Stripping off extended class properties when copying

cut_off.cpp

#include <iostream>
using namespace std;

class Foo {
public:
    int a;
    Foo(int a) : a(a) {
    }
    virtual void print() {
        cout << "  I am Foo: " << a << "\n";
    }
};

class Bar : public Foo {
public:
    int b;
    Bar(int a, int b) : Foo(a), b(b) {
    }
    void print() {
        cout << "  I am Bar: " << a << ", " << b << "\n";
    }
};

int main(int argc, char** argv) {
    cout << "Initializing Foo & Bar\n";
    Foo foo(13);
    Bar bar(13, 37);
    foo.print(); // I am Foo: 13
    bar.print(); // I am Bar: 13, 37

    cout << "Calling &bar as Foo\n";
    ((Foo*)(&bar))->print(); // I am Bar: 13, 37


    cout << "Copying bar to a Foo object, stripping off Bar\n"; 
    ((Foo)(bar)).print(); // I am Foo: 13

    return 0;
}