That's a good point. If you do have a situation where the number of objects is somewhat dynamic, you could use layers of protection such as (re)initializing the

That's a good point. If you do have a situation where the number of objects is somewhat dynamic, you could use layers of protection such as (re)initializing the unused objects to a known safe state, adding a flag as you mentioned, adding sentinel values to the end, and at the very least you do have the guarantee that you aren't running off into memory that was actually dedicated to another purpose and contains fundamentally different data. If you are doing something really dynamic, you could embed two linked lists (or an embedded list and a free index stack or even two packed stacks). The reason for stacks over lists is that lists can accidentally become cycles.