c++ - Behaviour of std::list:begin() when list is empty

Question

Does the following give defined results in terms of the C++ standard?

std::list<int> myList;
std::list<int>::iterator myIter = myList.begin();    // any issues?
myList.push_back( 123 );
myIter++;                                  // will myIter point to the 123 I pushed?

I can test this out on the compiler I'm using... but I'd like a more definitive answer.

Answer 1

All standard iterator and container types behave the same in this regard:

§23.2.1 [container.requirements.general] p6

begin() returns an iterator referring to the first element in the container. end() returns an iterator which is the past-the-end value for the container. If the container is empty, then begin() == end();

And table 107 in §24.2.3 [input.iterators] demands that as a precondition for ++it, it shall be dereferenceable, which is not the case for past-the-end iterators (i.e., what you get from end()), as such you're treading into the dreaded domain of undefined behaviour.