Inheritance and Polymorphism

Runtime polymorphism

Polymorphism lets derived classes provide specialized behavior through virtual methods. Base pointers can call overridden methods at runtime.

#include <iostream>
using namespace std;

class Shape {
public:
    virtual double area() const { return 0; }
    virtual ~Shape() = default;
};

class Rectangle : public Shape {
    double w, h;
public:
    Rectangle(double w, double h) : w(w), h(h) {}
    double area() const override { return w * h; }
};

Design guidelines

• Use virtual destructors in polymorphic base classes.
• Favor composition when inheritance hierarchy grows too complex.
• Override methods with clear contracts and const-correctness.