diff --git a/bintree.c b/bintree.c
index 5f5fbbc..1201de5 100644
--- a/bintree.c
+++ b/bintree.c
@@ -34,14 +34,16 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFc
 	int cmp = compareFct(data, root->data);
 
 	if (cmp == 0){
-
+	    if (isDuplicate != NULL) {
+	        *isDuplicate = 1;
+	    }
 		/*
 		if (isDuplicate == NULL){
 			root->right = addToTree(root->right, data, dataSize, compareFct, NULL);
 			return root;
 		}*/
 
-		*isDuplicate = 1;
+
 		return root;
 	}
 
@@ -60,13 +62,39 @@ 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)
 {
-	if (root != NULL){
-
-
-
-
+    static StackNode *stack = NULL;
+    static TreeNode* currentNode = NULL;
+    void* result;
 
+	if(stack==NULL && root != NULL){
+        currentNode = root;
+	 	while(currentNode != NULL){
+			stack = push(stack,currentNode);
+			currentNode = currentNode->left;
+   		}
 	}
+
+    if (stack == NULL)return NULL;
+
+    currentNode = top(stack);
+	stack = pop(stack);
+
+
+    result = currentNode->data;
+
+		if(currentNode->right != NULL){
+			currentNode = currentNode->right;
+
+			while(currentNode != NULL){
+				stack = push(stack,currentNode);
+				currentNode = currentNode->left;
+ 	    	}
+		}
+
+
+
+
+	return result;
 }
 
 // Releases all memory resources (including data copies).
@@ -103,8 +131,8 @@ int compareFct(const void *a, const void *b){
     unsigned int A = *(unsigned int *)a;
     unsigned int B = *(unsigned int *)b;
     int result= 0;
-	if(A>B)result = -1;  //logik vertauscht?
-	if(B>A)result = 1;  //logik vertauscht?
+	if(A>B)result = 1;
+	if(B>A)result = -1;
 	if(A==B)result = 0;
 
     return result;
diff --git a/bintreeTests.c b/bintreeTests.c
new file mode 100644
index 0000000..83cb0f1
--- /dev/null
+++ b/bintreeTests.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include "unity/unity.h"
+#include "bintree.h"
+
+void setUp(void){}
+void tearDown(void){}
+
+void TEST_BINTREE{
+
+
+}
+
+
+
+int main(){
+    UNITY_BEGIN();
+
+    printf("\n============================\nbintree tests\n============================\n");
+
+    //RUN_TEST();
+    //RUN_TEST();
+    //RUN_TEST();
+
+    return UNITY_END();
+}
\ No newline at end of file