无法弄清楚如何在c ++中清除链表？

Question

I'm trying to figure out how to clear a stack (in the form of a linked list). Linked lists aren't my forte; I don't understand them at all. Here's my code, can anyone shed some light onto why it's not working? When I try to call the method through a switch in main, it seems too get stuck in an infinite loop.

void stack :: clearStack()
{
if (isEmpty()== true)
{
    cout << "\nThere are no elements in the stack. \n";
}

else 
{
    node *current = top;
    node *temp;
    while(current != NULL);
    {
        current = temp -> next;
        delete current;
        current = temp;
    }
}

}

Answer 1

There are a few problems with that code. The first is that you dereference an uninitialized pointer ( temp ) the other that you delete the next pointer before you loop (and thereby pulling the carpet out under your own feet, so to say).

It's as simple as

node* next;
for (node* current = top; current != nullptr; current = next)
{
    next = current->next;
    delete current;
}

Oh, and don't forget to clear top when you're done.

Answer 2

You have not initialized temp . You need to set temp to the first node of the list. Inside the loop, cycle through the nodes and keep deleting them.

node *current = top;
node *temp = top; //    initialize temp to top
while(current != NULL);
{
    temp = temp -> next; // increase temp
    delete current;
    current = temp;
}

Answer 3

Think this is what you wanted to do:

node *current = top;
while(current != NULL);
{
    node *temp = current->next;
    delete current;
    current = temp;
}
top = null;

Answer 4

if (isEmpty()== true)
{
    cout << "\nThere are no elements in the stack. \n";
}
else 
{
    node *current = top;
    node *temp;
    while(current != NULL);
    {
        current = temp -> next;
        delete current;
        current = temp;
    }
}

That whole block can be replaced by:

while (top != nullptr)
{
    unique_ptr<node> p(top);
    top = top->next;
}

If the list is already empty, nothing is done. If it is non-empty, unique_ptr takes control of the memory management of the current top (which will delete it between loop iterations), move the top to the next . When top is NULL , everything is cleared and top is set to NULL .