Computer Science Programming Basics in Ruby

10.7 Exercises

1. The class shown in Example 10-4 is used to keep track of the inventory for a company. It allows the user to assign a name and a manufacturer to each item. Write a class ItemNumber that inherits from Item that lets the user input a number of items owned for each item. Create an instance of the Item class and then an instance of the ItemNumber class.

   Example 10-4. Code for Exercise 1

        1 class Item
        2 	def initialize(item, maker)
        3 		@item = item
        4 		@maker = maker
        5 	end
        6 
        7 	def display
        8 		puts "Item ==> " + @item
        9 		puts "Maker ==> " + @maker
       10 	end
       11 end
   

2. Explain polymorphism.

3. Define OOP.

4. A university has three kinds of students: full-time students, part-time students, and off-campus students. Each student has the following information: name, address, phone number, Social Security number, student ID, and GPA. The full-time students should take at least 12 credits per semester. The part-time students should take less than 12 credits per semester. The off-campus students have no limit on credits per semester. The tuition fee for full-time students is $8,500 for up to 18 credits per semester and $600 for every credit over 18 credits. The tuition fee for part-time students is $750 per credit. The tuition fee for off-campus students is $520 per credit. Write a program that lists student information and calculates their tuition fees.

5. Write a program for the grocery store example described in Section 10.5.2, “Grocery Store.”