Medium Article: Making Iterators in C++

iterating-by-reference-example.cpp

for (auto& i : myContainer) {
  cout << "My item: " << i << endl;
}

iterator.cpp

class iterator {
  int state;
  
  // ...
  
  /* * * Implementing the expected iterator interface: * * */
  
  T operator*() { return get(); }
  iterator& operator++() { next(); return *this; }
  iterator operator++(int) { iterator temp(*this); next(); return temp; }
  iterator& operator--() { prev(); return *this; }
  iterator operator--(int) { iterator temp(*this); prev(); return temp; }
  bool operator!=(const iterator& other) const {
    return ref != other.ref || cmp(other.state);
  }
  bool operator==(const iterator& other) const {
    return !operator!=(other);
  }

  // Required implementations if you want to have const
  // and non const iterators working interchangeably:
  friend struct iterator_tpl::const_iterator<C,T,S>;

  // Comparisons between const and normal iterators:
  bool operator!=(const const_iterator<C,T,S>& other) const {
    return ref != other.ref || cmd(other.state);
  }
  bool operator==(const const_iterator<C,T,S>& other) const {
    return !operator!=(other);
  }
}