#include <iostream>
using namespace std;
int m = 42;
int n = 13;

// pass by value
void change(int z){
	z += 4;
	cout << z << endl;
}
// pass by reference
void changeptr(int *z){
	*z += 4;
}
void changeref(int &z){
	z += 4;
}
void yoiks(int **q){
	cout << " **q " << **q << endl;
	cout << " *q  " <<  *q << endl;
	cout << " q   " <<   q << endl;
	*q = &m;
}
void egads(int *&r){
   r = &n;
}
void main(){
   int *p;
   int x=3;
   int &r = x;
   p = &r;
   r = 2;
   cout << &r << " " << &x << endl;
   change(x);
   cout << x << endl;
   changeptr(&x);
   cout << x << endl;
   changeref(x);
   cout << x << endl;
   cout << "before yoiks &x = " << &x << endl;
   cout << "before yoiks *p = " << *p << endl;
   cout << "before yoiks  p = " <<  p << endl;
   cout << "before yoiks &p = " << &p << endl;
   yoiks(&p);
   cout << *p << endl;
   egads(p);
   cout << *p << endl;
}