Fix compile error with MSVC 2013

[stockfish] / src / position.h

diff --git a/src/position.h b/src/position.h
index 3c7cf0f2a9cad7d33ebb33e664090bbdf4f8f517..86acd20d0eb7a174b779147f8e992dce9ff4a7c5 100644 (file)
--- a/src/position.h
+++ b/src/position.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,6 +22,7 @@
 
 #include <cassert>
 #include <cstddef>  // For offsetof()
+#include <string>
 
 #include "bitboard.h"
 #include "types.h"
@@ -174,7 +175,7 @@ public:
   Value non_pawn_material(Color c) const;
 
   // Position consistency check, for debugging
-  bool pos_is_ok(int* step = NULL) const;
+  bool pos_is_ok(int* step = nullptr) const;
   void flip();
 
 private: