Why use iterators instead of array indices?

Question

Take the following two lines of code:

for (int i = 0; i < some_vector.size(); i++)
{
    //do stuff
}

And this:

for (som         


        

Answer 1

No one mentioned yet that one advantage of indices is that they are not become invalid when you append to a contiguous container like std::vector, so you can add items to the container during iteration.

This is also possible with iterators, but you must call reserve(), and therefore need to know how many items you'll append.