SweetC++

#include<iostream>
#include<string>
using namespace std;

typedef unsigned int index;

template<class T>
class Element
{
public:
    T d;
    Element() {}
    Element(T& d) : d(d) {};
    template<class U> friend ostream& operator<<(ostream& buffer, const Element<U>& x);
    ~Element() {};
};

template<class T>
ostream& operator<<(ostream& buffer, const Element<T>& x)
{
    buffer << x.d;
    return buffer;
}

template<class T>
class Stack
{
private:
    Element<T>* S;
    index max_size;
    int top;
public:
    Stack(index N);
    bool isEmpty() const;
    bool isFull() const;
    void push(const Element<T>& x);
    Element<T> look_top();
    void pop();
    template<class U> friend ostream& operator<<(ostream& buffer, const Stack<U>& stack);
    ~Stack();
};

template<class T>
ostream& operator<<(ostream& buffer, const Stack<T>& stack)
{
    if (stack.isEmpty()) { buffer << "Stog je prazan."; return buffer; }
    else
    {
        for (int i = 0; i <= stack.top; i++) buffer << stack.S[i]<" ";
        return buffer;
    }
}

//konstruktori i destruktori

template<class T>
Stack<T>::Stack(index N) :max_size(N), top(-1)
{
    S = new Element<T>[N];
}

template<class T>
Stack<T>::~Stack()
{
    delete[] S;
}

template<class T>
bool Stack<T>::isEmpty() const
{
    return top == -1;
}

template<class T>
bool Stack<T>::isFull() const
{
    return top == max_size - 1;
}

template<class T>
void Stack<T>::push(const Element<T>& x)
{
    if (isFull()) return;
    else
    {
        top += 1;
        S[top] = x;
        return;
    }
}

template<class T>
Element<T> Stack<T>::look_top()
{
    if (isEmpty()) return NULL;
    else
    {
        return S[top];
    }
}

template<class T>
void Stack<T>::pop()
{
    if (isEmpty()) return;
    else
    {
        top--;
        return;

    }
}

int main()
{
    index n;
    cin >> n;
    Stack<int> stog(n);
    int unos;
    string naredba;
    while (1)
    {
        cout << "Stanje stoga: " << stog << endl;
        cin >> naredba;
        if (!naredba.compare("PUSH"))
        {
            cin >> unos;
            stog.push(unos);
            continue;
        }
        if (!naredba.compare("POP"))
        {
            stog.pop();
            continue;
        }
        if (!naredba.compare("exit"))
        {
            cout << "Izlaz" << endl;
            break;
        }
        cout << "Naredba nije poznata";
    }

    return 0;
}