CPSC 231: Assignment 5 (Due Friday Nov. 15)

Weighting = 6%

A link to last summer's assignment 5 (The Game of Life) that you may or may not find useful.    You can also run the source code for the solution to this assignment by looking under the path: /home/231/assignments/assignment5/oldAssignment5.

The game of checkers

White player's side

Red player's side

Figure 1: The board

The game of checkers has been in existence for several hundred years and during that time many different variations have been developed.   However for most of these versions there exists a common set of rules:

1. It is a two player game
2. The game is played on a two-dimensional board (8x8) that consists of 64 squares alternating between 32 light and 32 dark squares.  The board is positioned so that each player will have a light square on the right corner closest to him or her (Figure 1).
3. Each player has 12 checker "pieces".  One player will control 12 red pieces while the other player controls 12 white pieces.
4. A player's pieces are positioned on the 12 dark squares that are closest to the player.
5. The red player moves first.  After the first move the two players will then alternate moves.
6. Checker pieces can only move along the dark squares.  This means that pieces can only move diagonally (Figure 2)

Yes	No
Figure 2: How checker pieces move

7. Checker pieces can only be moved onto empty squares, a player cannot move one of his or her pieces directly onto a square that is already occupied by another piece. 
8. A piece that is making a non-capturing move (the move does not involve a "jump") can only move one square at a time (Figure 3).

Yes	No
Figure 3: Pieces only move one diagonal at a time.

9. Checker pieces can only move forward (away from the player) unless the piece has been crowned (see point No. 12 below).  In the example shown in Figure 4 below, the uncrowned white piece can only move "down", in a direction away from the white player.

Yes	No
White player's side	White player's side
Red player's side	Red player's side
Figure 4: Uncrowned pieces can only move forward

10. Pieces that are making a capturing move (a jump) leaps moves over an opponent's piece landing in a straight diagonal line on the other side.  Only one piece can be captured in a single jump (Figure 5a)  but multiple jumps are allowed on a single turn  and thus allowing multiple pieces to be captured in a single turn (Figure 5b).

Single jump	Combining single jumps
Figure 5a: A single jump for a turn	Figure 5b: Combining multiple jumps for a turn

11. A captured piece is removed from the board.  The effect of the single and the multiple jumps from the previous step is illustrated in Figure 6, below where the pieces captured from the jumps shown in Figure 5 have been removed from the board.

Effect of single jump	Effect of multiple jumps
Figure 6a: Single capture	Figure 6b: Multiple captures

12. A player's piece is "crowned" and becomes a king when it reaches the row furthest from that player (Figure 7a).  In an actual checkerboard one piece is stacked on top of the other piece to designated that it has been crowned.  In Figure 7b a crowned piece is indicated by the addition of a star.

White player's side	White player's side
Red player's side	Red player's side
Figure 7a: White piece moves to the  row furthest from the white player	Figure 7b: This piece gets crowned and becomes a king (indicated with a star)

13. Kings can move diagonally like regular pieces but can move forward as well as backward (Figure 8).

Figure 8: Kings can move either forwards or backwards in a diagonal fashion one square at a time.

14. Kings have the ability to combine jumps in both directions (forward and backward) during a single turn.

In addition to these generic rules there are some rules that are specific to your assignment:

1. Mandatory jumping will not be enforced: If during a player's turn, one of his or her pieces is in a position to jump another player's piece and capture it, your checker game will not force that player to jump the piece.
2. Determining a win: A player wins the game when the opposing player no longer has any checker pieces left.  

Your version of checkers

For this assignment you are to implement a non-graphical game of checkers.  Checker pieces will be represented by alphabetic characters:

	Red player	White player
Uncrowned piece	r	w
Crowned piece (king)	R	W

The board will be represented with the ASCII vertical bar "|" and the ASCII horizontal bar "-".    Each row and column will be numbered from 1 to 8.  The row nearest the top of the screen will be numbered "1" and successive rows below that will be numbered sequentially numbered from 2 to 8.  The left most column will be numbered "1" and successive rows to the right of this column will be numbered sequentially from 2 to 8.  Thus the grid representing the checker board with the pieces in the starting positions will look like the grid shown in Figure 9.

		1		2		3		4		5		6		7		8
		-		-		-		-		-		-		-		-
1	|		|	r	|		|	r	|		|	r	|		|	r	|
		-		-		-		-		-		-		-		-
2	|	r	|		|	r	|		|	r	|		|	r	|		|
		-		-		-		-		-		-		-		-
3	|		|	r	|		|	r	|		|	r	|		|	r	|
		-		-		-		-		-		-		-		-
4	|		|		|		|		|		|		|		|		|
		-		-		-		-		-		-		-		-
5	|		|		|		|		|		|		|		|		|
		-		-		-		-		-		-		-		-
6	|	w	|		|	w	|		|	w	|		|	w	|		|
		-		-		-		-		-		-		-		-
7	|		|	w	|		|	w	|		|	w	|		|	w	|
		-		-		-		-		-		-		-		-
8	|	w	|		|	w	|		|	w	|		|	w	|		|
		-		-		-		-		-		-		-		-

Figure 9: Displaying the board with a grid.

To draw the grid you are allowed to use the code provided in  the example program grids.p which can be found in Unix under /home/231/assignments/assignment5.  Although it isn't mandatory for you to use the code in this program for your assignment, your checkers program MUST use the system of  numbered grids shown in Figure 9 to display the board.  Failure to display the checker board using this grid will result in the loss of two letter steps e.g., "A" to "B+".  JT: This may seem harsh but imagine you are the TA trying to determine if the 75+ checkers games that he or she will get from the students are working without the benefit of this grid. 

