A generic Stack data structure based upon linked lists.

linked_stack.cpp

#include <iostream>
#include <memory>

using namespace std;

template <typename T>
class LinkedStack
{
	class Node
	{
	public:
		Node(T value) : data(value), next(nullptr) {}
		T data;
		shared_ptr<Node> next;
	};

	shared_ptr<Node> top;

public:
	LinkedStack() : top(nullptr) {}
	~LinkedStack();

	void push(T data);
	void pop();
	T *peek();
	int length();

	template <typename... Args>
	void push(Args... data)
	{
		(push(data), ...);
	}
};

template <typename T>
LinkedStack<T>::~LinkedStack()
{
	while (length() != 0)
	{
		pop();
	}
}

template <typename T>
int LinkedStack<T>::length()
{
	int size = 0;
	shared_ptr<Node> current = top;
	while (current)
	{
		size++;
		current = current->next;
	}
	return size;
}

template <typename T>
void LinkedStack<T>::push(T data)
{
	shared_ptr<Node> node(new Node(data));
	node->next = top;
	top = node;
}

template <typename T>
void LinkedStack<T>::pop()
{
	if (length() == 0)
	{
		return;
	}
	shared_ptr<Node> temp = top;
	top = temp->next;
}

template <typename T>
T *LinkedStack<T>::peek()
{
	if (length() == 0)
	{
		return nullptr;
	}
	return &(top->data);
}

int main()
{
	LinkedStack<int> *stack = new LinkedStack<int>();
	stack->push(16, 32, 64);
	std::cout << "Added 3 elements to stack" << std::endl;
	std::cout << "Stack Length: " << stack->length() << std::endl;
	std::cout << "Top Element: " << *stack->peek() << std::endl;
	stack->pop();
	stack->pop();
	std::cout << "Stack Length after Pops: " << stack->length() << std::endl;
	stack->pop();
	if (stack->peek() == nullptr)
	{
		std::cout << "Stack is empty." << std::endl;
	}
	delete stack;
	return 0;
}