Name:
Sec: 11/01/2005
Lab 4.1 Defining and Using Classes
Recall that two structured data types are arrays, which have
elements of the same type, and structures, which have elements of
differing types. Another structured data type is a class, which is
specifically designed to combine data and functions in a single unit. A
class is a collection of a fixed number of components. The
components of a class are called the members of the class. If a
member of a class is a variable, you define it just like any other
variable, but you cannot initialize it at definition. If a member of a
class is a function, you typically use the function prototype to define
that member. Member functions can directly access any data
member of the class without passing that data member as an
argument.
No memory is allocated in a class definition. Instead, memory is
allocated when the class is instantiated (an object is created).
Additionally, the semicolon (;) is part of the syntax. The members of a
class are classified into three categories: private, public, and
protected. By default, all members of a class are private. Private
members cannot be accessed outside of the class. A public member
is accessible outside the class. Protected members will be discussed
in Chapter 13.
A class and its members can be described graphically using Unified
Modeling Language (UML) notation. A UML diagram contains three
boxes stacked vertically. The top box contains the name of the class;
the middle box contains the data members and their data types; and
the bottom box contains the member method names, parameter list,
and return types. The + (plus) sign indicates that it is a public
member; the - (minus) sign indicates that it is a private member. The
# (pound) symbol indicates that it is a protected member.
Objectives
In this lab, you define a class and declare objects.
After completing this lab, you will be able to:
Use basic UML notation to design and specify a class.
Write a driver program that contains a class definition.
Instantiate an object of a class.
Practice using coding projects and working with a program
defined across multiple files.
Describing Classes Using the Unified Modeling Language (UML)
