Data Structures and Algorithms - ECE251 Tutorial 5

Data Structures and Algorithms - ECE251 Tutorial 5

• Object-Oriented Programming (OOP): A fundamental programming paradigm where programs are organized around objects rather than actions or logic.

• Classes and Objects:

  • A class is a blueprint for creating objects. It defines the attributes (data) and methods (functions) that objects of that class will have.
  • Objects are instances of a class. They are concrete entities that have specific values for the attributes defined in the class.

Object-Oriented Programming Terminology

• Attributes: Data members of a class, representing the properties of objects.

• Methods (or behaviors): Functions that define the actions an object can perform. These functions operate on the object's attributes.

Access Specifiers

• Public: Members accessible from outside the class.

• Private: Members accessible only within the class.

• Protected: Members accessible within the class and derived (subclass) classes.

Class Example (Rectangle)

• Private Members: double width; double length; These members are not directly accessible from outside the class.

• Public Members: void setWidth(double); void setLength (double); double getWidth() const; double getLength() const; double getArea() const; These members are accessible from outside the class.

Defining an Instance of a Class

• Objects are declared like structure variables (Rectangle r;).

• Members are accessed using the dot operator (.) Example: r.setWidth(5.2)

• Accessing private members using the dot operator will result in a compiler error.

Defining a Member Function

• Member functions are defined outside the class declaration but within the class's scope. The class name and scope resolution operator (::) are used. Example: int Rectangle::setWidth(double w) {width = w;}

Using const with Member Functions

• The const keyword after a function declaration (e.g., double getWidth() const;) indicates that the function will not modify any member variables in the object its called on. Useful for functions that only retrieve values, not modify them.

Program 13-1 (Example Code)

• Demonstrates a Rectangle class, including a constructor, getter methods (getWidth, getLength, getArea), and a setWidth function.

Avoiding Stale Data

• Data that is the result of calculations (like area in a rectangle) should be calculated directly within a method.

Constructors

• A constructor is a special method that is automatically called when an object is created.

• Its purpose is to initialize the attributes of the object.

• The constructor name is the same as the class name.

• It does not have a return type.

Passing Arguments to Constructors

• Constructors can be overloaded with different parameter lists.
• Provide constructors that take arguments when creating objects, allowing for initialization with specific values. Example Rectangle r(10, 5)

Overloading Constructors

• A class can have more than one constructor with different parameter lists. This allows for different ways to create objects of that class

Dynamically Allocating an Object

• Memory associated with an object can be dynamically allocated using new.
• The allocated memory must be released using delete when the object is no longer needed.

Destructors

• Destructors are automatically called when an object is destroyed.
• Their purpose is to clean up any allocated resources, such as dynamically allocated memory. -The destructor name is ~ClassName.

Arrays of Objects

• Objects can be stored in arrays.
• The default constructor is used if no explicit initialization list is provided.
• Use initialization lists for specific values when defining multi-argument constructors( e.g., InventoryItem inventory[3] = { "Hammer", "Wrench", "Pliers"}; )

Accessing Objects in an Array

• Use array indexing ([]) to access individual objects in an array.
• Access member functions of the object using the dot operator(.).

Inheritance

• Allows a class to inherit properties and methods from another class.

Encapsulation

• The mechanism for hiding the internal state of an object and requiring all interactions to be performed through methods.

Abstraction

• Hiding complex details and exposing only necessary features (e.g., using a TV remote).

Polymorphism

• Allows objects of different classes to be treated as objects of a common type. Allows methods with the same name to have different behaviors depending on the object they are called on.

Question (Employee Management)

• Design a program with object-oriented features.
• The program stores employee name, birth year, and years of experience.
• The user provides birth years, and the program calculates ages.

This quiz covers essential concepts in Object-Oriented Programming (OOP) as part of the ECE251 course. Students will explore classes, objects, attributes, methods, and access specifiers, enhancing their understanding of fundamental programming principles. Assess your knowledge of OOP terminology and practices.