Chapter 9 Object Orientation: classes based inheritance

• What is class-based inheritance in object-oriented programming?

  It is a feature that allows new classes to reuse, extend, and modify behavior defined in other classes.
• What is the difference between a base class and a derived class?

  The base class is the class whose members are inherited, while the derived class is the class that inherits those members.
• What does it mean that inheritance is transitive?

  If ClassC is derived from ClassB, and ClassB is derived from ClassA, then ClassC inherits members from both ClassB and ClassA.
• What are the alternative terms for base class and derived class?

  Base class is also called the parent class, and derived class is called the child class.
• What happens if class B inherits from class A?

  Every instance of class B is also an instance of class A.
• Why is it beneficial to have a Weapon class inherit from an Item class?

  It allows the Weapon class to reuse the logic defined in the Item class, promoting code efficiency.

  
• What is the purpose of the base keyword in a derived class constructor?

  The base keyword is used to call the constructor of the base class from the derived class constructor.
• What members are not inherited by a derived class?

  Constructors and finalizers are not inherited by a derived class.
• Can a derived class remove inherited members?

  No, a derived class cannot remove inherited members or change their access modifier to a more restrictive one.
• What happens if no base class constructor is explicitly called in a derived class?

  The base class constructor without arguments is called implicitly.
• What does the protected keyword do in C#?

  The protected keyword makes a member accessible to the defining class and its derived classes.
• What is the purpose of the override keyword in C#?

  The override keyword allows a derived class to replace the base class logic with new logic for an inherited method.
• What is System.Object in C#?

  System.Object is the root of the type system in C#, and every class inherits directly or indirectly from it.
• What happens when a class does not explicitly specify a base class?

  The class implicitly inherits from System.Object.
• Why is the ToString method important in System.Object?

  It provides a text representation of an object, which is useful in many situations.
• What conditions must be met to override a method in a child class?

  The parent class must define the method as virtual, and the child class must use the keyword override.
• What are the key concepts of class-based inheritance?

  • Inheritance allows for code reuse and specialization.
  • Base class members can be inherited by derived classes.
  • Constructors are not inherited, but can be called using the base keyword.
  • The protected keyword allows access to derived classes.
  • The override keyword enables method replacement in derived classes.
• What are the implications of using inheritance in object-oriented programming?

  • Promotes code reuse and reduces redundancy.
  • Allows for polymorphism and dynamic method resolution.
  • Can lead to complex hierarchies if not managed properly.
  • May introduce tight coupling between classes.
• What are the differences between hiding and overriding methods?

  • Hiding: Uses the keyword new; does not require the base method to be virtual.
  • Overriding: Uses the keyword override; requires the base method to be virtual.
  • Hiding creates a new method, while overriding replaces the base method logic.
• What is the role of the base keyword in derived classes?

  • Calls the constructor of the base class.
  • Allows access to base class methods and properties.
  • Facilitates method overriding by referencing the base class implementation.
• What are the consequences of not having a parameterless constructor in the base class?

  • Derived classes cannot be instantiated without explicitly calling a base class constructor.
  • If no accessible parameterless constructor exists, it generates a compiler error.
  • The default constructor is added by the compiler only if no constructors are defined in the class.
• What class does Student inherit from?

  Person
• What is the purpose of the private set in the FirstName property of the Person class?

  It restricts the modification of FirstName to within the class only
• What does the constructor of the Person class initialize?

  FirstName and LastName
• What does the ToString method in the Person class return?

  LastName, FirstName ( Person )
• What is the return type of the ToText1 method in the Person class?

  string
• How does the Student class's constructor differ from the Person class's constructor?

  The Student constructor also initializes MajorName
• What does the new keyword indicate in the ToString method of the Student class?

  It hides the inherited ToString method from the Person class
• What happens when a Student object is accessed through a Person reference?

  It uses the ToString implementation from the Person class
• What is the consequence of not using the override keyword in the Student class's ToString method?

  It hides the method instead of overriding it
• What does the sealed keyword do when applied to a class?

  It prevents the class from being inherited
• What does the abstract keyword indicate when applied to a method?

  It indicates that the method has no body and must be implemented in derived classes
• Can an abstract class be instantiated directly?

  No, it cannot be instantiated directly
• What is polymorphism in the context of object-oriented programming?

  It allows an object to be assigned to references of different types

  
• What is the purpose of the is operator in type checking?

  It checks if a value can be assigned to a reference of a type
• What happens if a child class does not implement all abstract methods?

  The child class must also be defined as abstract
• How does the as operator differ from the is operator?

  The as operator attempts to cast and returns null if it fails
• What is the purpose of the OfType method in LINQ?

  It filters a collection to include only elements of a specified type
• What are the consequences of using composition vs inheritance in code reuse?

  • Both can be done right or wrong
  • Inheritance can lead to issues like the Circle-ellipse problem
  • Composition is often preferred for flexibility
  • Unity scripts inherit from MonoBehaviour, showing a mixed approach
• What is the strategy pattern in programming?

  • A design pattern that allows selecting an algorithm at runtime
  • Involves defining a common interface for different algorithms
  • Enables different implementations to be used interchangeably
  • Reduces the need for conditional logic in code