I am mixing some C and C++ libraries and have only a single pointer available to do some work in a callback function. All I need to do is iterate through a vector. Here's a simplified, untested example:

bool call_back(void* data){
  done=...
  if (!done) cout << *data++ << endl;
  return done;
}

Note that this function is in an extern "C" block in C++. call_back will be called until true is returned. I want it to cout the next element each time it's called. data is a pointer to something that I can pass from elsewhere in the code (an iterator in the above example, but can be anything). Something from data will likely be used to calculate done. I see two obvious options to give to data:

1. Have data point to my vector.
2. Have data point to an iterator of my vector.

I can't use an iterator without having the .end() method available, right? I can't use a vector alone (unless maybe I start removing its data). I could make a struct with both vector and iterator, but is there a better way? What would you do?