/////////////////////mydefs2b.h////////////////

class node {		// class node outside Istack, needs friend
	friend class Istack;
	
	int data;
	node* next;
	node(int, node* ); 	// builder-initializer prototype
};

class Istack {		// linked list implementation
	node* top;
public:
	void init(int Nitems = 100) 
		{ top = NULL; }
	void push(int x) 
		{ top = new node(x, top); }
	int pop();			// Not defined here, later
	bool isempty() 
		{ return( top == NULL ); }
	bool isfull() 
		{ return( FALSE ); }	// Never Full
};

////////////////////////stack2b.cc/////////////
#include <assert.h>
// Linked list implementation of stacks.

node :: node(int d, node* n)
{
	data = d;
	next = n;
}
int Istack :: pop()
{
	assert( !isempty() );
	int temp = top -> data;		// get data
	node* oldtop = top;		// point to old
	top = top -> next;			// unlink old
	delete oldtop;				// discard
	return temp;
}

/////////////////////stackmain2b.cc//////////
#include <iostream.h>
void main()
{
	Istack s1, s2;
	int i;

	s1.init(500);
	s2.init();
	
	for( i = 0; i < 20; i++ ) {
		s1.push(i);
	}

	for( i = 0; i < 20; i++ ) {
		cout << s1.pop() << ' ';
	}
	cout << endl;
	
	s2.push(10);
	i = s2.pop();
}
/*
19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
*/