public String toString() {
    String s;
    s = "[";
    if (size() > 0) s+= S[0];
    if (size() > 1)
      for (int i = 1; i <= size()-1; i++) {
	s += ", " + S[i];
      }
    return s + "]";
  }
//  Prints status information about a recent operation and the stack.
  public void status(String op, Object element) {
    System.out.print("------> " + op);   // print this operation
    System.out.println(", returns " + element); // what was returned
    System.out.print("result: size = " + size() + ", isEmpty = " + isEmpty());
    System.out.println(", stack: " + this);       // contents of the stack
  }
 /**
  * Test our program by performing a series of operations on stacks,
  * printing the operations performed, the returned elements and the
  * contents of the stack involved, after each operation.
  */
  public static void main(String[] args) {
    Object o;
    ArrayStack<Integer> A = new ArrayStack<Integer>();
    A.status("new ArrayStack<Integer> A", null);
    A.push(7);
    A.status("A.push(7)", null);
    o = A.pop();
    A.status("A.pop()", o);
    A.push(9);
    A.status("A.push(9)", null);
    o = A.pop();
    A.status("A.pop()", o);
    ArrayStack<String> B = new ArrayStack<String>();
    B.status("new ArrayStack<String> B", null);
    B.push("Bob");
    B.status("B.push(\"Bob\")", null);
    B.push("Alice");
    B.status("B.push(\"Alice\")", null);
    o = B.pop();
    B.status("B.pop()", o);
    B.push("Eve");
    B.status("B.push(\"Eve\")", null);
  }
}