C++ Inheritance & Polymorphism

Base classes, virtual functions and override.

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class Dog : public Animal: Dog inherits from Animal.
Mark functions virtual in the base class so derived versions run through base pointers or references.
Use override in derived classes so the compiler checks you really override something.
A pure virtual function (= 0) makes the class abstract.
Give base classes a virtual destructor.

Key Takeaways: C++ Inheritance & Polymorphism

Mastering C++ Inheritance & Polymorphism helps you write clean and reliable C++ code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.

C++ Inheritance & Polymorphism Code Example

C++

#include <iostream>
#include <memory>
#include <vector>

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

class Circle : public Shape {
    double r;
public:
    explicit Circle(double r) : r(r) {}
    double area() const override { return 3.14159 * r * r; }
    const char* name() const override { return "Circle"; }
};

class Square : public Shape {
    double s;
public:
    explicit Square(double s) : s(s) {}
    double area() const override { return s * s; }
    const char* name() const override { return "Square"; }
};

int main() {
    std::vector<std::unique_ptr<Shape>> shapes;
    shapes.push_back(std::make_unique<Circle>(1));
    shapes.push_back(std::make_unique<Square>(3));
    for (const auto& s : shapes) std::cout << s->name() << ": " << s->area() << "\n";
    return 0;
}

Output