Data Structures - Implementing Stack using Class

  #include< iostream.h>
  #include< conio.h>
  #define SIZE 20
  class stack
  {
    int a[SIZE];
    int tos; // Top of Stack
    public:
       stack();
       void push(int);
       int pop();
       int isempty();
       int isfull();
  };
  stack::stack()
  {
    tos=0; //Initialize Top of Stack
  }
  int stack::isempty()
  {
    return (tos==0?1:0);
  }
  int stack::isfull()
  {
    return (tos==SIZE?1:0);
  }
  void stack::push(int i)
  {
    if(!isfull())
    {
      cout<<"Pushing "<< i<< endl;
      a[tos]=i;
      tos++;
    }
    else
    {
      cerr<<"Stack overflow error !
      Possible Data Loss !";
    }
  }
  int stack::pop()
  {
    if(!isempty())
    {
      cout<<"Popping "<< a[tos-1]<< endl;
      return(a[--tos]);
    }
    else
    {
      cerr<<"Stack is empty! What to pop...!";
    }
    return 0;
  }
  void reverse(stack s)
  {
    stack s2;
    while(!s.isempty())
    {
       s2.push(s.pop());
    }
    cout<<"Reversed contents of the stack..."<< endl;
    while(!s2.isempty())
    {
       cout<< s2.pop()<< endl;
    }
  }//end of fn.
  void main()
  {
    clrscr();
    stack s;
    s.push(1);
    s.push(2);
    s.push(3);
    reverse(s);
    getch();
  }