1 #include <stdio.h> 2 #include <stdlib.h> 3 #include "bin-trees.h" 4 5 static void real_preorder(tree_ptr root)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 17 void pre_order_traverse(tree_ptr root)18pre_order_traverse (tree_ptr root) 19 { 20 printf ("pre-order traversal, with recursion: \n"); 21 real_preorder (root) ; 22 printf ("\n"); 23 } 24