// NET2006-5-Stakaray-Improved-RangeChecking.cpp
// an improved stack class
#include <iostream>
using namespace std;
////////////////////////////////////////////////////////////////
class Stack {
private:
	static const int MAX = 10;	// better approach: static means one and 
															// only one instance for all stack objects
	int nTop;										// Number of nTop of stack
	int anStack[MAX];						// Stack: array of integers
public:
	stack()											// Constructor
		{
		nTop = -1;					// -1 means that the stack is empty
		}	
	bool IsEmpty()
		{ return (nTop <= -1); }
	void IsFull()
		{ return (nTop >= MAX-1); }
	void Push(int nVarIn)				// Put number on stack
		{
		if (IsFull()) {						// Watch for array overrun
			cout << "Stack Full\n";
			return false;
			}
		else {
			anStack[++nTop] = nVarIn;
			return true;
			}
		}
	int Pop()										// Take number off stack
		{
		if (IsEmpty())						// Watch for array underrun
			cout << "Empty Stack\n";
		else
			return anStack[nTop--];
		}
}

////////////////////////////////////////////////////////////////
void main()
{
Stack s1;
s1.Push(11);
s1.Push(12);

Stack s2;
s2.Push(21);
s2.Push(22);

cout << "s1.1: " << s1.Pop() << endl;  //12
cout << "s1.2: " << s1.Pop() << endl;  //11

s2.Push(23);
s2.Push(24);

cout << "s2.1: " << s2.Pop() << endl;  //24
cout << "s2.2: " << s2.Pop() << endl;  //23

s1.Push(13);
s1.Push(14);
s1.Push(15);
s1.Push(16);

cout << "s1.3: " << s1.Pop() << endl;  //16
cout << "s1.4: " << s1.Pop() << endl;  //15
cout << "s1.5: " << s1.Pop() << endl;  //14
cout << "s1.6: " << s1.Pop() << endl;  //13

if (s1.IsEmpty())
	cout << "Stack 1 is empty";
else
	cout << "Stack 2 has remaining items.";

if (s2.IsEmpty())
	cout << "Stack 2 is empty";
else
	cout << "Stack 2 has remaining items.";
}