C Sharp Interview Questions

What is C#?
C#, also known as C Sharp is an object-oriented programming langauge that has certain characteristics such as type safe and managed language that is compiled by .Net framework to generate Microsoft Intermediate language.
What are the main principles of Object-Oriented Programming that C# supports?
The four main OOP principles that C# supports are:
Encapsulation (binding data and methods together)
Inheritance (deriving new classes from existing ones)
Polymorphism (objects behaving differently based on data type)
Abstraction (hiding complex implementation details)
What is the difference between Value Types and Reference Types in C#?
Value types store the actual data value within its own memory allocation, like int, float, bool, etc. Reference types store a reference or pointer to the actual object's location in memory, such as strings, arrays, custom classes.
Explain the purpose of the 'using' keyword in C#.
The 'using' keyword has two main uses:
To import .NET namespaces into C# code files
To implement IDisposable and ensure safe use and clean up of unmanaged resources
What are Delegates in C#? Provide an example.
Delegates are type-safe, object-oriented function pointers in C#. They allow methods to be passed as parameters, stored in variables and invoked as needed.
Example: public delegate void PrintMessage(string msg);
What is the difference between static and non-static classes in C#?
A non-static class requires instantiation of an object to access its members. A static class cannot be instantiated and all its members must be static. It is designed to be used without creating instances.
What is an Interface in C#? How does it differ from an Abstract class?
An interface defines a contract of properties, methods and events that a class must implement. Unlike abstract classes, interfaces cannot have access modifiers and cannot contain implementation code. Classes can implement multiple interfaces.
What are Generics in C#? How are they useful?
Generics allow you to define type-safe, re-usable classes and methods that can work with any data type, rather than being specific to only one data type. This maximizes code reusability and type safety.
What do you understand by the term 'Exception Handling' in C#?
Exception handling is a mechanism to handle and recover from runtime errors in C# code. It uses try/catch/finally blocks to catch exceptions, take alternate actions and properly dispose resources in case of errors.
Name some of the most commonly used data structures in C#.
Some of the key data structures are:
Arrays (fixed and resizable)
Lists
Dictionaries/HashTables
Stacks
Queues
LinkedLists
Trees
HashSets