#include <iostream.h>

const int MAXSTACK = 100;
const int TRUE = 1;
const int FALSE = 0;

// class declaration

// preconditions: requires that MAXSTACK the maximum size of the stack, be defined
//              : requires that TRUE be defined as a nonzero integer
//              : requires that FALSE be defined as 0

class Stack
{
  private:
    int top;   // top-of-stack position
    int num[MAXSTACK];

  public:
    Stack(void);   // constructor
    void push(int);
    int pop(void);
    int isempty(void);
    int isfull(void);

};

// implementation section

Stack::Stack()  // constructor
{
  top = -1;  // initialize the top-of-stack position
}

void Stack::push(int value)
{
  top++;   // increment the index stored in top
  num[top] = value;  // store the value
}

int Stack::pop(void)
{
  int topval;

  topval = num[top];  // retrieve the top element
  top--;              // decrement the index stored in top
  return(topval);
}

int Stack::isempty(void)
{
  if (top == -1)
    return(TRUE);
  else
    return(FALSE);
}

int Stack::isfull(void)
{
  if (top == MAXSTACK - 1)
    return(TRUE);
  else
    return(FALSE);
}

int main()
{
  Stack digits;    // define a Stack named digits
  int newnum;

  cout << "Enter as many digits as you wish, one per line"
       << "\nTo stop entering digits, enter a number greater than 9\n";
  while (1)
  {
    cout << "Enter a digit: ";
    cin >> newnum;
    if (newnum > 9)
      break;
    if (digits.isfull()) // check for overflow
    {
      cout <<"\nNo more storage allocation space"
	   << "\nThe last digit has not been entered on the stack"
	   << endl;
      break;
    }
    else
      digits.push(newnum); // push value onto the stack
  }

   // pop and display digits from the stack

 cout << "\nThe values popped from the stack are:\n";
 while(!digits.isempty())   // check for underflow
 {
    cout << digits.pop() << endl;
 }

 return 0;
}