title: C++ and iterator invalidation
body: <p>So I'm going through Accelerated C++ and am somewhat unsure about iterator invalidation in C++. Maybe it's the fact that it is never explained how these iterators are constructed is the problem.</p>
  
  <p>Here is one example:</p>
  
  <p>Vector with {1,2,3}</p>
  
  <p>If my iterator is on {2} and I call an erase on {2} my iterator is invalid. Why? In my head, {3} is shifted down so the memory location of where {2} was so the iterator is still pointing to a valid element. The only way I would see this as being not true is if iterators were made before hand for each element and each iterator had some type of field containing the address of the following element in that container. </p>
  
  <p>My other question has to do with the statement such as "invalidates all other iterators". Erm, when I loop through my vector container, I am using one iterator. Do all those elements in the vector implicitly have their own iterator associated with them or am I missing something?</p>