implement prefix, infix, and postfix binary tree print

1 files changed, 27 insertions, 5 deletions

diff --git a/trees.c b/trees.c
index dd38e0c..60de45a 100644
--- a/trees.c
+++ b/trees.c
@@ -28,14 +28,36 @@ struct tnode *bintree_insert(struct tnode *p, char *t)
     return p;
 }
 
-/* in-order tree print */
-void treeprint_inorder(struct tnode *p)
+/* CLR: pre-order / prefix tree print */
+void treeprint_prefix(struct tnode *p)
 {
     if (p != NULL)
     {
-        treeprint_inorder(p->left);
         printf("%4d %s\n", p->count, p->text);
-        treeprint_inorder(p->right);
+        treeprint_prefix(p->left);
+        treeprint_prefix(p->right);
+    }
+}
+
+/* LCR: in-order / infix tree print */
+void treeprint_infix(struct tnode *p)
+{
+    if (p != NULL)
+    {
+        treeprint_infix(p->left);
+        printf("%4d %s\n", p->count, p->text);
+        treeprint_infix(p->right);
+    }
+}
+
+/* LRC: post-order / postfix tree print */
+void treeprint_postfix(struct tnode *p)
+{
+    if (p != NULL)
+    {
+        treeprint_postfix(p->left);
+        treeprint_postfix(p->right);
+        printf("%4d %s\n", p->count, p->text);
     }
 }
 
@@ -51,7 +73,7 @@ int main(int argc, char **argv)
     for (i = 0; i < sizeof(tokens) / sizeof(char *); i++)
         root = bintree_insert(root, tokens[i]);
 
-    treeprint_inorder(root);
+    treeprint_infix(root);
 
     return 0;
 }