internal and external iterator

What different between internal and external iterator?


external iterator:

It is a separate class that can step through its container/collection.

So you can control the logic to get the item what you want.

ex.

std::vector<int> v;
for(vint::iterator it=v.begin(), it!=v.end(); ++i)
    std::cout << *it << "\n";

internal iterator:

It is implemented with member functions to step through.

You only can get the items in turn, but it is more easy to use than external iterator.

ex.

MACRO_FOREACH(v)
{
    std::cout << v << "\n";
}