#include <iostream>
using namespace std;

void kswap(int *, int *);

void main(){
	int x;
	x = 3;
	cout << x << " " << &x << endl;
	int *p;
	p = &x;
	*p = 7;
	cout << x << endl;
	cout << " p " << p << " *p " << *p << endl;
	int* q, z;
	q = &z;
	*q = 13;
	cout << " z " << z << endl;
	*p = *q;
	cout << " x " << x << endl;
	x = 4; z = 123;
	p = q;
	cout << " p " << p << " q " << q << endl;
	cout << " x " << x << " z " << z << endl;
	*p = 42;
	cout << " x " << x << " z " << z << endl;
	p = new int(456);
	cout << " p " << p << " *p " << *p << endl;
	*p = 17;
	cout << *p << endl;
	delete p;
	// may work but gives invalid data
	cout << *p << endl;
	// avoids accidental usage of deleted pointer
	p = 0;
	// now crashes the program - a good thing!
	//cout << *p << endl;
	p = q;// p is still valid as a pointer.
	cout << *p << endl;
	x = 3; z = 78;
	kswap(&x, &z);
	cout << x << " " << z << endl;

}
void kswap(int *a, int *b){
	int t = *a;
	*a = *b;
	*b = t;
}