How is insert iterator work in c++

Question

there is insert iterator in database template library or other library, Can someone tell me how it work ? Thanks!

Answer 1

It is a template class so you should be able to look it up in the implementation.

However, the idea is that it stores an iterator (current location) and a reference (pointer) to a container (that is being inserted in). Then it overloads operator= like this:

insert_iterator& operator= (typename Container::const_reference value)
{
    m_iter = m_container->insert(m_iter, value);
    ++m_iter;
    return *this;
}

So it requires a container that supports the insert method and at least a forward iterator, and has the standard typedefs (const_reference or perhaps value_type), so it can declare the right-hand type of its operator=.

The other output iterator operators (*, ++) just return *this.