Question

Fill in the blanks in each of the following statements: a. _______ is a form of software reuse in which new classes absorb the data and behaviors of existing classes and embellish these classes with new capabilities. b. A base class's _______ members can be accessed only in the base- class definition or in derived-class definitions. c. \(\ln a(n)\) _______ relationship, an object of a derived class also can be treated as an object of its base class. d. \(\ln a(n)\) _______relationship, a class object has one or more objects of other classes as members. e. In single inheritance, a class exists in a(n) _______ relationship with its derived classes. f. A base class's _______ members are accessible within that base class and anywhere that the program has a handle to an object of that base class or to an object of one of its derived classes. g. \(A\) base class's protected access members have a level of protection between those of public and _______ access. h. \(C++\) provides for _______ which allows a derived class to inherit from many base classes, even if these base classes are unrelated. i. When an object of a derived class is instantiated, the base class's _______ is called implicitly or explicitly to do any necessary initialization of the base-class data members in the derived-class object. J. When deriving a class from a base class with public inheritance, public members of the base class become _______ members of the derived class, and protected members of the base class become _______ members of the derived class. k. When deriving a class from a base class with protected inheritance, public members of the base class become _______ members of the derived class, and protected members of the base class become _______ members of the derived class.

Short answer

a. inheritance, b. protected, c. is-a, d. has-a, e. is-a, f. public, g. private, h. multiple inheritance, i. constructor, j. public, protected, k. protected, protected.

Step-by-step solution

Understanding the Context for Software Reuse

For the first blank, we need to identify the concept where new classes extend or embellish existing classes. In object-oriented programming, this is known as 'inheritance', whereby new classes (derived classes) absorb data and behaviors from existing classes (base classes), adding new functionalities.

Access Level of Base Class Members

The second blank concerns members of a base class that have restricted accessibility. These members are known as 'protected' members, which can be accessed within the base class and its derived classes.

Derived-Class Object Treated as Base-Class

For the third blank, we describe a relationship where a derived class object is recognized as an instance of its base class. This scenario fits the 'is-a' relationship commonly associated with inheritance hierarchies.

Components in Class Composition

The fourth blank describes a relationship wherein a class contains other class objects as members, known as an 'has-a' relationship, often referring to 'composition'.

Relationship in Single Inheritance

In the fifth blank, single inheritance creates an 'is-a' relationship between classes and their derived classes, meaning derived classes inherit properties from a single base class.

Accessibility with Base Class Objects

The sixth blank refers to 'public' members of the base class, which are accessible both within the base class and wherever an object of the base or derived class is accessible in the program.

Intermediate Level of Protection

In the seventh blank, the protection level between public and private is 'protected', providing a moderate level of access control to class members.

Multiple Inheritance Mechanism

The eighth blank refers to 'multiple inheritance', which lets a derived class inherit from more than one base class.

Base Class Initialization When Derived Object Created

For the ninth blank, 'constructor' is the method called implicitly or explicitly to initialize base class data within a newly created derived object.

Public Inheritance and Member Visibility

In the tenth blank "J", public members of a base class remain 'public' in derived classes, and protected members remain 'protected'.

Protected Inheritance and Member Visibility

In the eleventh blank "K", under protected inheritance, both public and protected members of a base class become 'protected' members of the derived class.

Key concepts

Inheritance

Inheritance is one of the core principles of object-oriented programming that allows new classes, called derived classes, to absorb the attributes and behaviors of existing classes, known as base classes. This process is often summarized with the term "is-a" relationship, where the derived class "is a" specialized version of the base class.

This enables code reuse, reducing redundancy in your programs. Imagine having a generic class `Animal`, and from this, you can inherit to create more specific classes like `Dog` or `Cat`. These new classes automatically possess the fields and methods of `Animal`, and you can also extend them with more specific features or override existing ones.

• **Single Inheritance**: A derived class inherits from one base class. This straightforward structure maintains a clean hierarchy.
• **Multiple Inheritance**: A derived class inherits from multiple base classes. This allows for a greater combination of features but can also lead to complexity.

Access Specifiers

Access specifiers in object-oriented programming control the visibility of class members, determining where they can be accessed from.

There are three main levels of access specifiers, each providing progressively stricter access control:

• **Public**: Members declared as public can be accessed anywhere in the program. This is useful for functions or variables that need to be widely accessible.
• **Protected**: Protected members can be accessed within their own class and by derived classes. This sets an intermediate level of visibility, ensuring internal class structures are guarded yet extendable.
• **Private**: These members are accessible only within the class they are declared. They ensure that sensitive class data or functions are hidden from outside manipulation.

Using these specifiers strategically, developers can ensure that class internals remain safe from inadvertent misuse, and at the same time, expose the necessary parts for interaction.

Class Relationships

Class relationships describe how classes in object-oriented programming interact and relate to one another. The primary types of relationships help define how objects communicate within the system, ensuring cohesion and decoupling where necessary.

• **Inheritance (Is-a Relationship)**: Explained previously, this relationship allows a derived class to inherit the features of a base class, enabling polymorphism where a derived class object can be used in place of a base class object.
• **Composition (Has-a Relationship)**: A class can contain objects of other classes, indicating that it "has" certain features. For example, a `Car` class can "have" a `Engine` class as a part of its components. This emphasizes a part-whole relationship, where parts don't exist independently of the whole.

Understanding and properly implementing these relationships help create a well-structured and manageable codebase. They allow developers to build modular and scalable software systems that can evolve over time.