Challenge 1: Reproducing Object Slicing — Possible Solution
====================================================================

#include <iostream>

class Shape {
public:
    virtual double area() { return 0; }
};

class Circle : public Shape {
public:
    double radius;
    Circle(double r) : radius(r) {}
    double area() override { return 3.14159 * radius * radius; }
};

int main() {
    Circle c(5.0);
    Shape s = c;  // sliced -- s is now just a plain Shape

    std::cout << s.area() << std::endl;

    return 0;
}

Output:

    0

WHY THIS WORKS AS AN ANSWER
------------------------------
Shape s = c; copies c by VALUE into a plain Shape variable -- since s's
static type is Shape, only the Shape-sized portion of c is copied;
Circle's own radius member and its override of area() are left behind
entirely. Calling s.area() therefore calls Shape::area() (returning 0)
rather than Circle::area(), exactly the "virtual dispatch silently
lost" symptom the chapter describes -- confirmed here since Circle's
own area() would have returned 78.5397... instead.