C# OOP (Object-Oriented Programming) Tutorial Notes

This document summarizes the key topics in C# OOP that you should study and practice.
It follows the sequence of tutorials for better understanding.

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📑 Table of Contents

1. Introduction, Classes and Objects
2. Constructors in Programming
3. Events and Event Handlers
4. Encapsulation Explained
5. Inheritance Explained
6. Polymorphism
7. Partial Classes
8. Interfaces
9. Override Keyword & Overriding Methods
10. Static Properties and Static Methods
11. How to Study
12. Recommended Practice

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1. Introduction, Classes and Objects

• What is Object-Oriented Programming (OOP)?
• Difference between Class (blueprint) and Object (instance).
• How to define a class in C#.
• Creating and using objects.

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2. Constructors in Programming

• Purpose of constructors.
• Types of constructors:
  • Default constructor
  • Parameterized constructor
  • Copy constructor
• Constructor overloading.

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3. Events and Event Handlers

• What are events in C#.
• Delegates and how they connect to events.
• Defining and subscribing to events.
• Event-driven programming examples.

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4. Encapsulation Explained

• Concept of data hiding.
• Using private fields with public properties.
• get and set accessors.
• Benefits of encapsulation in real-world applications.

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5. Inheritance Explained

• What is inheritance and why it is used.
• Base (parent) and derived (child) classes.
• : base keyword in C#.
• Benefits of code reuse.

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6. Polymorphism

• Concept of “many forms.”
• Compile-time polymorphism (method overloading).
• Run-time polymorphism (method overriding with virtual and override).
• Example: Shapes (Circle, Rectangle) implementing different behaviors.

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7. Partial Classes

• Splitting one class across multiple files.
• Benefits: teamwork and maintainability.
• Example usage in auto-generated code.

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8. Interfaces

• What are interfaces and why we use them.
• Defining and implementing interfaces.
• Difference between abstract classes and interfaces.
• Real-world examples (e.g., IDisposable, IEnumerable).

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9. Override Keyword & Overriding Methods

• Difference between method overloading and overriding.
• Using virtual, override, and sealed.
• Rules of method overriding in C#.

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10. Static Properties and Static Methods

• What does static mean in C#.
• Static fields and methods shared across all objects.
• When to use static vs instance members.
• Example: Utility classes like Math.

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✅ How to Study

1. Start with Classes and Objects as the foundation.
2. Move to Constructors → Encapsulation → Inheritance.
3. Learn Polymorphism for flexible code.
4. Explore Events and Interfaces for real-world applications.
5. Finish with advanced concepts like Partial Classes and Static Members.

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🚀 Recommended Practice

• Build a simple Bank Account System:
  • Encapsulation: Balance field with getter/setter.
  • Constructors: Initialize account details.
  • Inheritance: SavingsAccount, CheckingAccount.
  • Polymorphism: Different Withdraw implementations.
  • Interface: ITransaction for Deposit/Withdraw.
  • Events: Trigger event when balance is low.

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