diff --git a/Start_Windows/bintree.c b/Start_Windows/bintree.c
index c2493c9..b2230e1 100644
--- a/Start_Windows/bintree.c
+++ b/Start_Windows/bintree.c
@@ -16,7 +16,7 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFc
         return NULL;
     }
 
-    if (!root){
+    if (!root){                                                     //Neuen Node
         TreeNode *new = malloc(sizeof(TreeNode));
         if (!new){
             return NULL;
@@ -27,7 +27,7 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFc
             return NULL;
         }
 
-        memcpy(new->data, data, dataSize);
+        memcpy(new->data, data, dataSize);                          //data übertragen
         new->left = new->right = NULL;
 
         if (isDuplicate){
@@ -58,7 +58,39 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFc
 // push the top node and push all its left nodes.
 void *nextTreeData(TreeNode *root)
 {
-    
+    static StackNode *stack = NULL;
+    static int initialized = 0;
+
+    if (root != NULL) {                                         // Initialisierung: Stack leeren und mit root + linke elemente befüllen
+        while (stack != NULL) {
+            stack = pop(stack);
+        }
+        while (root != NULL) {
+            stack = push(stack, root);
+            root = root->left;
+        }
+        initialized = 1;
+    } else if (!initialized) {                                  // Noch nicht initialisiert und kein root übergeben
+        return NULL;
+    }
+
+    if (stack == NULL) {                                        //Ende
+        initialized = 0;
+        return NULL;
+    }
+
+    TreeNode *topNode = (TreeNode *)top(stack);
+    stack = pop(stack);
+
+    if (topNode->right != NULL) {
+        TreeNode *r = topNode->right;
+        while (r != NULL) {
+            stack = push(stack, r);
+            r = r->left;
+        }
+    }
+
+    return topNode->data;
 }
 
 // Releases all memory resources (including data copies).
diff --git a/Start_Windows/bintree.o b/Start_Windows/bintree.o
index 4a63186..2b6e015 100644
Binary files a/Start_Windows/bintree.o and b/Start_Windows/bintree.o differ
diff --git a/Start_Windows/bintreeTests.c b/Start_Windows/bintreeTests.c
index f637281..d779d3a 100644
--- a/Start_Windows/bintreeTests.c
+++ b/Start_Windows/bintreeTests.c
@@ -51,6 +51,28 @@ static void testAddToTreeNoData(){
 }
 
 
+static void testNextTreeDataInorderTraversal(){
+    TreeNode *root = NULL;
+    int values[] = {5, 3, 8, 1, 4};
+    int expectedInorder[] = {1, 3, 4, 5, 8};
+
+    for(int i = 0; i < 5; i++) {
+        root = addToTree(root, &values[i], sizeof(int), compareInt, NULL);          //Tree befüllen
+    }
+
+    void *data = nextTreeData(root);
+    TEST_ASSERT_NOT_NULL(data);
+
+    for(int i = 0; i < 5; i++){
+        TEST_ASSERT_NOT_NULL(data);
+        TEST_ASSERT_EQUAL_INT(expectedInorder[i], *(int*)data);
+        data = nextTreeData(NULL);                                                  // Nächstes Element
+    }
+
+    TEST_ASSERT_NULL(data);                                                         // Nach letzten Element muss NULL kommen
+}
+
+
 void setUp(void){
     
 }
diff --git a/Start_Windows/runBintreeTests.exe b/Start_Windows/runBintreeTests.exe
index bda5ff1..2a470c3 100644
Binary files a/Start_Windows/runBintreeTests.exe and b/Start_Windows/runBintreeTests.exe differ