-SpriteManager* sprite_manager = 0;
-TileManager* tile_manager = 0;
-
-MouseCursor* mouse_cursor = 0;
-
-Font* gold_text;
-Font* blue_text;
-Font* gray_text;
-Font* white_text;
-Font* white_small_text;
-Font* white_big_text;
-
+MouseCursor* mouse_cursor = NULL;
+
+Font* gold_text = NULL;
+Font* blue_text = NULL;
+Font* gray_text = NULL;
+Font* white_text = NULL;
+Font* white_small_text = NULL;
+Font* white_big_text = NULL;
+