another?

System. strings cannot be changed. When we change a string variable's value, new memories are allocated for the modified value, and the old memory allocation is freed up. System. The concept of a mutable string, where a number of operations can be carried out without allocating a separate memory address for the modified string, was incorporated into the design of StringBuilder.

12. What distinguishes the System. Array from other arrays. both System.Array and CopyTo(). Clone() ?

We create a new array object with all the elements from the original Array by using the Clone() method and the CopyTo() method. Copying the entire contents of one existing array into another. Both procedures execute a shallow copy.

try {
    GetAllData();
} 
catch (Exception ex) {
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13. In C#.NET, What do Generics mean?

In order to reduce code duplication, improve type safety, and boost performance, generics are used to create reusable code classes. We can make collection classes with generics. The system will create a generic collection. Collections. Classes like ArrayList in the System should not be used; instead, use a generic namespace. namespace for collections. The use of parameterized types is encouraged by generics.

Related Article: What is .Net FrameWork?

14. List the most frequently encountered exception types in the.net Framework

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

15. How can a nulliparous design pattern be used in C#?

A class that uses the singleton pattern can only contain one instance and offers a universal access point.

Example:

Public sealed class Singleton
{
Private static readonly Singleton _instance = new Singleton();
}

16. How can nullable types be used in.Net?

Value types can accept a null value in addition to their usual values. Nullable types are those kinds of types.

Int? someID = null;
If(someID.HasVAlue)
{
}

17. What Distinguishes the C# "is" and "as" Operators?

The "is" operator is used to determine whether an object is compatible with a particular type, and it goes back to a Boolean answer.

Casting an item to a type or class uses the "as" operator.

18. What makes the direct cast and ctype different from one another?

The entity that necessitates the run-time type to match the based-on factor analysis in DirectCast is converted using DirectCast.

When there is a defined conversion between an expression and a type, Ctype is used.

19. Give final blocks and finalize different names.

The finalize block is invoked after the try-and-catch blocks are finished because it handles exceptions. Regardless of whether the exception was caught, this block of code is executed. This block of code is cleaner overall.

The finalized method is called just before garbage collection. Cleaning up unmanaged code, which would be scheduled to happen when an example is not re-called, is one of the finalized method's top priorities.

20. What does a Partial Class Mean?

A partial class divides the definition of a class into different classes that can be found in the same or different source code files. When a class is created, all of the methods from all of the source files can be made accessible using the same object. A class meaning can be written in multiple files, but it is gathered as a single class at runtime. This is what the word "partial" means.

Top C# Interview Questions For Experienced

1. What are User Control and Customs Control?

Code that has been compiled creates custom controls. These can be added to the toolbox and are simple to use. These controls can be dropped by developers onto one‘s web forms. User Controls and ASP include files are very similar. Furthermore, making them is simple. However, user controls cannot be added to the toolbox. Additionally, they cannot be dropped and dragged from it.

2. What are Sealed Classes in C#?

Sealed classes are formed when a restriction must be positioned on the class that must be inherited. A sealed multiplicative effect is used to avoid any etymology from a class. When an encased class is obtrusively stipulated as a base class, a compile-time error happens.

3. What are Delegates?

In C++, delegates are very similar to function pointers. Delegates are form safe whilst also function pointers are not, which is the only and primary distinction between the two. Because they enable the development of generic type-safe functions, delegates are crucial.

4. What distinguishes Method Overloading from Method Overriding?

When a method is overridden, the appropriate method definition in the derived class is changed, altering the behavior of the method. Method overloading refers to the creation of a method with the same name and class but a different signature.

5. What are C# attributes and what makes them Important?

Developers have the option to describe unambiguous tags on a small number of entities in C#. For instance, attributes include class and method. Reflection can be used to retrieve the information pertaining to the attribute during runtime.

6. What do C# namespaces mean?

You are able to keep a unique set of names by using namespaces. The fact that class names proclaimed in one namespace and another do not conflict is a significant benefit of namespaces.

7. What details can you give me about the C# XSD file?

XSD, or XML Schema Definition, stands for. If there is no XSD file attached to the XML file, it can include any attributes and elements.

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

Multiple classes in the C# System.IO namespace are used to perform various file operations, including creation, deletion, closure, and opening.

9. Describe what C# regular expressions are in detail.

A pattern that can be used to complement a set of inputs is known as a regular expression. It is possible to use constructs, character literals, and operators.

10. Describe the four steps that make up the compilation of C# code.

In C#, code compilation consists of four steps:

• Managed code source code compilation.
• Assembly code is combined with newly written code.
• It has loaded the Common Language Runtime (CLR).
• Executing an assembly is done using CLR. 

11. What are the different ways to pass parameters to a method?

There are several ways to pass parameters in a method, including:

• The method can return multiple values with the help of the output parameters.
• Value parameters allow for the deception of the actual parameter without changing the values of the actual parameter because the finally settled copies and retail locations the value of the actual argument.
• Reference Parameters: Because the formal argument contains the memory location of the actual parameter, any change to the formal argument will also affect the actual argument.

12. Mention all benefits of C#

The benefits of C# are as follows:

• Component-oriented language C#.
• This language is object-oriented.
• The syntax is very simple to understand.
• Learning is made simpler.
• C# is a component of the.NET framework.

