1. Exercises on Basic OOP TCP1201: 2013/2014

2. Catch the Bug 1 class Point { private : int x, y; public : Point(int u, int v) : x(u), y(v) { } int getX() { return x; int getY() { return y; } }; int main() { Point p(5, 3); cout << p.x << " " << p.y << "\n"; return 0; } BUGS: x and y are private members and cannot be accessed outside of the class.

3. Catch the Bug 2 class Point { private : int x, y; public : Point (int u, int v) : x(u), y(v) { } int getX () { return x; } int getY () { return y; } void setX (int newX ) const { x = newX ; } }; int main () { Point p(5, 3); p. setX (9001) ; cout << p. getX () << ’ ’ << p. getY (); return 0; } BUGS: The function setX is declared const,

4. Catch the Bug 3 class Point { private : int x, y; public : Point (int u, int v) : x(u), y(v) { } int getX () { return x; } void setX(int newX); }; void setX (int newX) { x = newX; } int main() { Point p(5, 3); p.setX(0); cout << p.getX() << " " << "\n"; } BUGS: setX is missing the scope; the function should be declared as: void Point::setX(int newX) { x = newX; }

5. Catch the Bug 4... int size; cin >> size; int *nums = new int[size]; for(int i = 0; i < size; ++i) { cin >> nums[i]; }... // Calculations with nums omitted delete nums;... BUGS: Deleting a dynamically allocated array requires delete[ ], not delete.

6. Catch the Bug 5 class Point { private : int x, y; public : Point (int u, int v) : x(u), y(v) { } int getX () { return x; } int getY () { return y; } }; int main () { Point *p = new Point (5, 3); cout << p  getX () << ’ ’ << p  getY (); return 0; } 14 BUGS: p is allocated using new, but is never deallocated with delete. Every piece of memory allocated with new must be deallocated somewhere with a corresponding delete. delete p;

7. Catch the Bug 6 int add(int x, int y) { return x + y; } int main(){ int a = 1, b = 2; cout << add(a,b) << endl; double d = 1.8, e = 1.3; cout << add(d, e) << endl; } Solution: Function add does not adds two double numbers. Use a template function to allow the function add to accept any data type. template T add(T x, T y) { return x + y; }

8. Catch the Bug 7 class Rectangle { protected: int width; int height; public: void setWidth(int w) { width = w; } void setHeight(int h) { height = h; } int getArea() { return (width * height); } }; int main(void) { Rectangle Rect; Rect.setWidth(5); Rect.setHeight(7); Rect.getArea(); } Solution: Rect.getArea() returns an integer only. It does not print out the value. To print out the value, you should use cout as follows: cout << "Total area: " << Rect.getArea() << endl;

9. Catch the Bug 8 class Rectangle { protected: int width; int height; public: void setWidth(int w) { width = w; } void setHeight(int h) { height = h; } int getArea() { return (width * height); } }; int main(void) { Rectangle* Rect = new Rect; Rect.setWidth(5); Rect.setHeight(7); cout << "Total area: " << Rect.getArea() << endl; delete Rect; } Solution: Rect  setWidth(5); Rect  setHeight(7); cout << "Total area: " << Rect  getArea() << endl;

10. Catch the Bug 9 class Shape { protected: int width; int height; public: void setWidth(int w) { width = w; } void setHeight(int h) { height = h; } }; class Rectangle: Shape { public: int getArea() { return (width * height); } }; int main(void) { Rectangle Rect; Rect.setWidth(5); Rect.setHeight(7); Rect.getArea(); } Solution: Shape is not recognized. The definition of Rectangle class should be: class Rectangle: public Shape

11. Programming Exercise 1 (Class Template) The following program show the usage of function template to compute the addition of two numbers. Extend the program below to use class template to develop a simplified calculator with the functions of adding, substracting, multiplying and dividing two numbers. template T add(T x, T y) { return x + y; } int main(){ int a = 1, b = 2; cout << add(a,b) << endl; double d = 1.8, e = 1.3; cout << add(d, e) << endl; }

