// tStack2.h
#pragma once
#include <stdexcept>
using std::out_of_range;
    
template <class T>
class Stack
{
public:
    Stack(int size=10);
    ~Stack();
    void push(const T&);      // push element
    void pop();               // pop element
    T top() const;            // return top element
    bool isEmpty() const;     // return true if empty.
private:
    int nElems;               // current number of elements
    int maxElems;             // maximum number of elements
    T *elems;                 // elements
};

template <class T>
Stack<T>::Stack(int size): nElems(0), maxElems(size) 
{
    elems = new T[size];
}

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

template <class T>
bool Stack<T>::isEmpty() const
{
    return nElems<=0;
}

template <class T>
void Stack<T>::push(const T& elem)
{
    if (nElems>=maxElems)
        throw out_of_range("Stack<>::push(): full stack");
    elems[nElems++] = elem;
}

template <class T>
void Stack<T>::pop()
{
    if (nElems<=0)
        throw out_of_range("Stack<>::pop(): empty stack");
    nElems--;
}

template <class T>
T Stack<T>::top() const
{
    if (nElems<=0)
        throw out_of_range("Stack<>::top(): empty stack");
    return elems[nElems-1];
}