diff --git a/bintree.c b/bintree.c
index 60daca8..9aa8baa 100644
--- a/bintree.c
+++ b/bintree.c
@@ -4,8 +4,8 @@
 
 
 //TODO: binären Suchbaum implementieren
-/*  * `addToTree`: fügt ein neues Element in den Baum ein (rekursiv),
-    * `clearTree`: gibt den gesamten Baum frei (rekursiv),
+/*  * `addToTree`: fügt ein neues Element in den Baum ein (rekursiv),       Done
+    * `clearTree`: gibt den gesamten Baum frei (rekursiv),                  Done
     * `treeSize`: zählt die Knoten im Baum (rekursiv),
     * `nextTreeData`: Traversierung mit Hilfe des zuvor implementierten Stacks. */
 
@@ -20,8 +20,9 @@
 
     // self declared functions
     TreeNode        *addToTreeRec   (TreeNode *currentNode, TreeNode *newNode, CompareFctType compareFct, int *isDuplicate);
-    TreeNode        *clearTreeRec   (TreeNode *currentNode);
+    void            clearTreeRec    (TreeNode *currentNode);
     void            clearNode       (TreeNode *node);
+    void            treeSizeRec     (const TreeNode *currentNode, unsigned int *nodeCount);
 
 
 // Adds a copy of data's pointer destination to the tree using compareFct for ordering. Accepts duplicates
@@ -69,7 +70,7 @@ TreeNode *addToTreeRec(TreeNode *currentNode, TreeNode *newNode, CompareFctType
         }
         else
         {
-            isDuplicate = 1;
+            *isDuplicate = 1;
         }
     }
 
@@ -96,7 +97,7 @@ void clearTree(TreeNode *root)
 }
 
 
-TreeNode *clearTreeRec(TreeNode *currentNode)
+void clearTreeRec(TreeNode *currentNode)
 {
     if (currentNode != NULL)
     {
@@ -122,7 +123,23 @@ void clearNode(TreeNode *node)
 
 // Returns the number of entries in the tree given by root.
 unsigned int treeSize(const TreeNode *root)
-{
+{   
+    unsigned int amountOfNodes = 0;
 
+    
+    treeSizeRec(root, &amountOfNodes);
+
+
+    return amountOfNodes;
+}
+
+void treeSizeRec(const TreeNode *currentNode, unsigned int *nodeCount)
+{
+    if (currentNode != NULL)
+    {
+        treeSizeRec(currentNode->left, nodeCount);
+        *nodeCount++;
+        treeSizeRec(currentNode->right, nodeCount);
+    }
 }