Classes and Objects

Bundling Data and Behavior

A class is a blueprint. An object is an instance of that blueprint.

class Rectangle {
public:
    double width;
    double height;

    double area() {
        return width * height;
    }

    double perimeter() {
        return 2 * (width + height);
    }
};

Rectangle r;
r.width  = 5.0;
r.height = 3.0;
cout << r.area();       // 15
cout << r.perimeter();  // 16

struct vs class

struct members are public by default; class members are private by default. Otherwise they're identical.

Your Task

Create a Circle class with:

• Public double radius
• double area() — returns PI * r * r
• double circumference() — returns 2 * PI * r

Use 3.14159265 for PI.