12. Solution: template class Calculator { public: T add(T a, T b); T subtract(T a, T b); T multiply(T a, T b); double divide(T a, T b); }; template T Calculator ::add(T a, T b) { return a + b; } template T Calculator ::subtract(T a, T b) { return a - b; } Programming Exercise 1 (Class Template)

13. template T Calculator ::multiply(T a, T b) { return a * b; } template double Calculator ::divide(T a, T b) { return (double) a / b; } int main() { Calculator iCalc; cout << iCalc.add(1, 2) << endl; cout << iCalc.subtract(1, 2) << endl; cout << iCalc.multiply(1, 2) << endl; cout << iCalc.divide(1, 2) << endl; Calculator fCalc; cout << fCalc.add(1.7, 2.2) << endl; cout << fCalc.subtract(1.7, 2.2) << endl; cout << fCalc.multiply(1.7, 2.2) << endl; cout << fCalc.divide(1.7, 2.2) << endl; }

14. Programming Exercise 2 (OOP Basics) Define a class named GroceryItem. Include private fields that hold an item’s stock number, price, quantity in stock, and total value. Write a public function named dataEntry that calls four private functions. Three of the private functions prompt the user for keyboard input for a value for one of the data fields stock number, price, and quantity in stock. The function that sets the stock number requires the user to enter a value between 1000 and 9999 inclusive; continue to prompt the user until a valid stock number is entered. The functions that set the price and quantity in stock require non- negative values; continue to prompt the user until valid values are entered. Include a fourth private function that calculates the GroceryItem ’s total value field (price times quantity in stock). Write a public function that displays a GroceryItem ’s values. Write a driver program that declares an array of 10 GroceryItem objects. Assign values to all 10 items and display them.

15. Programming Exercise 3 (OOP Basics) Define a class named CoffeeOrder. Declare a private static field that holds the price of a cup of coffee as $1.25. Include private integer fields that you set to a flag value of 1 or 0 to indicate whether the order should have any of the following: cream, milk, sugar, or artificial sweetener. Include a public function that takes a user’s order from the key board and sets the values of the four fields in response to four prompts. If the user indicates both milk and cream, turn off the milk flag to allow only cream. If the user indicates both sugar and artificial sweetener, turn off the artificial sweetener flag, allowing only sugar. Include another function that displays the user’s completed order. Write a driver program to test the functions of the class.

16. Programming Exercise 3a (OOP Basics) Define a class named CoffeeOrder. Declare a private static field that holds the price of a cup of coffee as $1.25. Include private integer fields that you set to a flag value of 1 or 0 to indicate whether the order should have any of the following: cream, milk, sugar, or artificial sweetener. Include a public function that takes a user’s order from the key board and sets the values of the four fields in response to four prompts. If the user indicates both milk and cream, turn off the milk flag to allow only cream. If the user indicates both sugar and artificial sweetener, turn off the artificial sweetener flag, allowing only sugar. Include another function that displays the user’s completed order. Write a driver program to test the functions of the class.

17. Programming Exercise 3b (OOP Basics) Using the CoffeeOrder class, write a driver program that continues to ask a user for an order in a loop until the user indicates the order is complete or 10 orders have been placed, whichever comes first. After the user indicates that ordering is complete, display a recap of all the coffee orders, including the cream, milk, sugar, and sweetener status of each, as well as a count of the number of coffees ordered and the total price.

18. Programming Exercise 5 (Inheritance) Create a base class named Book. Data fields include title and author; functions include those that can set and display the fields. Derive two classes from the Book class: Fiction, which also contains a numeric grade reading level, and NonFiction, which contains a variable to hold the number of pages. The functions that set and display data field values for the subclasses should call the appropriate parent class functions to set and display the common fields, and include specific code pertaining to the new subclass fields. Write a driver program that demonstrates the use of the classes and their functions.

19. Programming Exercise 6 (Inheritance) Implement a base class Account and derived classes Savings and Checking. In the base class, supply member functions deposit and withdraw. Provide a function daily_interest that computes and adds the daily interest. For calculations, assume that every month has 30 days. Checking accounts yield interest of 3 percent monthly on balances over $1000. Savings accounts yield interest of 6 percent on the entire balance. Write a driver program that makes a month’s worth of deposits and withdrawals and calculates the interest every day.