Память под объекты через new

#include <iostream>
 
class A
{
public:
    int my;
};
 
 
int main()
{
    A* a = new A();
    A* b = new A();
    A* c;
    A* d;
 
    A f;
 
    std::cout << a << std::endl
              << b << std::endl
              << c << std::endl
              << d << std::endl;
 
    std::cout << std::endl;
 
    delete a;
    delete b;
}

    A* c = NULL;
    A* d = NULL;

    a->my = 4;
    f.my = 5;

    int* s = new int(6);
    std::cout << *s;

A* a = new A;
//и
A* a = new A();

std::cout << &a << std::endl
              << &b << std::endl
              << &c << std::endl
              << &d << std::endl;

A* a = new A();
A* b = new A;
A c;
A d;
std::cout << a << std::endl
          << b << std::endl
          << &c << std::endl
          << &d << std::endl;

int* a = new int; //значение a - мусор
int* b = new int(); //значение b == 0

class A
{
public:
    int my;
    A() : my(4){}
};

A* s = new A();

A* s = new A;

A a;
(&a)->my = 4;

std::cout << *a << std::endl << *b << std::endl;

#include <iostream>
 
class A
{
public:
    int my;
    A(){std::cout << "K" << std::endl;}
};
 
int main()
{
    A* a = new A;
    A* b = new A();
    std::cout << a -> my << std::endl << b -> my << std::endl;
    std::cout << std::endl;
 
    delete a;
    delete b;
 
    system("pause");
    return 0;
}

A():my(0){std::cout << "K" << std::endl;}

        
        int *pr = new int;
    int *pr1 = new int();
 
    std::cout << "pr = " << *pr << std::endl;
    std::cout << "pr1 = " << *pr1 << std::endl;
 
    delete pr;
    delete pr1;

A* a = new A();

A* a = new A;

A* a = new A();

A* a = new A;

#include <iostream>
 
class A
{
public:
    int my;
    ~A(){}
};
 
int main()
{
    A* a = new A;
    A* b = new A();
    std::cout << a -> my << std::endl << b -> my << std::endl;
    std::cout << std::endl;
 
    delete a;
    delete b;
 
    system("pause");
    return 0;
}