/* The following code example is taken from the book * "C++ Templates - The Complete Guide" * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002 * * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */#include <vector>#include <stdexcept>template <typename T>class Stack {  private:    std::vector<T> elems;     // elements  public:    void push(T const&);      // push element    void pop();               // pop element    T top() const;            // return top element    bool empty() const {      // return whether the stack is empty        return elems.empty();    }};template <typename T>void Stack<T>::push (T const& elem){    elems.push_back(elem);    // append copy of passed elem}template<typename T>void Stack<T>::pop (){    if (elems.empty()) {        throw std::out_of_range("Stack<>::pop(): empty stack");    }    elems.pop_back();         // remove last element}template <typename T>T Stack<T>::top () const{    if (elems.empty()) {        throw std::out_of_range("Stack<>::top(): empty stack");    }    return elems.back();      // return copy of last element}