C++ Variable initialization

main.cpp

#include <iostream>
using namespace std;

struct A {
	int x;
	A(int x_ = 0) { x = x_; }
};

struct B {
	int x;
	int* y;
	A* a;
	B(int x_, int* y_, A* a_) { x = x_; y = y_; a = a_; }
};

int y_ptr = 10;
int* y_ptr_ = &y_ptr;
A* a_ptr = &A(11);
B* b_ptr = &B(12, y_ptr_, a_ptr);

int y_new = 20;
int* y_new_ = &y_new;
A* a_new = new A(21);
B* b_new = new B(22, y_new_, a_new);

int main() {
	int y_loc = 30;
	int* y_loc_ = &y_loc;
	A* a_loc = &A(31);
	B* b_loc = &B(32, y_loc_, a_loc);

	int y_heap = 40;
	int* y_heap_ = &y_heap;
	A* a_heap = new A(41);
	B* b_heap = new B(42, y_heap_, a_heap);

	cout << b_heap->y << " -> " << *b_heap->y << " " << b_heap->a->x << endl;
	cout << b_loc->y  << " -> " << *b_loc->y  << " " << b_loc->a->x  << endl;
	cout << b_new->y  << " -> " << *b_new->y  << " " << b_new->a->x  << endl;
	cout << b_ptr->y  << " -> " << *b_ptr->y  << " " << b_ptr->a->x  << endl;
}