Chess

This program is an implementation of chess. The interface can be used by either a human or a chess engine. All moves go through the State class (state.h), which records the state of the game and the board.

• Interface for humans: bool State::move(string move_notation) => parse notation => bool State::move(Move input_move)
• Interface for engines: std::vector<Move> State::get_legal_moves() => pick a move => bool State::move(Move input_move)

Pieces are defined as a hierarchy of classes in piece.h. Each piece overrides std::vector<Move> get_legal_moves(const State& s) to return its own legal moves. Legal moves always depend on the state of the board: for example, a piece could be pinned to the king, and the king cannot move on squares under attack.

Quick start

Simply run make to compile and run.

Algebraic notation

Standard algebraic notation applies, with these exceptions:

• You cannot specify only the row or only the column (e.g. R3e6 or Rac6). If there are two possible pieces that can move to the same square, please use the whole coordinate (Re3e6, Ra6c6).
• You cannot use "O-O" and "O-O-O" for kingside/queenside castle. Simply specify the square the king wants to move to: Kg1
• You don't have to add "x" when capturing (e.g. Qxh4, Ba4xb5), although you can if you want to. The x will simply be ignored.

To resign or offer/accept a draw, just type "resign" or "draw".

Notation guide

Pieces: King = "K", Queen = "Q", Knight = "N", Bishop = "B", Rook = "R". You don't have to specify pawns with "P", although you can if you want to.

• Move a pawn: e4
• Move a pawn, unambiguous: e2e4
• Move the knight: Nb5
• Move the knight, unambiguous: Nd3b5
• Capture with a bishop: Bb5, Bxb5, Bf1xb5 ("x" is not necessary)
• Promote a pawn: h8=Q, h8=N, h7h8=N, h7xh8=N
• Castle queenside, white: Kc1
• Castle kingside, white: Kg1