Object-Oriented Programming Concepts

Programming Paradigms

• Three main paradigms are Procedural, Functional, and Object-Oriented Programming (OOP)
• Procedural Programming executes statements sequentially, using procedures (functions, modules, subroutines, or methods) as logical units. Basic constructs are blocks of code called procedures.
• Functional Programming emphasizes declarations and expressions, avoiding flow control statements like for, while, break, continue, and goto. Functions are the basic units, treated like variables.
• OOP builds programs around objects representing real-world entities, extending procedural programming. Classes are blueprints for objects, and objects are specific instances of those classes. OOP makes programming more flexible, user-friendly, and less complex.

Procedural vs. Object-Oriented Programming (OOP)

• Procedural programming emphasizes procedures (or functions) over data.
• OOP emphasizes data over procedures.
• Procedural programming is a top-down approach; OOP is a bottom-up approach.
• Procedural programming doesn't model real-world entities; OOP does.
• Procedural programs are decomposed into functions or procedures; OOP programs are decomposed into objects.

OOP Concepts

• Class: A blueprint or template defining the characteristics (attributes) and behaviors (methods) of objects. It's a user-defined data type that contains attributes and operations.
• Object: A specific instance of a class, possessing the attributes and behaviors defined by its class.
• Attribute: Data member; it details the characteristics that define an object. Represents the properties of the object.
• Method: A self-contained block of code that performs actions. Comparable to procedures in procedural programming, its implementation is within the body of the method.

Data Abstraction and Encapsulation

• Data Abstraction: Showcasing only essential details of an entity while hiding internal complexities. Hides unnecessary details
• Data Encapsulation: Combines data fields (attributes) and methods (activities) into a single unit (class). It protects the data by only allowing access via methods. This concept is called encapsulation.

Classes and Objects

• Classes define the structure and behavior of objects.
• Objects are instances of classes, having specific data values and behaviors.

Methods

• Methods are program modules containing code that performs a specific task. They are reusable statements that execute automatically when a programmer calls (invokes) them. Methods group logical units of the program. Methods can be called unlimited number of times.
• Method Header: includes access modifiers, static, return type, method name, and parameters.
• Method Body: contains the code to perform the task of the method, using statements.
• Main method: A special method that automatically executes when a program starts.
• Access Modifiers: Keywords defining access levels (e.g., public, private, protected).

Inheritance

• Mechanism enabling classes to inherit properties (data fields) and behaviors (methods) from other classes (parent or base class).
• The class that inherits is called a derived class, child class, or subclass; it inherits properties from the base class.

Polymorphism

• Feature allowing the same method name to have different behaviors in different classes (or objects).
• Allows the same method to act in different contexts based on the object type.

Operator Overloading and Function Overloading

• Operator Overloading: Giving different meanings to operators depending on the usage context (different types of operands).
• Function Overloading: Creating multiple methods with the same name but different parameters.

Constructors

• Special methods that initialize objects when they are created.
• The constructor's name is the same as the class name.

Data Fields

• Data members, variables declared within a class to store data belonging to an object.