Inheritance and Polymorphism in OOP

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Questions and Answers

What term describes when a derived class provides a specific implementation of a method already defined in its base class?

Overriding (correct)

Hiding

Overloading

Shadowing

Which type of method cannot be overridden when inherited?

Abstract method

Static method (correct)

Protected method

Virtual method

In the context of extension methods, what must the first parameter specify?

Value type

Nullable type

Reference type

The type to which the method applies (correct)

Which access modifier allows access to members only from the class itself and not from derived classes?

Private Signup and view all the answers

What method type is typically used to provide a mechanism for different implementations in derived classes?

Overriding Signup and view all the answers

What must a virtual method not be classified as?

Static Signup and view all the answers

Which method allows extending existing types with additional functionality without changing their source code?

Using extension methods Signup and view all the answers

Which method is defined in a static class that cannot be instantiated?

Extension method Signup and view all the answers

What is a key purpose of using the params keyword in method definitions?

To enable methods to accept a variable number of arguments Signup and view all the answers

Which of the following statements about method overloading is correct?

Method overloading requires different parameter types or number of parameters Signup and view all the answers

Which of the following scenarios would most likely throw an ArgumentException?

When a user provides arguments that do not meet method specifications Signup and view all the answers

Which statement is true regarding method parameters when using the ref or out modifier?

Ref or out modifiers can be used with params arrays Signup and view all the answers

Why can't the following method definitions coexist: public static int Min(int[] paramList) and public static int Min(params int[] paramList)?

Overloading based solely on the inclusion of the params keyword is disallowed Signup and view all the answers

In the context of inheritance, which of these options captures what method overriding allows?

Providing a new implementation of a base class method in a derived class Signup and view all the answers

Garbage collection primarily handles which of the following?

Automatic memory management for unused objects Signup and view all the answers

What will happen if a method is defined to take multiple value types, but is called with a reference type?

A compile-time error will occur due to type mismatch Signup and view all the answers

What is the main purpose of inheritance in object-oriented programming?

To reduce code repetition Signup and view all the answers

In C#, what happens if a derived class does not call a base-class constructor?

The default constructor of the base class is called automatically Signup and view all the answers

Which keyword is used in C# to explicitly call a base-class constructor?

base Signup and view all the answers

Which of the following statements is correct regarding destructors in C#?

Destructors cannot be inherited Signup and view all the answers

Which of the following types can inherit from a class in C#?

Classes only Signup and view all the answers

What is the function of garbage collection in C#?

To prevent memory leaks by reclaiming unused memory Signup and view all the answers

What is a characteristic of method overriding in C#?

The derived method must have the same signature as the base method Signup and view all the answers

Which class is the root of all classes in C#?

System.Object Signup and view all the answers

Study Notes

Object-Oriented Programming Concepts

A method in a derived class that has the same signature as a base class method hides the base method.
A method intended to be overridden is referred to as a virtual method.
Overriding is the mechanism that allows derived classes to provide different implementations of the same method.
A virtual method cannot be private; it must be accessible to allow overriding.
The signature of virtual and override methods must match exactly in both name and parameters.

Access Modifiers

The protected access modifier allows access to class members from the class itself and derived classes.
To extend a type quickly without impacting existing code, utilize extension methods.
Extension methods are defined in a static class and allow adding static methods to existing types.
The first parameter of an extension method must specify the type to which the method applies.

Interfaces and Abstract Classes

An interface does not contain any implementation; it specifies the methods and properties that implementing classes must fulfill.
Interfaces provide a way to separate method signatures from their implementations.
Both interfaces and abstract classes share similarities in defining methods that must be implemented.

Inheritance

Inheritance helps avoid code repetition by allowing classes with common features to relate through a parent-child relationship.
In C#, inheritance is a relationship between classes and can only apply to classes, not structures.
Use the class DerivedClass : BaseClass {...} syntax for defining derived classes in C#.
C# inheritance is always implicitly public, meaning it allows access unless specified otherwise.

Constructors and Base Class Calls

Initialization of fields within a class is performed in a constructor.
The base keyword is used to call a base class constructor in derived classes.
If a derived class does not explicitly call a base class constructor, the compiler automatically calls the base class’s default constructor.

Method Overloading and Variadic Methods

Overloading occurs when multiple methods share the same name but differ in parameters.
A variadic method accepts a variable number of arguments, allowing for flexible method calls.
The ArgumentException class is used to handle illegal arguments supplied to methods.
The params keyword cannot be used with multidimensional arrays, and overloads cannot solely rely on the params keyword.

Method Calls and Validations

Specifying the ref or out modifier with params arrays is not allowed.
Methods cannot share the same name and differ only by using the params keyword in different contexts if combined with ref or out.
Valid calls to a method with params include multiple argument entries, but using unsupported types or formats may lead to compilation errors.

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Description

Test your knowledge on the concepts of inheritance and polymorphism in Object-Oriented Programming. This quiz covers method overriding, hiding, and the usage of virtual methods in class design. Perfect for students learning about OOP principles.