#ifndef TREE_H #define TREE_H #include class Tree { public: Tree(); ~Tree(); void print(std::ostream &) const; void insert(int val); private: struct Node { int data {}; Node * left {}; Node * right {}; ~Node(); }; Node * root {}; // helper function: static void print(std::ostream &, Node const * const); static void insert(int, Node *&); }; #endif