Mark const methods const.

[slidingtile] / sliding_tile_lib.h

diff --git a/sliding_tile_lib.h b/sliding_tile_lib.h
index 89c65c1ee51c7b3ecc2a0e6c561c2a2e6c78a9db..4d6c0151e45d622c05e3a0ed98a528bbf80405c5 100644 (file)
--- a/sliding_tile_lib.h
+++ b/sliding_tile_lib.h
@@ -8,7 +8,8 @@ const int BOARD_SIZE = BOARD_DIM * BOARD_DIM;
 
 struct Board {
   signed char board[BOARD_SIZE];
-  bool is_valid();
+  bool is_valid() const;
+  signed char hole() const;
 };
 std::istream& operator>>(std::istream& is, Board& board);