[c++] Casting

#include <iostream>

int main()
{
  int *pointer= new int(1);

  std::cout << "before: " << pointer<< "\n";
  std::cout << "after: " << reinterpret_cast<int*>(reinterpret_cast<short>(pointer)) << "\n";

  delete pointer;
  std::cin.get();
}

main.cpp:8: error: cast from ‘int*’ to ‘short int’ loses precision

#include <iostream>

class A 
{
public:
	virtual void foo(){}
};

class B : public A
{
};

int main()
{
	A* ptr = new A();
	B* ptr2 = dynamic_cast<B *>(ptr);
	std::cout << "Old: " << ptr << std::endl;
	std::cout << "New: " << ptr2 << std::endl;
	return 0;
}

[~/dctest] % ./test
Old: 80b60f0
New: 0

#include <stdio.h>

class A
{
        int a;
public:
        A() {}
        virtual ~A() {}
};

class B
{
        int a;
public:
        B() {}
        virtual ~B() {}
};

class C : public A, B
{
        int a;
public:
        C() {}
        virtual ~C() {}
};

int main()
{
        C *c = new C();
        printf("%p\n%p\n%p\n",
                c,
                (A*)c,
                (B*)c); 
}

$ ./1
0x100100080
0x100100080
0x100100090
$ g++ --version 
i686-apple-darwin10-g++-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5664)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.