Lecture Notes: Introduction to OOPs

Overview

• Topic: Object-Oriented Programming (OOPs)
• Focus: Interview preparation, including placement and internship interviews, and college exams.
• Importance: Essential for tech interviews, programming understanding, and real-world implementation.

Objective

• Cover theory concepts and practical examples.
• Discuss important definitions for interviews.
• Code implementation of each concept in C++.
• Solve 30 MCQ questions at the end to reinforce understanding.

Key Concepts

Object-Oriented Programming

• Definition: A better way to write code, particularly for real-life scenarios.
• Implementation: Makes code easier to manage, especially at the organizational level.

Objects and Classes

• Object: An entity, e.g., pen, laptop, phone.
• Class: Blueprint for objects, determining appearance and properties.
  • Example: Toyota uses a blueprint to manufacture cars.

Practical Implementation in C++

• C++ STL (Standard Template Library) uses OOPs (e.g., vector, string, stack libraries).
• Key Terms:
  • Class: Blueprint or group of objects.
  • Object: Instance of a class, with properties and methods.

Properties and Methods

• Properties: Attributes or values associated with an entity.
  • Example: Teacher's name, department, subject, salary.
• Methods: Functions written inside a class, also known as member functions.

Access Modifiers

• Private: Accessible only within the class.
• Public: Accessible from outside the class.
• Protected: Accessible in the class and its derived classes.
  • Important for inheritance.

Encapsulation

• Definition: Wrapping up of data and member functions in a single unit (class).
• Purpose: Implements data hiding, protecting sensitive information using access modifiers.

Constructors and Destructors

Constructors

• Special method called automatically when an object is created.
• Types:
  • Non-Parameterized Constructor
  • Parameterized Constructor
  • Copy Constructor
• Purpose: Initialize data members.

Destructors

• Opposite of constructors, called when an object is destroyed.
• Purpose: Deallocation of memory, especially important for dynamically allocated memory.

Inheritance

• Definition: Deriving properties and methods from another class.
• Purpose: Promotes code reusability.
• Types:
  • Single Inheritance
  • Multi-level Inheritance
  • Multiple Inheritance
  • Hierarchical Inheritance
  • Hybrid Inheritance
• Modes: Public, Protected, Private

Polymorphism

• Definition: Ability to take multiple forms.
• Types:
  • Compile-time Polymorphism (Static):
    • Function Overloading
    • Constructor Overloading
  • Run-time Polymorphism (Dynamic):
    • Function Overriding
    • Virtual Functions

Abstraction

• Definition: Hiding unnecessary details and showing only the important parts.
• Implementation: Access Specifiers and Abstract Classes
• Purpose: Simplifies complex systems.

Static Keyword

• Used to maintain a single version of a variable across all objects.
• Usage:
  • Static variables
  • Static objects

Additional Concepts

• Virtual Functions: Dynamic behavior based on pointer/reference type.
• Friend Functions and Classes: Advanced topics for further study.

Conclusion

• Importance of understanding OOPs for interviews and real-world programming.
• Practice solving MCQs and creating notes for better preparation.

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Next Steps: Solve the provided MCQs to reinforce learning and prepare for interviews effectively.