Example 3 -
Create a class called card that maintains a library card catalog entry. Have the class store a book's title, author, and number of copies on hand. Store the title and author as strings and the number on hand as an integer. Use a public member function called store() to store a book's information and a public member function called show() to display the information. Include a short main() function to demonstrate the class.

(a) The question clearly indicates that we need a class. This is not always the case. You can tell if a class will be convenient if you need to store several properties that are connected somehow. This question has the properties of a book title, author and number of copies on hand. Since they are all related to the books in a library, that can be grouped in a class with those three properties (variables).

Since the class should control access to these variables, we will make them private. Then we need to make member functions that access and/or modify the variables. The member functions should be public so that we can use them outside of the class (when we create an instance of the object).

Fortunately, this question lays out exactly what is needed. We will have 2 member functions. store() will save the library card catalog entry information and show() will print the information to the screen.

(b) Next, we will need a main() function. This is also called a driver program.

A driver simply instantiates the class and uses all the member variables and member functions. In this way, the entire class is tested and demonstrated. Once you know your class is functioning properly, you can re-use it for any other program you are creating. (One of the benefits to the object-oriented paradigm).

Designing the class:

We need 3 member variables:
(1) string book_title
(2) string author_name
(3) integer copies_on_hand
We need 2 member functions:
(1) store() - this will set the three member variables
(2) show() - this will display the values for the three member variables to the screen
Design Decision:
It hasn't been requested directly by the question, but we're going to create 2 versions of the store() function (Function Overloading).
(1) store() - the parameterless version will prompt the user for the information
(2) store(string, string, integer) - the version with parameters will be available in the event that the information is known and can be hard-coded into the program.
Sometimes it is useful to overload a function in this manner so that it can be used in different ways. This can make your class more user-friendly.

This class happens to be quite simple. Rather than show the pseudocode, I leave this to you as an exercise. Try it before you look at the source code files.
View the class definition (catalogCard.h)
View the function definitions (catalogCard.cpp)

The main() function is just a small program that instantiates the class and tries each member function to show that it works.
Again, I leave the pseudocode to you as an exercise.
View the driver program (example3.cpp)

Note: To compile this code, type the following at the hercules prompt:
CC -LANG:std example3.cpp catalogCard.cpp