Matt D - 1 year ago 49

C++ Question

In a linked list, in what order are nodes removed by the destructor?

Does it go first to last or last to first?

Answer Source

Either order is possible -- the only way to be certain is to inspect the specific implementation you're using.

In general, for a singly-linked list, I would expect a first-to-last ordering because it's easier to implement and a bit more efficient:

```
LinkedList::~LinkedList()
{
Node *node = mHead;
while (node) {
Node *next = node->mNext;
delete node;
node = next;
}
}
```

Versus a last-to-first ordering, which for a singly-linked list will generally require some sort of recursion:

```
void deleteList(Node *node)
{
if (node == 0) {
return;
}
deleteList(node->mNext);
delete node;
return;
}
LinkedList::~LinkedList()
{
deleteList(mHead);
}
```

So again -- the only way to be sure is to look at your linked list implementation.