Object-Oriented Programming (OOP) in C++

Introduction to OOP

• OOP is a programming paradigm based on the concept of "objects".
• Objects can contain data, in the form of fields (attributes) and code, in the form of procedures (methods).

Key Concepts in OOP

• Attributes and Methods
  • Attributes (Data members): Variables that hold data specific to a class or object.
  • Methods (Member functions): Functions that define the behavior of objects.

Basics of C++

• C++ is an object-oriented programming language that supports the creation and manipulation of objects.
• Classes and objects are fundamental to C++.

Classes and Objects

• Class: A blueprint for creating objects. Defines a datatype by bundling data and methods that work on the data.
• Object: An instance of a class.
  • Example: class Rect { int length; int width; void printArea(); };

Access Specifiers

• Public: Members are accessible from outside the class.
• Private: Members cannot be accessed from outside the class.
• Protected: Members are accessible within the class and by derived class.

Working with Classes in C++

• Declaration and Definition:
  • Declaration: class ClassName { //members };
  • Definition: This is where the methods' functionality is implemented.

Constructors and Destructors

• Constructor: A special method called when an object is created.
• Destructor: A special method called when an object is destroyed.

Inline Functions

• Defined inside a class and intended for small, frequently used functions to increase performance.

Getters and Setters

• Methods used to retrieve and update private data members.
• Example: int getLength() { return length; } void setLength(int myLength) { length = myLength; }

Struct vs Class

• Struct: Default access specifier is public.
• Class: Default access specifier is private.

Header and Source Files

• Header File (.h): Contains declarations of functions and variables.
• Source File (.cpp): Contains the implementation of functions.

Preprocessor Directives

• Used for file inclusion (#include), macro definitions (#define), and conditional compilations (#ifdef).

Example Programs

• Rational Numbers Program:
  • Demonstrates setting numerators and denominators, reducing fractions, and multiplying fractions.
  • Utilizes private data members and public methods for operations.

Encapsulation and Abstraction

• Encapsulation: Bundling data with methods that operate on the data.
• Abstraction: Hiding complex reality while exposing only the necessary parts.

Practical Components

• Linking and Compilation: Understanding how the compiler converts source code to machine code.
• Preprocessor: Instructs the compiler to process certain directives before actual compilation.

Important Notes

• Use of #ifdef and #endif to ensure header files are included only once.
• #pragma once is an alternative to #ifndef / #define / #endif mechanism for preventing multiple inclusions.

This lecture provides an overview of OOP concepts in C++ with examples and explains the role of classes, objects, and various access specifiers, as well as covering essential programming constructs like constructors, destructors, and inline functions.