Chapter 14: Problem 49

True or False An entire class may be declared a friend of another class.

Short Answer

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Answer: True

Step by step solution

Consider Friend Classes

In C++, a class can declare another class to be its friend. A friend class has access to all the private and protected members of the declarer class. This means that the friend class can directly access variables and methods that would otherwise be inaccessible. It's important to note that the friendship is not mutual; the class that declared the other class as its friend doesn't automatically have access to the private and protected members of the friend class. Here is an example: ```cpp class ClassA { friend class ClassB; // ... rest of ClassA's declaration }; class ClassB { // ClassB can access ClassA's private and protected members // ... rest of ClassB's declaration }; ```

Friend Class Declaration Answer

Based on the definition and example above, an entire class may indeed be declared a friend of another class. Therefore, the statement is True.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

C++ classes

In the world of C++, classes are foundational to object-oriented programming, serving as blueprints for creating objects. Classes encapsulate data for the objects, combining state (variables) and behavior (functions or methods) into a single neat package.

For instance, consider a simple class that represents a book:

Access specifiers in C++

Access specifiers in C++ determine how the members of a class can be accessed. There are three primary access specifiers: public, private, and protected.

Public members can be accessed from anywhere in the program where the object is visible.
Private members can only be accessed by other members of the same class (or friends, as we will discuss in the 'C++ friend keyword' section).
Protected members are like private members but can also be accessed in derived classes (subclasses).

The use of access specifiers is necessary for the encapsulation property of object-oriented programming, as it allows a class to hide its internal state and restrict access to prevent unintended manipulation.

Here's a simple class to illustrate the use of access specifiers:

C++ friend keyword

The friend keyword in C++ plays an exceptional role in accessing private and protected members of classes. When a class is declared as a friend, it can access the private and protected members of the class that provided the friendship.

This feature is potent as it allows for intimate relationships between classes, but it must be used judiciously to prevent exposing sensitive data. Friendship is not transitive (if class A is a friend of B, and B is a friend of C, A is not automatically a friend of C) and not symmetric (if class A is a friend of B, B is not automatically a friend of A).

Here is an example to clarify the concept of friendship in C++:

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True or False An entire class may be declared a friend of another class.

Short Answer

Step by step solution

Consider Friend Classes

Friend Class Declaration Answer

Key Concepts

C++ classes

Access specifiers in C++

C++ friend keyword

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