Fixing clear

src/main.c

@@ -5,12 +5,28 @@
 
 int main(void) {
   Tree tree = {NULL};
-  printf("Tree size: %d\n", tree_size(tree.root));
+
+  // Some test insertions
   tree_insert(&tree, 1);
   tree_insert(&tree, 2);
   tree_insert(&tree, 3);
+
+  // Check size and print inorder
   printf("Tree size: %d\n", tree_size(tree.root));
+  tree_inorder(tree.root);
+
   printf("Tree contains 2: %d\n", tree_contains(tree.root, 2));
-  // tree_clear(&tree.root); // Something is fishy here
+
+  // Clear the tree
+  tree_clear(&tree);
+
+  // Check if the tree is really empty
+  if (tree.root == NULL) printf("Tree is empty\n");
+  else printf("Tree is not empty: %d\n", tree.root->data);
+
+  // Check size and print inorder
+  printf("Tree size: %d\n", tree_size(tree.root));
+  tree_inorder(tree.root);
+
   return 0;
 }

src/tree.c

@@ -65,17 +65,34 @@ int tree_remove(Node **node, int data) {
   return 0;
 }
 
-int tree_clear(Node *node) {
+void tree_clear(Tree *tree) {
+  if (tree->root == NULL)
+    return;
+
+  node_clear(tree->root);
+  tree->root = NULL;
+}
+
+void node_clear(Node *node) {
   if (node == NULL)
-    return 0;
+    return;
 
   if (node->left != NULL)
-    tree_clear(node->left);
+    node_clear(node->left);
+
   if (node->right != NULL)
-    tree_clear(node->right);
+    node_clear(node->right);
 
   free(node);
-  return 0;
+}
+
+void tree_inorder(Node *node) {
+  if (node == NULL)
+    return;
+
+  tree_inorder(node->left);
+  printf("%d ", node->data);
+  tree_inorder(node->right);
 }
 
 int tree_size(Node *node) {

src/tree.h

@@ -1,4 +1,5 @@
-#pragma once
+#ifndef TREE_H
+#define TREE_H
 
 #include <stdbool.h>
 #include <stdio.h>
@@ -17,8 +18,25 @@ struct Tree {
 };
 typedef struct Tree Tree;
 
+// Insert some data into the tree
 int tree_insert(Tree *tree, int data);
+
+// Remove some data from the tree
 int tree_remove(Node **node, int data);
-int tree_clear(Node *node);
+
+// Clear the tree (this wraps node_clear)
+void tree_clear(Tree *tree);
+
+// Recursively clear from a certain node
+void node_clear(Node *node);
+
+// Get the size of the tree
 int tree_size(Node *node);
+
+// Check if the tree contains some data
 bool tree_contains(Node *node, int data);
+
+// Print the tree in order
+void tree_inorder(Node *node);
+
+#endif // TREE_H