Abstract Classes & Interfaces

1What are Abstract Classes?✨

Abstract classes are classes that cannot be instantiated on their own. They are designed to be base classes that other classes can inherit from. An abstract class typically contains at least one pure virtual function.

2Why Use Abstract Classes?🎯

• ✓ Provides a common interface for derived classes
• ✓ Encourages code reuse and organization
• ✓ Allows for defining a blueprint for derived classes
• ✓ Ensures derived classes implement specific methods

3Defining an Abstract Class💡

To define an abstract class in C++, declare a virtual function with = 0 at the end of its declaration. Here's an example:

class Shape {
public:
    virtual void draw() = 0; // Pure virtual function
};

4Creating Derived Classes🚀

When you create a class that inherits from an abstract class, you must implement all pure virtual functions. Here’s how it looks:

class Circle : public Shape {
public:
    void draw() override {
        cout << "Drawing a Circle" << endl;
    }
};

5Using Interfaces🔍

An interface in C++ can be created using an abstract class that has only pure virtual functions. This defines a contract for derived classes without any implementation.

class Drawable {
public:
    virtual void draw() = 0; 
    virtual void resize(int width, int height) = 0;
};

6Implementing Interfaces⭐

Any class inheriting from an interface must implement all its methods. For example:

class Square : public Drawable {
public:
    void draw() override {
        cout << "Drawing a Square" << endl;
    }

    void resize(int width, int height) override {
        cout << "Resizing Square to " << width << "x" << height << endl;
    }
};

7Practical Application🧩

Abstract classes and interfaces are widely used in software design. They allow you to create flexible and maintainable code. You can design a graphics application where different shapes can be drawn and resized using a common interface.

8This Grade's Project🎈

• ✓ Create a graphics application with various shapes
• ✓ Implement abstract classes for different shape types
• ✓ Use interfaces for shape behaviors like drawing and resizing
• ✓ Ensure your application can easily add new shapes in the future