abstrace_is_not_interface.cc

#include <iostream>

class A {
public:
    virtual int get_foo() = 0;
};

class B {
public:
    virtual int get_foo() { return 3; }
};

class C : public A, B {
};


int main(int argc, char** argv) {
    A* a = new C();

    std::cout << a->get_foo() << std::endl;
    return 0;
}