13. Mention the key IDEs that Microsoft offers for C# development.

The IDEs listed below are beneficial for C# development:

• MonoDevelop
• Code by Visual Studio (VS Code)
• Visual Studio Express for browsing (VSE)
• Graphical Web Developer (VWD)

14. Describe the Features of C#.

Some of the key characteristics of C# include

• C# is a managed and safely typed language.
• The object-oriented nature of C#.
• Cross-platform compatibility is a strength of C#.
• When it comes to compilation, C# is a language that works on any platform.
• The general purpose nature of C#.
• The implementation of constructors and destructors uses C#.
• A component of the.NET framework is C#.
• Languages like C# are simple to grasp and learn.
• A structured language is C#.

Frequently Asked C# Interview Questions

1. What distinguishes C# from C?

You would be familiar with C as the procedural language and C# as being more object-oriented. The main distinction is that C# and C does not support Common Language Runtime's (CLR) automatic garbage collection. .NET is primarily required for C# to run, whereas C is a platform-independent language.

2. What is Common Language Runtime (CLR)?

CLR manages C# program execution among other languages. garbage collection, security handling, and Memory management are all handled by the CLR architecture, which resembles

3. What is C# Garbage Collection?

The process of cleaning up memory that has been occupied by unwanted objects is known as garbage collection. A certain amount of memory is automatically assigned to a class object when it is created in the heap memory. Now that you've finished working on the object, the storage device it once occupied is wasted. Memory needs to be freed up. In three situations, garbage collection takes place:

• If the objects' combined memory usage goes over a certain threshold.
• Upon calling the trash collection method
• If your computer has insufficient physical memory

4. What kinds of Classes are there in C#?

A class is a thing that unifies all the characteristics of its objects and instances under one umbrella. These classes come in four varieties in C#:

• Static class: A static class is one that forbids inheritance and is defined by the word "static." As a result, it is impossible to generate an item for a static class.
• Limited class: The class named "partial" enables its members to divide or start sharing source (.cs) files in portions.
• Abstract class: classes that are unable to be implemented where objects cannot be created are known as abstract classes. The OOPS concept of abstraction is used by abstract classes. The use of abstraction makes it easier to extract crucial details and conceal irrelevant ones.
• Sealed class: Classes that can't be inherited are known as sealed classes. Utilize the word to restrict access.

5. How do manage and unmanaged codes differ?

With managed code, you can use the.NET framework's managed CLR runtime environment. Rather than the operating system itself, it managed code runners on the controlled runtime environment.

Benefits: Offers a range of services, including exception handling and garbage collection.

Unmanaged code is code that operates independently of the.NET framework and does not run on the CLR.

Benefits: They operate without high-level languages because they don't offer their services.

6. What distinguishes an Interface from an Abstract Class?

Let's examine how an abstract data type and an interface differ from one another

• Classes that aren't instantiated, or that cannot produce an object, are called abstract classes. Because every method inside the interface is an abstract method, it functions similarly to an abstract class.
• Surprisingly, while an interface's methods are all abstract, abstract classes can include both non-abstract and abstract methods.
• We must use the Abstract keyword to proclaim abstract methods because abstract classes can contain all abstract and non-abstract methods. However, there's no such need in the interface.
• While an interface lacks constructors, an abstract class does.

Related Article: .NET Libraries

7. What distinguishes out Keywords from ref Keywords?

• Using references rather than values, C# ref keywords pass arguments. You must expressly mention "ref" in order to use it.
• Within methods and functions, C# out search terms pass arguments.
• The "out" keyword is employed to pass references for arguments to methods that return multiple values. Despite being identical to the ref keyword, it must first be the initial state before it can be passed. When we want to return the value in the same factors that are passed as arguments, the out as well as ref keywords come in handy.

8. What are C# Extension Methods?

Extension techniques enable the addition of new techniques to already-existing ones. Static methods have been added. When you want to add methodologies to an existing class but don't have the authority to do so, you can occasionally create a new static class that contains those new methods. Bind this class to the existing one once the extended methods have been declared to see how the methodologies will be added to the current class.

9. What do C# Generics do?

The fundamental principle of type-safety in C# is compromised because defining any type of object is considered okay in collections. Generics were therefore added to the code to type-safe it by allowing reuse of the data processing algorithms. Generics in C# denotes a lack of connection to any particular data type. The burden of using boxed, unboxed, and typecast objects is lessened by generics. Generic definitions are always enclosed in angular brackets (>). With the following syntax, a generic class can be created:

GenericList<float> list1 = new GenericList<float>();
GenericList<Features> list2 = new GenericList<Features>();
GenericList<Struct> list3 = new GenericList<Struct>();

GenericListfloat> is a cliched class in this instance. Each occurrence of T in the class is replaced at program execution with the type argument for each of these cases of GenericListT>. We have produced 3 distinct type-safe with the same class by substituting the T.

10. What distinguishes an Array from an ArrayList in C#?

An array is a grouping of related variables given a single common name. While an array list is a group of individually indexable objects. You can access a variety of features with ArrayList, including adding, searching, and sorting items in the ArrayList as well as dynamic memory allocation.

• The shared memory is fixed when an array is declared because the dimensions of the items are fixed. However, it can be dynamically increased or decreased with an ArrayList.
• The system owns the array.
• ArrayList is a member of the system, while an array namespace.
• While all of the goods in an ArrayList can have either the same data type or a different data type, all of the items in an arrangement are all the same data type.

Key Upshots

The functional programming language for all higher-level programming languages is C#. C# developers are all in high demand and have access to rewarding career opportunities in industries like data science, front-end, back-end, and app development. And because Microsoft supports it, C#’s popularity keeps rising.Your career can advance significantly if you learn C#.