- Example

// cyclicReference.cpp
#include <iostream>
#include <memory>
struct Son;
struct Daughter;
struct Mother{
  ~Mother(){
    std::cout << "Mother gone" << std::endl;
  }
  void setSon(const std::shared_ptr<Son> s ){
    mySon=s;
  }
  void setDaughter(const std::shared_ptr<Daughter> d ){
    myDaughter=d;
  }
  std::shared_ptr<const Son> mySon;
  std::weak_ptr<const Daughter> myDaughter;
};
struct Son{
  Son(std::shared_ptr<Mother> m):myMother(m){}
  ~Son(){
    std::cout << "Son gone" << std::endl;
  }
  std::shared_ptr<const Mother> myMother;
};
struct Daughter{
  Daughter(std::shared_ptr<Mother> m):myMother(m){}
  ~Daughter(){
    std::cout << "Daughter gone" << std::endl;
  }
  std::shared_ptr<const Mother> myMother;
};
int main(){
  std::cout << std::endl;
  {
    std::shared_ptr<Mother> mother= std::shared_ptr<Mother>( new Mother);
    std::shared_ptr<Son> son= std::shared_ptr<Son>( new Son(mother) );
    std::shared_ptr<Daughter> daughter= std::shared_ptr<Daughter>( new Daughter(mother) );
    mother->setSon(son);
    mother->setDaughter(daughter);
  }
  std::cout << std::endl;
}