Classes, Member Functions & Access Specifiers (OOP)

Q1.

Analyze the given programs below, predict their outputs and determine whether they follow the principles of object-oriented programming correctly.

• I.

  #include <iostream>
  
  class Date
  {
  public:
      int m_day;
      int m_month;
      int m_year;
  };
  
  void printDate(Date date)
  {
      std::cout << date.m_day << '/' << date.m_month << '/' << date.m_year;
  }
  
  int main()
  {
      Date date{ 4, 10, 21 };
      printDate(date);
  
      return 0;
  }

• II.

  #include <iostream>
  
  class Date
  {
  public:
      int m_day;
      int m_month;
      int m_year;
  
      void printDate(Date date)
      {
          std::cout << date.m_day << '/' << date.m_month << '/' << date.m_year;
      }
  };
  
  int main()
  {
      Date date{ 4, 10, 21 };
      date.printDate(date);
  
      return 0;
  }

Q2.

What will be the output of the following programs?

• I.

  #include <iostream>
  
  class Message
  {
      std::string msg_str = "Welcome!";
  
  public:
      void greetUser()
      {
          std::cout << msg_str << '\n';
      }
  };
  
  int main()
  {
      Message.greetUser();
  
      return 0;
  }

• II.

  #include <iostream>
  
  class Coordinate
  {
  public:
      int x;
      int y;
  
      void printCoordinates()
      {
          std::cout << "(x, y): " << x << ", " << y << '\n';
      }
  }
  
  int main()
  {
      Coordinate coord = {4, 7};
      coord.printCoordinates();
  
      return 0;
  }

• III.

  #include <iostream>
  
  class Message
  {
  public:
      void greetUser()
      {
          std::cout << "Welcome!\n";
      }
  };
  
  int main()
  {
      Message message;
      message.greetUser();
  
      return 0;
  }

Q3.

A mobile shop wants to maintain information about different mobile phones.

Create a program that:

• Stores a phone’s brand, model, and price.
• Allows updating the price.
• Displays the phone’s details.

Phone Details:
Brand: Apple
Model: iPhone 16
Price: rs.85000

// After updating the price
Phone Details:
Brand: Apple
Model: iPhone 16
Price: rs.72500

Q4.

A library wants to keep track of the books available for readers.

Create a program that:

• Stores a book’s title, author, ISBN number (International Standard Book Number), and availability status.
• Allows borrowing and returning books.
• Displays the book’s details.

Book Details:  
Title: The Book of Mirdad  
Author: Mikhail Naimy
ISBN: 8743273565  
Status: Available  

// After borrowing the book  
Book Details:  
Title: The Book of Mirdad
Author: Mikhail Naimy
ISBN: 8743273565  
Status: Borrowed  

// After returning the book    
Book Details:  
Title: The Book of Mirdad
Author: Mikhail Naimy
ISBN: 8743273565  
Status: Available  

Q5.

What will be the output of the following programs?

• I.

  #include <iostream>
  
  class Date
  {
      int m_day;
      int m_month;
      int m_year;
  
      void printDate()
      {
          std::cout << m_day << '/' << m_month << '/' << m_year;
      }
  };
  
  
  int main()
  {
      Date date{ 4, 10, 21 };
      date.printDate();
  
      return 0;
  }

• II.

  #include <iostream>
  
  class Date
  {
      int m_day;
      int m_month;
      int m_year;
  
  public:
      void printDate()
      {
          std::cout << m_day << '/' << m_month << '/' << m_year;
      }
  };
  
  
  int main()
  {
      Date date;
  
      date.m_day = 11;
      date.m_month = 02;
      date.m_year = 2025;
  
      date.printDate();
  
      return 0;
  }

Q6.

Write a class named Point3d to represent a point in 3D cartesian coordinates.

• I.

  The class should contain:

  • Three private member variables of type int named m_x, m_y, and m_z;
  • A public member function named setValues() that allows you to set values for m_x, m_y, and m_z.
  • A public member function named print() that prints the point in the following format: (m_x, m_y, m_z).

  Make sure the following program executes correctly after writing your class:

  int main()
  {
      Point3d point;
      point.setValues(1, 2, 3);
  
      point.print();
      std::cout << '\n';
  
      return 0;
  }

  This should print:

  (1, 2, 3)

• II.

  • Add a function named isEqual() for checking if two points are equal or not, to your Point3d class. The following code should run correctly:

  int main()
  {
      Point3d point1;
      point1.setValues(1, 2, 3);
  
      Point3d point2;
      point2.setValues(1, 2, 3);
  
      std::cout << "point 1 and point 2 are" << (point1.isEqual(point2) ? "" : " not") << " equal\n";
  
      Point3d point3;
      point3.setValues(3, 4, 5);
  
      std::cout << "point 1 and point 3 are" << (point1.isEqual(point3) ? "" : " not") << " equal\n";
  
      return 0;
  }

  This should print:

  point 1 and point 2 are equal
  point 1 and point 3 are not equal