Iterating over unordered_map C++

From the cplusplus.com page about the begin member function of unordered_map (link):

Notice that an unordered_map object makes no guarantees on which specific element is considered its first element.

So no, there is no guarantee the elements will be iterated over in the order they were inserted.

FYI, you can iterate over an unordered_map more simply:

for (auto& it: B) {
    // Do stuff
    cout << it.first;
}