Templated Stack Linked List - stack

Question

I have written a templates stack linked list for an assignment I have to complete. When I run it, it prints out the first element, but then crashes. Any ideas on what could be going wrong? I have a feeling it might be the pop function, but its so basic, I'm not sure what is even wrong.
template<typename T>
struct StackNode
{
T data;
StackNode* next;
StackNode(T t, StackNode* ptr);
~StackNode();
};
template <typename T>
StackNode<T>::StackNode(T t, StackNode* ptr = nullptr)
:data(t), next(ptr)
{
}
template <typename T>
StackNode<T>::~StackNode()
{
delete next;
}
template<typename T>
struct LinkedStack
{
LinkedStack();
LinkedStack(const StackNode<T> &s);
~LinkedStack();
bool isEmpty();
void push(const T& t);
void pop();
T top();
StackNode<T>* head;
int numElements;
};
template <typename T>
LinkedStack<T>::LinkedStack()
: head(nullptr), numElements(0)
{
}
template<typename T>
LinkedStack<T>::LinkedStack(const StackNode<T> &s)
: head(nullptr), numElements(0)
{
for (auto t = s.head; t; t = t->next)
push(t->item);
}
template<class T>
LinkedStack<T>::~LinkedStack()
{
while (!isEmpty())
{
pop();
}
}
template<typename T>
bool LinkedStack<T>::isEmpty()
{
if (numElements > 0)
{
return false;
}
else
{
return true;
}
}
template<typename T>
void LinkedStack<T>::push(const T& t)
{
head = new StackNode<T>(t, head);
numElements++;
}
template<typename T>
void LinkedStack<T>::pop()
{
if (isEmpty())
{
cout << "Stack is empty." << endl;
}
else
{
StackNode<T>* oldnode = head;
head = head->next;
numElements--;
delete oldnode;
}
}
template<typename T>
T LinkedStack<T>::top()
{
if (isEmpty())
{
cout << "Stack is empty..." << endl;
}
else
{
return head->data;
}
}
int main()
{
LinkedStack<string> x;
x.push("Test");
x.push("One");
x.push("Two");
x.push("Three");
cout << "Now popping all elements of the stack:" << endl;
while (x.isEmpty() == false)
{
cout << x.top() << endl;
x.pop();
}
}

Answer 1

When you delete a node, you also delete the node it points to :
template <typename T>
StackNode<T>::~StackNode()
{
delete next;
}
When you pop an item, you delete the whole linked list as the deletion propagate from a node to another. The segfault is raised after deleting the last node, your programs try to delete nullptr.
The delete statement in the pop function is enough. No need to delete Stacknode.next as you do not assign it with the new keyword
I've successfully runned your code after removing the problematic delete.