title: C++ Polymorphism: from parent class to child
body: <p>In C++ we can convert child class pointer to parent, but is there any way to convert it back: from parent, which was obtained from child, give child class back?</p>
  
  <p>I mean:</p>
  
  <pre><code>class Parent
  {
      ...
  };
  
  class Child : public Parent
  {
      ...
  };
  
  int main(int argc, char const *argv[])
  {
      Child* child = new Child();
      Parent* parent = child;
      Child* old_child = parent; // how to do this??
      return 0;
  }
  </code></pre>
  
  <p>Thank you for your answers.</p>