OOPs Concepts - From Zero to Advanced

Introduction

• Importance of mastering OOPs for interviews and programming.
• Focus on theory, definitions, examples, and code in C++.

Object-Oriented Programming (OOP)

• A better way to write code by using real-world scenarios.
• Examples include libraries like STL in C++.

Basic Concepts

Classes and Objects

• Object: Real-world entities (e.g., pen, laptop).
• Class: Blueprint for creating objects (e.g., Toyota blueprint for cars).
• Example: Teacher system in a college.

Access Modifiers

• Private: Accessible only within the class.
• Public: Accessible from outside the class.
• Protected: Accessible in derived classes (important for inheritance).

Encapsulation

• Wrapping data and functions into a single unit (a class).
• Supports data hiding by using private access modifiers.

Constructors

• Purpose: Initialize objects.
• Types: Non-parameterized, parameterized, copy constructor.
• Copy Constructor: Copies properties from one object to another.
• Shallow vs. Deep Copy: Issue with dynamic memory allocation in shallow copy.

Destructor

• Opposite of constructor; used to deallocate memory.
• Important for managing dynamically allocated memory with delete keyword.

Inheritance

• Purpose: For code reusability.
• Types:
  • Single Inheritance
  • Multi-level Inheritance
  • Multiple Inheritance
  • Hierarchical Inheritance
  • Hybrid Inheritance

Polymorphism

• Meaning: Ability of objects to take on many forms.
• Types:
  • Compile-time Polymorphism: Function and constructor overloading.
  • Runtime Polymorphism: Function overriding and virtual functions.

Abstraction

• Hiding unnecessary details and showing only necessary parts.
• Implemented using access modifiers and abstract classes.

Abstract Classes

• Used as a blueprint for other classes.
• Contains pure virtual functions.

Static Keyword

• Used to define variables or functions that persist throughout the program.
• Static Variable: Shared among all instances of a class.
• Static Object: Persists for the lifetime of the program.

Further Reading

• Friend Functions and Friend Classes (for deeper understanding).

Conclusion

• Understanding OOPs concepts is crucial for interview success.
• Encourage solving MCQs and making detailed notes for better retention.