C# Interview Questions and Answers

                

C# Interview Questions and Answers

In this blog, I am sharing with you some of the interview questions related to C#

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1.   What is OOPS? 

   Object-Oriented Programming (OOPS) is a programming paradigm that uses objects and classes for organizing code. It is based on the principles of abstraction, encapsulation, inheritance, and polymorphism. OOPS allows you to model real-world entities as objects and define their behavior through classes.

2.   Basic Concepts of OOPS with Example: 

   -   Abstraction:   Abstraction involves hiding complex implementation details and showing only the necessary features of an object. For example, a car's interface (steering wheel, pedals) abstracts away the internal engine workings.

   -   Encapsulation:   Encapsulation means bundling data (attributes) and methods (functions) that operate on the data into a single unit called a class. It prevents unauthorized access to an object's data. Example:

     ```python

     class Car:

         def __init__(self, make, model):

             self.make = make

             self.model = model

     ```

   -   Inheritance:   Inheritance allows a class to inherit properties and methods from another class. It promotes code reuse. Example:

     ```python

     class SUV(Car):

         def __init__(self, make, model, capacity):

             super().__init__(make, model)

             self.capacity = capacity

     ```

   -   Polymorphism:   Polymorphism allows objects of different classes to be treated as objects of a common superclass. It enables dynamic method binding and method overriding. Example:

     ```python

     def get_vehicle_info(vehicle):

         print(f"{vehicle.make} {vehicle.model}")

 

     my_car = Car("Toyota", "Camry")

     my_suv = SUV("Ford", "Explorer", 7)

 

     get_vehicle_info(my_car)

     get_vehicle_info(my_suv)

     ``'

3.   What is a class? 

   A class is a blueprint or template for creating objects. It defines the structure (attributes/properties) and behavior (methods/functions) that objects of that class will have. It serves as a prototype for creating multiple objects with similar characteristics.

4.   What is an object? 

   An object is an instance of a class. It is a concrete entity that is created based on the class definition. Objects have their own unique data and can perform actions defined by the class's methods.

5.   Define a constructor/Destructor? 

   -   Constructor:   A constructor is a special method in a class that is automatically called when an object of the class is created. It is used to initialize the object's attributes. In Python, the constructor is named `__init__`.

   -   Destructor:   A destructor is a special method (e.g., `__del__` in Python) that is called when an object is about to be destroyed or deallocated. It is less commonly used in Python since memory management is typically handled by the garbage collector.

6.   What is a virtual function? 

   A virtual function is a function defined in a base class that can be overridden by a derived class. In languages like C++, you use the `virtual` keyword to declare a function as virtual. This allows for dynamic binding, where the appropriate function implementation is determined at runtime based on the actual object type.

7.   What is function overloading? 

   Function overloading is a feature that allows a class to have multiple functions with the same name but different parameters or parameter types. The correct function to call is determined based on the number or type of arguments provided.

8.   What is function overriding? 

   Function overriding occurs when a derived class provides a specific implementation of a function that is already defined in its base class. The overridden method in the derived class should have the same method signature.

9.   What is an abstract class? 

   An abstract class is a class that cannot be instantiated and is meant to be subclassed. It may contain abstract methods (methods without implementation) that must be overridden by any concrete (sub)class.

10.   What is a ternary operator? 

    A ternary operator (also known as the conditional operator) is a shorthand way of writing an `if-else` statement. It has the form `condition ? expression_if_true : expression_if_false`. It evaluates the condition and returns one of the two expressions based on whether the condition is true or false.

11.   What are different types of arguments? 

    In programming, function arguments can be categorized as:

    -   Positional Arguments:   Arguments passed in a fixed order.

    -   Keyword Arguments:   Arguments passed with the parameter name.

    -   Default Arguments:   Arguments with predefined values.

    -   Variable-Length Arguments:   Arguments that allow a variable number of inputs.

12.   What is an interface? 

    An interface is a programming construct that defines a contract specifying a set of methods that a class implementing the interface must provide. It defines what methods a class should have but does not provide the method implementations itself.

13.   What is exception handling? 

    Exception handling is a mechanism to handle runtime errors or exceptional conditions in a program gracefully. It involves catching and handling exceptions (errors) to prevent program crashes and provide meaningful error messages to users.

14.   Difference between overloading and overriding: 

    - Overloading: Multiple methods in the same class with the same name but different parameters.

    - Overriding: A method in a subclass with the same name, return type, and parameters as a method in the superclass.

15.   What are access modifiers? 

    Access modifiers control the visibility and accessibility of class members (attributes and methods). Common access modifiers include `public`, `private`, and `protected`.

16.   What are the various types of constructors? 

    -   Default Constructor:   Takes no arguments and provides default values.

    -   Parameterized Constructor:   Takes one or more arguments to initialize object properties.

    -   Copy Constructor:   Creates a new object as a copy of an existing object.

    -   Static Constructor:   Initializes static members of a class.

17.   Early and late binding: 

    -   Early Binding:   Also known as compile-time binding, it involves resolving method calls at compile time. This is typical in languages like C++ for non-virtual functions.

    -   Late Binding:   Also known as runtime binding, it resolves method calls at runtime based on the actual object type. This is common for virtual functions in languages like C++.

18.   Partial Class 

    A partial class is a feature in some languages (e.g., C#) that allows a class's definition to be split across multiple source files. All partial class parts are combined into a single class definition at compile time.

19.   Static Class 

    A static class is a class that cannot be instantiated and is used to group related methods and properties. It is often used for utility functions and does not have instance-specific state.

20.   Sealed Class 

    A sealed class is a class that cannot be inherited or extended by other classes. It is used to prevent further modification or extension of a class's functionality. In C#, the `sealed` keyword is used to mark a class as sealed.