The starting pattern of checker pieces must be read in from a file.  Your checkers games will be playable only by human opponents.  You do not have to write a program that will have computer controlled players.  A player moves a piece by typing in the row and column coordinates of the piece that he or she wishes to move.  Assuming that the player has selected a square containing a piece that belongs to him or her, then the player will type in the row and column coordinates of square that the player wishes to move the piece to.

Grading

D- version 

The student has invested a considerable effort in the assignment but the program but it does not compile.

D version

The student has invested a considerable effort in the assignment, the program compiles but does it not fulfill any of the specifications listing in the assignment.

C- version

The program can read the information for the checker board containing only a single piece from the file called "board1"¹ from a file.

• This is a single player version of checkers (the program doesn't distinguish players from move to move).
• The user can select a piece on the board (by typing in the row, column coordinates for that piece).
• The user can move the piece and the program will check that the destination is actually one of the squares on the checker board (row and column coordinates are values between 1 and 8 inclusive).  If the player selects a row and/or column value outside of this range, then the program will indicate to the player that pieces can only be moved within the bounds of the board and it will continue prompting the player for a destination until a valid set of row/column coordinates has been entered.
• The program displays the updated values for the board from turn to turn i.e., after each move has been made. 
• The program will continue prompting the user to move the piece around the board until the person indicates that he or she wishes to quit the game.
• The player controls the game through a series of menu options which can look similar to the menu below:

  Checker game options:

  (M)ove a piece

  (Q)uit game

C version

Fulfills all the requirements of the C- version plus:

The program will check that pieces are only moved diagonally.  If the player tries to move a piece in a non-diagonal fashion, then the program will indicate that pieces can only be moved diagonally and continue prompting the user for the destination coordinates until a valid set of values has been typed in.

C+ version

Fulfills all the requirements of the C version plus:

The program will check that pieces are only moved forward.  If the player tries to move a piece backward then the program will indicate that uncrowned pieces can only be moved forward and it will continue prompting the user for the destination coordinates until a valid set of values has been typed in.

B- version

Fulfills all the requirements of the C+ version plus:

When a piece reaches the far row it will be crowned and become a king (indicated by changing the piece from a lower case letter to a capital letter).  Crowned pieces are given the ability to move forwards as well as backwards in a diagonal fashion.

B version

Fulfills all the requirements of the B- version plus:

• The program can read in the starting positions for a full board from the file "board2".¹
• The program allows for two-player mode.  This means that the program will start the first turn of the game with the red player going first.  It will then alternate between the red and the white player from turn to turn.  If a player selects a piece of the incorrect color then the program will indicate that the player has selected a piece of the wrong color and continue prompting the user to enter a set of coordinates for a correctly colored piece.

B+ version

Fulfills all the requirements of the B version plus:

Players can capture pieces of the opposing color.  When the player enters in a set of destination coordinates, then the program will determine if this move results in the capture of an opposing piece.  The program should check to see if attempted jumps are valid by checking that pieces only jump diagonally and that an opposing piece will actually be captured by the jump.  If the jump and capture is valid, then the opposing piece is removed from the board and the player's piece is moved to the appropriate location on the board.   If it is not valid then the program will indicate that this is not a valid jump and it will continue prompting the player until a valid set of destination coordinates have been entered.  This version of the game need only handle the case where single jumps are made for each turn.  Multiple jumps in a turn will be handled by the A- version of this assignment.

A- version

Fulfills all the requirements of the B+ version plus:

In situations where multiple jumps are possible the player can indicate to the program that he or she wishes to perform a multiple jump by entering (0,0) for the row/column coordinates.  The program will then prompt the user to input the coordinates for each square that the player wishes to jump to until the player types in (0,0) again to indicate that he or she has completed the multiple set of jumps. The program will then check this path in order to determine if it is a valid series of jumps.  If this is a valid set of multiple jumps then the appropriate opposing pieces will be removed from the board and the player's piece will be moved to the coordinates of the final destination square.  If this is not a valid set of multiple jumps then the program will indicate to the player that the path that they provided is not valid for a multiple jump and it will prompt the person to enter in a valid set of destination coordinates.

A version

Fulfills all the requirements of the A- version plus:

The program can determine when a player has won the game.  At the end of each player's turn, the program will check to see if the opposing player has any pieces left and if this is the not case then the program will indicate that the player has won and the game will end.

A+ version

Fulfills all the requirements of the A version plus:

Add two extra menu options (see below) to allows the player to save and load games.  When a game is saved, your program will write out to a text file the positions of the pieces at that point in the game.  The format and appearance of this file will be similar to the one for board2 and consist of upper and lower case alphabetic characters representing the red pieces "R" and "r" and the white pieces "W" and "w" and spaces for empty squares.  The load game option will read in the position of the pieces from a previously saved game and allow the player to continue playing the game from that point onward.  

Checker game options:

(M)ove a piece

(L)oad a game

(S)ave game

(Q)uit game

^{1 You are of course allowed to change the names of these files.}

Other requirements

1. Good coding style and documentation:  They will play a role in determining your final grade for this assignment.  Your grade can be reduced by a full step e.g., "A" to "A-" for poor style.

Learning Objectives

Understanding and using two-dimensional arrays in Pascal.  Learning how to read information from files.