Object Oriented Programming Lecture Notes

Introduction

• Today's topic: Object Oriented Programming (OOP)
• Importance of OOP in C++ at the industrial level
• Fundamental OOP topics relevant for interviews and placements

Agenda

1. Why OOP?
2. What is OOP?
3. Fundamentals of OOP:
   • Class
   • Object
   • Constructor
   • Destructor
   • Encapsulation
   • Abstraction
   • Inheritance
   • Access Specifiers
   • Polymorphism
4. Code implementation alongside theoretical explanations

Why Object Oriented Programming?

• Transition from Procedure Oriented Programming (POP)
• POP: Conventional programming paradigm using high-level languages (e.g., C, COBOL, FORTRAN)
  • Programs divided into tasks grouped into functions
  • Heavy reliance on global data
  • Problems with global data:
    • Difficult to track changes
    • Changes in data structure require extensive updates
• OOP focuses on binding data with functions using objects, improving data protection and accessibility.

What is OOP?

• OOP is a programming paradigm based on objects that have data and methods associated with them.
• Objects can only be accessed through their respective functions, enhancing data security.

Key Concepts in OOP

Class

• User-defined data type that provides a blueprint for creating objects.
• Example: Defining a Fruit class with properties (e.g., color, taste).

Object

• Instance of a class; variables of a class type.
• Example: Creating objects like mango, apple, grapes from the Fruit class.

Constructor

• Special function called when an object is created to initialize its properties.
• Types of constructors:
  • Default Constructor: No parameters, initializes with default values.
  • Parameterized Constructor: Accepts parameters to initialize properties.
  • Copy Constructor: Initializes an object using another existing object.

Destructor

• Function called when an object is deleted, cleans up resources.
• Defined using the tilde operator (~) followed by the class name.

Encapsulation

• Bundling of data (attributes) and methods (functions) into a single unit (class).
• Restricts direct access to some object components, which can be achieved using access specifiers.

Abstraction

• Hiding unnecessary details from the user and showing only essential features.
• Example: Using a function without needing to understand its internal workings.

Inheritance

• Mechanism where a new class derives properties and behaviors (methods) from an existing class.
• Types of inheritance:
  • Single Inheritance: One class inherits from another.
  • Multi-level Inheritance: A class inherits from a derived class.
  • Multiple Inheritance: A class inherits from multiple parent classes.
  • Hierarchical Inheritance: Multiple classes inherit from a single parent class.
  • Hybrid Inheritance: Combination of multiple inheritance types.

Access Specifiers

• Define how members of a class can be accessed:
  • Public: Accessible from anywhere.
  • Protected: Accessible in the class itself and derived classes.
  • Private: Accessible only within the class.

Polymorphism

• Ability for different classes to be treated as instances of the same class through inheritance.
• Types of polymorphism:
  • Compile-time Polymorphism: Resolved during compilation (e.g., function overloading, operator overloading).
  • Runtime Polymorphism: Resolved during program execution (e.g., function overriding with virtual functions).

Friend Function

• A non-member function that can access private members of a class.
• Declared using the friend keyword within the class definition.

Conclusion

• Comprehensive coverage of fundamental OOP concepts in C++ for future applications in data structures and algorithms.
• Next lecture will build on these concepts using linked lists.
• Recommended: Review the video, practice coding examples, and implement function/operator overloading.