//------------------- stack2.cpp -------------------------
//------------ source file for unit stack ----------------
//

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include "stack2.h"



//--------------------------- Iplementstion -----------------------------

//------------------ stack_init -------------------------

stack_type stack_init (void)
{
	stack_type S;
	S = NULL ;
	return S;
}

//------------------- stack_push (&S, x) ----------------

void stack_push (stack_type &S, stack_info_type x)
{
	stack_type q;

	q = (stack_type)malloc(sizeof(struct link_type));
	q->info = x;
	q->next = S ;
	S = q;
}

//-------------------- stack_pop (&S) ---------------------

stack_info_type stack_pop (stack_type &S)
{
	stack_type q ;
	stack_info_type x ;

	q = S ;
	S = S->next ;
	x = q->info ;
	free (q) ;

	return x ;
}

//-------------------- stack_top (S) ----------------------

stack_info_type stack_top (stack_type S)
{
	return (S->info);
}

//-------------------- stack_empty (S) --------------------

int stack_empty (stack_type S)
{
	return (S==NULL) ;
}

//-------------------- stack_show (S) ---------------------

void stack_show (stack_type S)
{
	stack_type S1 ;
	stack_info_type x ;

	S1 = stack_init () ;

	printf ("Top --> ") ;
	while (! stack_empty (S))
	{
		x = stack_pop (S) ;
		printf("%d   ",x);
		stack_push (S1, x) ;
	}

	while (! stack_empty (S1))
	{
		x = stack_pop (S1) ;
		stack_push (S, x) ;
	}
	printf (" // \n \n") ;
}