stack und teststack nicht final

stack.h

@@ -8,6 +8,13 @@ The latest element is taken from the stack. */
 #include <stdlib.h>
 
 //TODO: passenden Datentyp als struct anlegen
+typedef struct 
+{
+    void *data;
+    struct StackNode *next;
+    struct StackNode *prev;
+}StackNode;
+
 
 // Pushes data as pointer onto the stack.
 StackNode *push(StackNode *stack, void *data);