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OOPS: Abstraction & Encapsulation

1. Why Did We Move Beyond Procedural Programming?

1.1 Early Languages

1. Machine Language (Binary)

  • Direct CPU instructions in 0s & 1s
  • Drawbacks:
  • Very error-prone
  • Hard to write and maintain
  • No abstraction

2. Assembly Language

  • Uses mnemonics (e.g., MOV A, 61h)
  • Still hardware-dependent
  • Not scalable for large systems

1.2 Procedural Programming

Features: - Functions
- Control structures (if, loops)
- Code blocks

Advantages: - Better readability than assembly
- Modular for small programs

Limitations: - Poor real-world modeling
- No proper data security
- Limited scalability and reuse

2. Object-Oriented Programming (OOP)

Idea: Model programs using real-world entities as objects

Benefits: - Maps well to real-world systems
- Better data security
- Code reuse (inheritance, interfaces)
- Scalable and modular

3. Basic Concepts

  • Object: Real-world entity with data + behavior
  • Class: Blueprint of object
  • Instance: Actual object created from class

4. Abstraction

Definition:
Hides implementation details and exposes only essential functionality

Examples

Car

  • You use: start, accelerate, brake
  • You don’t see: engine internals

TV / Laptop

  • You press buttons
  • You don’t see internal processing

In Programming

  • Using if, for, while instead of machine-level instructions
  • Compiler handles low-level details

Code Example (Abstract Class)

```cpp class Car { public: virtual void startEngine() = 0; virtual void shiftGear(int newGear) = 0; virtual void accelerate() = 0; virtual void brake() = 0; virtual ~Car() {} };