Teste de Dynamic Cast de Classes

#include <iostream>
#include <ostream>

class base {
    public:
    virtual ~base( ) {}
};

class derived : public base {};
class most_derived : public derived {};
class other : public base {};

int main( )
{
    base* b = new derived;
    std::cout << "A " << b << "\n";
    std::cout << "B " << dynamic_cast<most_derived*>(b) << "\n"; // Null pointer
    dynamic_cast<derived&>(*b); // OK
    std::cout << "C " << b << "\n";
    std::cout << "D " << dynamic_cast<other*>(b) << "\n"; // Null pointer
    derived* d = new most_derived;
    std::cout << "E " << d << "\n";
    b = d;
    std::cout << "F " << b << "\n";
    b = dynamic_cast<base*>(d); // OK, but dynamic_cast<> is unnecessary.
    std::cout << "G " << b << "\n";
}