Question

In the following line of code, the class access specification for the base class is ________class Pet : public Dos

Short answer

Answer: The class access specification for the base class is public.

Step-by-step solution

Identify the access specifier

To identify the access specifier for the base class, we must look for keywords 'public', 'protected', or 'private' before the base class name. In this case, we can see the keyword 'public' before the base class 'Dos'.

Determine the class access specification for the base class

Based on the analysis, since 'public' is the access specifier present before the base class 'Dos', the class access specification for the base class is public.

Key concepts

Access Specifiers

Access specifiers are an essential part of C++ programming that control the accessibility of members within a class. There are three primary access specifiers in C++: public, protected, and private. Each serves a distinct purpose in determining the visibility and accessibility of class members from outside the class and within derived classes.

Here's a brief overview of each:

• Public: Members declared as public are accessible from any part of the program. This means that they can be accessed by functions or objects outside the class.
• Protected: Protected members are accessible within the class itself and by derived classes. However, they cannot be accessed from outside these classes.
• Private: Private members are only accessible within the class they are declared in. They cannot be accessed by derived classes or any outside code.

In the given exercise, the keyword 'public' is used as the access specifier for the base class 'Dos'. This means that all public members of 'Dos' are accessible by objects and functions outside the derived class 'Pet'.

Public Inheritance

In C++, inheritance is a core feature that allows a class to derive properties and functionality from another class. There are three types of inheritance: public, protected, and private. Each type of inheritance affects the accessibility of the inherited members in different ways.

Public inheritance is the most common type used. When a class is derived publicly from a base class, as represented by the syntax `: public BaseClass`, it implies that:

• Public members of the base class remain public in the derived class.
• Protected members of the base class remain protected in the derived class.
• Private members of the base class are not accessible directly by the derived class.

In the example, `class Pet : public Dos` indicates that 'Pet' inherits from 'Dos' using public inheritance. Therefore, all the public members of 'Dos' are also public members in 'Pet', allowing them to maintain their visibility and accessibility.

Base Class

A base class is a class that provides properties and behaviors to derived classes. Think of it as the foundation or starting point for class hierarchies in object-oriented programming. The base class holds attributes and methods that multiple derived classes can inherit, promoting code reusability and organization.

In a class hierarchy, the base class sits at the top, with derived classes extending its functionality or adding more specific properties and behavior. The concept of a base class is vital in C++ as it dictates how inheritance works, including access control through access specifiers.

In our exercise, 'Dos' is the base class from which 'Pet' is derived. This hierarchical relationship allows 'Pet' to inherit and leverage the functionality defined in 'Dos'. It's important to note that while public members of the base class can be accessed by the derived class and objects, private members are still hidden, ensuring encapsulation and data protection.