/*********************************************************
 * From C PROGRAMMING: A MODERN APPROACH, Second Edition *
 * By K. N. King                                         *
 * Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
 * All rights reserved.                                  *
 * This program may be freely distributed for class use, *
 * provided that this copyright notice is retained.      *
 *********************************************************/

/* stack1.c (Chapter 19, page 488) */

#include <stdio.h>
#include <stdlib.h>
#include "stack.h"

#define STACK_SIZE 100

static int contents[STACK_SIZE];
static int top = 0;

static void terminate(const char *message)
{
  printf("%s\n", message);
  exit(EXIT_FAILURE);
}

void make_empty(void)
{
  top = 0;
}

bool is_empty(void)
{
  return top == 0;
}

bool is_full(void)
{
  return top == STACK_SIZE;
}

void push(int i)
{
  if (is_full())
    terminate("Error in push: stack is full.");
  contents[top++] = i;
}

int pop(void)
{
  if (is_empty())
    terminate("Error in pop: stack is empty.");
  return contents[--top];
}