The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <iterator>
// class template for insert iterator for associative and unordered containers
template <typename Container>
class asso_insert_iterator
: public std::iterator <std::output_iterator_tag,
typename Container::value_type>
{
protected:
Container& container; // container in which elements are inserted
public:
// constructor
explicit asso_insert_iterator (Container& c) : container(c) {
}
// assignment operator
// - inserts a value into the container
asso_insert_iterator<Container>&
operator= (const typename Container::value_type& value) {
container.insert(value);
return *this;
}
// dereferencing is a no-op that returns the iterator itself
asso_insert_iterator<Container>& operator* () {
return *this;
}
// increment operation is a no-op that returns the iterator itself
asso_insert_iterator<Container>& operator++ () {
return *this;
}
asso_insert_iterator<Container>& operator++ (int) {
return *this;
}
};
// convenience function to create the inserter
template <typename Container>
inline asso_insert_iterator<Container> asso_inserter (Container& c)
{
return asso_insert_iterator<Container>(c);
}