int* x = nullptr;
myclass* obj = nullptr;

template <class T>
class ptr {
    T* p_;
    public:
        ptr(T* p) : p_(p) {}

        template <class U>
        ptr(U* u) : p_(dynamic_cast<T*>(u)) { }

        // Without this ptr<T> p(NULL) would be ambiguous
        ptr(int null) : p_(NULL)  { assert(null == NULL); }
};

ptr(std::nullptr_t) : p_(nullptr)  {  }

pointer-literal:
nullptr

>>> None = 5
  File "<stdin>", line 1
SyntaxError: assignment to None
>>> type(None)
<type 'NoneType'>

#include <iostream>

struct B {};

struct A
{
    operator B*() {return 0;}
    operator bool() {return true;}
};

int main()
{
    A a;
    B* pb = 0;
    typedef void* null_ptr_t;
    null_ptr_t null = 0;

    std::cout << "(a == pb): " << (a == pb) << std::endl;
    std::cout << "(a == 0): " << (a == 0) << std::endl; // no warning
    std::cout << "(a == NULL): " << (a == NULL) << std::endl; // warns sometimes
    std::cout << "(a == null): " << (a == null) << std::endl;
}

(a == pb): 1
(a == 0): 0
(a == NULL): 0
(a == null): 1

void f(int);
void f(char*);

void g()
{
  f(0); //calls f(int)
}

void g()
{
  f(nullptr); //calls f(char*)
}