1#include <stdio.h> 2#include <stdlib.h> 3#include "bin-trees.h" 4 5static void 6real_preorder (tree_ptr root) 7{ 8 if (root == NULL) 9 return; 10 11 printf ("%d ", root->data); 12 real_preorder (root->left); 13 real_preorder (root->right); 14} 15 16 17void 18pre_order_traverse (tree_ptr root) 19{ 20 printf ("pre-order traversal, with recursion: \n"); 21 real_preorder (root) ; 22 printf ("\n"); 23} 24