Get pointer to node in std::list or std::forward_list

Question

I am planning to use std::list in my code, I decided not to use std::forward_list, because for deletions (I figured) the whole list will have to traversed, O(N) complexity f

Answer 1

However, I cannot (or prefer not to) pass this iterator around in my code to access the data in the node.

Why not? Iterators are easy to use and are quite lightweight. A pointer isn't better in any way.

I am not sure if this iterator will be valid if the list is modified?

For list, any iterator will remain valid, even if the list is modified. Except, of course, if you erase the particular element that is the iterator points to. But that's kind of obvious, you can' expect to have an iterator (or pointer) to something that doesn't exist any more.

(vector is more dangerous. One small change to a vector can invalidate all its iterators.)

You can take a pointer to any individual element in the list.

list iterator it = find(l.begin(), l.end(), 7); // get an iterator
int * ptr = &*it; // get a pointer to the same element.

The pointer is similar to the iterator in many respects. But the iterator is a little more powerful. An iterator can be incremented or decremented, to access neighbouring elements in the list. And an iterator can be used to delete an element from the list. A pointer cannot do either of those things.

Both the iterator and pointer remain valid as long as that particular element isn't removed.