C++ program printing a binary tree recursively preorder

👍 g++ -std=c++11 prt_binary_tree_preorder.cpp
👍 ./a.out
E
  D
    B
      A
        *
        *
      C
        *
        *
    *
  H
    F
      *
      G
        *
        *
    *
👍 cat prt_binary_tree.cpp 
#include <iostream>
using namespace std;

typedef char Item;
struct node{Item item; node *l, *r;};
typedef node *link;

void printnode(Item x, int h) {
  for (int i = 0; i < h; i++) 
    cout << "  ";
  cout << x << endl;  
}

void show(link t, int h) {
  if (t == 0) 
    {printnode('*', h); return;}
  printnode(t->item, h);
  show(t->l, h+1);
  show(t->r, h+1);
}

int main() {
  node a{'A'}; 
  node c{'C'}; 
  node b{'B', &a, &c}; 
  node d{'D', &b}; 

  node g{'G'}; 
  node f{'F', 0, &g}; 
  node h{'H', &f}; 
 
  node e{'E', &d, &h}; 

  show(&e, 0);
}

    

5.7 Recursive Binary-Tree Algorithm p251 of