Description

Introduction to Programming, PIC10A

E. Ryu

Fall 2016

Download the starter code main.cpp, ticTacToeBoard.h, and ticTacToeBoard.cpp. Do not modify

ticTacToeBoard.h. We have provided main.cpp to give you an idea of how we intend to use

the functions. ticTacToeBoard.cpp must not contain a main function.

You may not use global variables. We may take off up to 20% of the total marks for poor style;

make sure to name your variables reasonably, indent properly, and comment sufficiently. Submit

ticTacToeBoard.cpp.

Problem 1: (Tic-tac-toe) Write the function implementations for a program that plays the Tic-

tac-toe game on a 4×4 board. Player X goes first, and player O goes second.

The struct

struct ticTacToeBoard {

int curr_player ;

int points [4*4];

};

encodes the state of the game. curr_player==1 means it’s X’s turn to play. curr_player==-1

means it’s O’s turn to play. points[4*4] contains the moves made so far. An empty point has

value 0, a point marked X has value 1, and a point marked O has value -1.

The procedure

void printBoard ( ticTacToeBoard board );

prints the board. The definition of printBoard is provided, and it will clarify the meaning of

ticTacToeBoard.

The procedure

void initBoard ( ticTacToeBoard & board );

initializes the board. Since X goes first, initBoard must set board.curr_player to 1. Since

the board is empty at the beginning of the game, initBoard must set all values of the array

board.points to 0.

The predicate

bool isEmpty ( ticTacToeBoard board , int x , int y );

checks if the point (x,y) is empty and therefore available to play.

The procedure

void mark ( ticTacToeBoard & board , int x , int y );

1

marks the point (x,y). For example, if board.curr_player is -1 (so it’s O’s turn to play) and we

wish to mark (1,1) then board.points[0+4*0] must be assigned to -1.

The predicate

bool board full ( ticTacToeBoard board );

returns true if the board is full and false otherwise.

The function

int winner ( ticTacToeBoard board );

returns 0 if there is no winner, 1 if X is the winner, and -1 if O is the winner.

The function

int main ();

shows how we intend to use these functions. In particular, it shows that the points are referred to

with 1-based indexing. So if X marked (2,1) and O marked (3,4), the board will print to

| |X| | |

| | | | |

| | | | |

| | |O| |

You may not use any library aside from stream, string, and assert.

Hint. In writing winner you may find a helper function useful. Helper functions are functions

intended to aid other functions but not intended to be used by itself. For example, you could write

a function

bool winnerHelper ( ticTacToeBoard board , int player ) {

...

}

that returns true if the player is a winner and false otherwise. Then the winner will merely call

winnerHelper twice.