function pop is done

stack.c

@@ -22,12 +22,6 @@ return newNode;
 // freed by caller.)
 StackNode *pop(StackNode *stack)
 {
-
-}
-
-// Returns the data of the top element.
-void *top(StackNode *stack)
-{
     if (stack == NULL)
         return NULL;
 
@@ -36,6 +30,14 @@ free(stack);
     return next;
 }
 
+// Returns the data of the top element.
+void *top(StackNode *stack)
+{
+if (stack == NULL)
+  return NULL;
+return stack->data;
+}
+
 // Clears stack and releases all memory.
 void clearStack(StackNode *stack)
 {