diff --git a/bintree.c b/bintree.c
index 32555c8..8687439 100644
--- a/bintree.c
+++ b/bintree.c
@@ -9,11 +9,48 @@
     * `nextTreeData`: Traversierung mit Hilfe des zuvor implementierten Stacks. */
 
 
+
+static TreeNode* createNode(const void* data, size_t dataSize) {
+    TreeNode* newNode = calloc(1, sizeof(TreeNode));
+    if(!newNode) return NULL;
+
+    newNode->data = malloc(dataSize);
+    if(!newNode->data) {
+        free(newNode);
+        return 0;
+    }
+    newNode->data = data;
+
+    return newNode;
+}    
 // Adds a copy of data's pointer destination to the tree using compareFct for ordering. Accepts duplicates
 // if isDuplicate is NULL, otherwise ignores duplicates and sets isDuplicate to 1 (or to 0 if a new entry is added).
-TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFctType compareFct, int *isDuplicate)
+//1. Fall: isDuplicate = NULL -> accepts
+//2. Fall: other            -> ignores duplicates and
+TreeNode *addToTree(TreeNode* root, const void* data, size_t dataSize, CompareFctType compareFct, int* isDuplicate)
 {
-    TreeNode newNode = createNode(data);
+    if(isDuplicate != NULL) {
+        *isDuplicate = 0;
+    }
+    if(!root) { //wurzerl == 0;
+        TreeNode* newNode = createNode(data, dataSize);
+        return newNode;
+    }
+    //wenn duplicate NUll -> doppelt hinzufügen
+    //
+
+    if(compareFct(data, root->data) < 0){
+        root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
+    } else if (compareFct(data, root->data) > 0) {
+        root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
+    } else if (compareFct(data, root->data) == 0) {
+        if(isDuplicate != NULL) {
+            *isDuplicate = 1;
+        } else {
+            root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
+        }
+    }
+            
 }
 
 // Iterates over the tree given by root. Follows the usage of strtok. If tree is NULL, the next entry of the last tree given is returned in ordering direction.
diff --git a/bintree.h b/bintree.h
index 25e16b2..721b677 100644
--- a/bintree.h
+++ b/bintree.h
@@ -3,7 +3,14 @@
 
 #include <stdlib.h>
 
-typedef int (*CompareFctType)(const void *arg1, const void *arg2);
+typedef int (*CompareFctType)(const void *arg1, const void *arg2); //ganz zahlen 
+
+void foo(void* ptr) {
+    unsigned int* casted_pointer = ptr;
+    unsigned int** a = &casted_pointer; //pointer pointer
+    unsigned int* b = casted_pointer; //pointer
+    unsigned int c = *casted_pointer; //wert
+}
 
 typedef struct node
 {
diff --git a/numbers.c b/numbers.c
index 9d44531..df702db 100644
--- a/numbers.c
+++ b/numbers.c
@@ -5,6 +5,15 @@
 #include "numbers.h"
 #include "bintree.h"
 
+CompareFctType compareFct(const void *arg1, const void *arg2) {
+    const unsigned int *entry1 = arg1;
+    const unsigned int *entry2 = arg2;
+
+    int result = *entry2 - *entry1;
+    
+    return result;
+}
+
 //TODO: getDuplicate und createNumbers implementieren
 /*  *   * Erzeugen eines Arrays mit der vom Nutzer eingegebenen Anzahl an Zufallszahlen.
   * Sicherstellen, dass beim Befüllen keine Duplikate entstehen.