Quiz 2 review

Objective

Review the course topics and content that will be assessed on the second quiz.

Quiz Details

• Paper quiz
• 4 multi-part questions, you will be asked to review code and answer questions about the code, write code, or draw something like a UML diagram.
• Total of 50 points
• 30 minutes to complete the quiz

What to Study

Text book: Programming Principles and Practice Using C++, 2nd Edition by Bjarne Stroustrup

• Chapter 9 Classes, etc.

Lectures:

• Slides: Classes and OOP
  • Classes
    • Class syntax
    • access specifiers (public, private, and protected)
  • Abstraction
  • Encapsulation
• Slides: Enum, Static, Overloading
  • Constructors
  • Enumerations
  • Static members
  • Operator overloading
• Lecture Notes: Scope, Friends, Destructors, Composition, and UML
  • Scope
  • Friends
  • Destructors
  • Composition
  • UML Diagrams
• Slides: Inheritance, Polymorphism, Virtual Functions, Abstract Classes
  • Inheritance
  • Polymorphism
  • Virtual functions

Practice Questions

Access Specifiers (public, private, protected)

Book.cpp

class Book {
public:
    Book(std::string t) : title(t) {}

    std::string getTitle() const {
        return title;
    }

    void summarize() {
        std::cout << "This is a book titled: " << title << std::endl;
    }

protected:
    std::string title;
};

class Novel : public Book {
public:
    Novel(std::string t, std::string g) : Book(t), genre(g) {}

    void summarize() {
        std::cout << "This is a " << genre << " novel titled: " << title << std::endl;
    }

private:
    std::string genre;
};

int main()
{
    Novel mystery{"A Study in Scarlet", "Mystery"};

    // Can you do this?
    std::cout << mystery.title << std::endl; 

    return 0;
}

Consider the C++ program Book.cpp above.

• Describe the purpose of the protected access specifier in the Book class, and explain how it contrasts with the private access specifier.
• In the Novel class, which inherits from Book, can the summarize method directly access the title attribute? Provide a justification for your answer.
• If you create an object (instance) of the Novel class within the main function, can you directly access the title attribute from that object? Elaborate on your answer.

Dynamic Memory Allocation and Deallocation

Particle.cpp

class Particle {
public:
    Particle(float x, float y) : posX(x), posY(y) {}

    void move(float dx, float dy) {
        posX += dx;
        posY += dy;
    }

    void printPosition() const {
        std::cout << "Position: (" << posX << ", " << posY << ")" << std::endl;
    }

private:
    float posX, posY;
};

int main() {
    Particle* p1 = new Particle(5.0, 7.5);
    p1->move(2.0, -3.0);
    p1->printPosition();

    // Some code here...

    return 0;
}

Consider the C++ program Particle.cpp above.

• What does the new keyword do in the main function?
• What is returned from the expression new Particle(5.0, 7.5)?
• As the code stands, there’s a potential issue related to dynamic memory management. Identify the issue and explain why it’s problematic.
• Provide a modification to the code to fix the potential memory management issue you identified.

Polymorphism and Virtual Functions

Media.cpp

class MultimediaContent {
public:
    virtual void play() {
        std::cout << "Playing generic multimedia content." << std::endl;
    }
};

class Song : public MultimediaContent {
public:
    void play() {
        std::cout << "Playing a melodious song." << std::endl;
    }
};

class Video : public MultimediaContent {
public:
    void play() {
        std::cout << "Streaming a captivating video." << std::endl;
    }
};

int main() {
    MultimediaContent* content1 = new Song();
    MultimediaContent* content2 = new Video();

    content1->play();  // ?
    content2->play();  // ?

    delete content1;
    delete content2;
    
    return 0;
}

Consider the C++ program Media.cpp above.

• What is the significance of the virtual keyword in the MultimediaContent class regarding the play method?
• Given the main function provided, what will the output be when the program is executed?
• Describe what is meant by the term polymorphism in the context of the provided code.

Implementing the constructor and methods of a class

Consider the following C++ code in the file Calculator.h.

#ifndef CALCULATOR_H
#define CALCULATOR_H

class Calculator {
public:
    // Constructor: Initializes the calculator with a given value.
    Calculator(double initialValue);

    // Adds a value to the current result.
    void add(double value);

    // Subtracts a value from the current result.
    void subtract(double value);

    // Multiplies the current result by a given value.
    void multiply(double value);

    // Divides the current result by a given value. If the given value is zero, do nothing.
    void divide(double value);

    // Returns the current result.
    double getResult() const;

private:
    double result;
};

#endif

Use the C++ code above to answer the following questions.

• Write the C++ code that you would put into the file Calculator.cpp to implement the constructor and methods for the Calculator class found in Calculator.h. Do your best to write code that will compile. Remember to use #include as needed for external libraries or the Calculator.h file.

• Draw a UML diagram that represents the Calculator class. Remember to include the name of the class, the member variables (attributes) and their type, and member functions (methods) and their return and parameter types. You should include the access specifiers for each attribute and method. If an attribute or method is public indicate this with a + sign. If an attribute or method is private indicate this with a - sign.