Pointer Wrapper

#include <iostream>
#include <string>

template<class T>
class ptr_wrapper
{
    T * ptr;

public:
    ptr_wrapper():ptr(nullptr) {}
    ptr_wrapper(T * ptr):ptr(ptr) {}
    ptr_wrapper(const ptr_wrapper& other):ptr(other.ptr) {}

    const T * get() const { return ptr; }
    T * get() { return ptr; }

    ptr_wrapper& operator=(const ptr_wrapper& other) { ptr = other.ptr; return *this; }

    bool operator==(const ptr_wrapper& other) const { return ptr == other.ptr; }
    bool operator!=(const ptr_wrapper& other) const { return ptr != other.ptr; }

    const T& operator*() const { return *ptr; }
    T& operator*() { return *ptr; }

    const T* operator->() const { return ptr; }
    T* operator->() { return ptr; }

    operator bool() const { return ptr != nullptr; }

    bool operator==(const T* other) const { return ptr == other; }
    bool operator!=(const T* other) const { return ptr != other; }
};

template<class T>
bool operator==(const T* p1, const ptr_wrapper<T>& p2)
{
    return p2 == p1;
}
template<class T>
bool operator!=(const T* p1, const ptr_wrapper<T>& p2)
{
    return p2 != p1;
}

int main()
{
    using namespace std;

    std::string * ptr = new std::string("hello");
    ptr_wrapper<std::string> a(ptr);
    const ptr_wrapper<std::string> b(a);

    a = b;

    cout << *ptr << " " << *a << " " << *b << endl;
    cout << ptr->length() << " " << a->length() << " " << b->length() << endl;

    if(ptr) cout << "ok ";
    if(a) cout << "ok ";
    cout << (a == ptr) << " " << (ptr == a) << " ";
    cout << (a != ptr) << " " << (ptr != a) << " ";
    cout << (a == b) << " " << (a != b) << " ";

    delete ptr;

    return 0;
}