#include <iostream>
using namespace std;

void modprintarr(char *, int [], int);
void printarr(char *, int [], int);

void swapval(int a, int b);
void swapptr(int *a, int *b);
void swapref(int &a, int &b);

void main(){
	/* This is not a solution for variable
	sized arrays.  It will not compile.
	int x;
	cout << "enter size of array" << endl;
	cin >> x;
	int a[x];// will not compile
	*/

	int a[10];
	// what does this print?
	cout << a << endl;
	// a is the address of the start of the array!

	// proof
	cout << &a[0] << endl;

	// set up a pointer to the array
	int *p = a;
	for(int i=0; i<10; i++)
		p[i]=i;
	modprintarr(" after initializing p ",p,10);
	modprintarr(" after call to modifying print ",p,10);
	int *move = a;
	cout << move << endl;
	cout << ++move << endl;
	cout << &a[1] << endl;// prove move and &a[1] same
	int count = 50;
	for(move = a; move < a + 10; move++)
		*move = count--;
	//printarr("after using moving pointer",move,10); move beyond a
	printarr("after using moving pointer",a,10);

	// now show dynamic memory allocation of an array
	cout << "enter the size of the array" << endl;
	int x;
	cin >> x;
	p = new int[x];
	if(p != 0){
		for(int i = 0; i < x; i++)
			p[i] = i*i;
		printarr(" i squared using dynamic allocation",p,x);
		delete [] p;
	}
	else{
		cout << "allocation failed" << endl;
	}
    int xray = 555, zebra = -2;
	cout << "original " << endl;
	cout << xray << " " << zebra << endl;
	swapval(xray, zebra);
	cout << "after swapval " << endl;
	cout << xray << " " << zebra << endl;
	swapptr(&xray, &zebra);
	cout << "after swapptr " << endl;
	cout << xray << " " << zebra << endl;
	swapref(xray, zebra);
	cout << "after swapref " << endl;
	cout << xray << " " << zebra << endl;
}
void modprintarr(char *msg, int a[], int size){
	cout << msg << endl;
	for(int i = 0; i < size; i++)
		cout << a[i] << endl;
	a[3]=7777;//prove pass by reference
}
void printarr(char *msg, int a[], int size){
	cout << msg << endl;
	for(int *p = a; p < a + size; p++)
		cout << *p << endl;
}

// only swaps local copy
void swapval(int a, int b){
	int t = a;
	a = b;
	b = t;
}
// actually swaps using the address of the variable
void swapptr(int *a, int *b){
	int t = *a;
	*a = *b;
	*b = t;
}
// actually swaps by renaming the variable
void swapref(int &a, int &b){
	int t = a;
	a = b;
	b = t;
}