Unit 5: Object-Oriented Programming (OOP) (10 Hours)

5.1 Programming Paradigms: Procedural, Structural, and Object-Oriented

Programming paradigms are different styles or approaches to programming that dictate how solutions are formulated.

Procedural Programming:
- Based on the concept of procedure calls.
- Emphasizes functions or procedures to operate on data.
- Example languages: C, Pascal.
- Advantages: Simplicity and ease of understanding; good for small programs.
Structural Programming:
- An extension of procedural programming.
- Focuses on improving the clarity and efficiency of code by using structures (such as control flow structures).
- Encourages breaking programs into smaller, manageable pieces.
- Example languages: C, Ada.
Object-Oriented Programming:
- Organizes software design around data (objects) rather than functions and logic.
- Promotes concepts such as encapsulation, inheritance, and polymorphism.
- Example languages: C++, Python.
- Advantages: Improved code reusability, scalability, and maintainability.

5.2 Features of OOP: Class, Object, Polymorphism, and Inheritance

OOP is characterized by several key features:

Class:

A blueprint for creating objects.
Encapsulates data for the object and methods to manipulate that data.

Example in C++:

cpp
class Car {
public:
    string color;
    string model;
    
    void displayInfo() {
        cout << "Model: " << model << ", Color: " << color << endl;
    }
};

Object:

An instance of a class.
Contains real values instead of variables.

Example:

cpp
Car myCar; // myCar is an object of class Car
myCar.color = "Red";
myCar.model = "Toyota";
myCar.displayInfo(); // Output: Model: Toyota, Color: Red

Polymorphism:

The ability to present the same interface for different data types.

Achieved through:

Method Overloading: Multiple functions with the same name but different parameters.

cpp
class Math {
public:
    int add(int a, int b) {
        return a + b;
    }
    double add(double a, double b) {
        return a + b;
    }
};

Method Overriding: A derived class provides a specific implementation of a method already defined in its base class.

cpp
class Animal {
public:
    virtual void sound() { cout << "Animal sound"; }
};

class Dog : public Animal {
public:
    void sound() override { cout << "Bark"; }
};

Inheritance:
- Mechanism by which one class (derived class) can inherit the attributes and methods of another class (base class).
- Types of inheritance:
  - Single Inheritance: One derived class inherits from one base class.
  - Multiple Inheritance: One derived class inherits from multiple base classes.
  - Multilevel Inheritance: A class is derived from another derived class.
  - Hierarchical Inheritance: Multiple classes are derived from the same base class.
- Example:
```
cpp
class Vehicle { // Base class
public:
    void start() { cout << "Starting vehicle"; }
};

class Car : public Vehicle { // Derived class
public:
    void honk() { cout << "Car honks"; }
};
```

5.3 Advantages of OOP

Modularity: Code is organized into discrete classes and objects, enhancing clarity and organization.
Reusability: Classes and objects can be reused across different programs, saving time and effort.
Maintainability: Easier to update and maintain code due to modular design.
Abstraction: Hides complex implementation details and exposes only the necessary features to the user.
Inheritance: Facilitates code reuse and extension through derived classes.

5.4 Applications of OOP

OOP is widely used across various domains due to its flexibility and effectiveness. Some applications include:

Software Development: Used in creating desktop applications, mobile apps, and web applications.
Game Development: Helps in modeling complex interactions between game objects.
Simulation and Modeling: Useful in scientific computing, simulations, and modeling real-world systems.
Database Management: Facilitates the design of object-oriented databases that model complex data relationships.