Template stack

#include <iostream>
using namespace std;

template <class T>
class Stack;

template <class T>
class SNode{
  T _data;
  SNode<T>* _next;
  SNode(T data, SNode<T>* next){
    _data = data;
    _next = next;
  }
  friend class Stack<T>;
};

template <class T>
class Stack{
  SNode<T>* _top;
public:
  Stack();
  void push(T data);
  T pop();
  bool isEmpty()const;
  virtual ~Stack();
};

template <class T>
Stack<T>::Stack(){
 _top = (SNode<T>*)0;
}

template <class T>
void Stack<T>::push(T data){
  SNode<T>* temp = new SNode<T>(data,_top);
  _top = temp;
}



template <class T>
T Stack<T>::pop(){
  T val = _top->_data;
  SNode<T>* toDel = _top;
  _top = _top->_next;
  delete toDel;
  return val;
}

template <class T>
bool Stack<T>::isEmpty()const{
  return !_top;
}


template <class T>
Stack<T>::~Stack(){
  SNode<T>* toDel;
  while(_top){
    toDel = _top;
    _top = _top->_next;
    delete toDel;
  }
}

int main(){
  Stack<int> S;
  int i;
  for(i=100;i<2000;i+=10){
    S.push(i);
  }
  while(!S.isEmpty()){
    cout<<S.pop()<<" ";
  }
  cout<<endl<<"*******************************************"<<endl;
  for(i=100;i<2000;i+=10){
    S.push(i);
  }
  for(i=0;i<10;i++){
    cout<<S.pop()<<" ";
  }
  cout<<endl<<"*******************************************"<<endl;
  return 0;
}