Can I increment an iterator by just adding a number?

Question

Can I do normal computations with iterators, i.e. just increment it by adding a number?

As an example, if I want to remove the element vec[3], can I just do this:

std::vector<int> vec;
for(int i = 0; i < 5; ++i){
      vec.push_back(i);
}
vec.erase(vec.begin() + 3); // removes vec[3] element

It works for me (g++), but I'm not sure if it is guaranteed to work.

Answer 1

It works if the iterator is a random access iterator, which vector's iterators are (see references). The STL function advance can be used to advance a generic iterator, but since it doesn't return the iterator, I tend use + if available because it looks cleaner.

Answer 2

It works with random access iterators. In general you may want to look at std::advance which is more generic. Just be sure to understand performance implications of using this function template.