Tic-Tac-Toe Lab
COMP 150/170
10 Points
You are to write a C++ program that allows the user to play tic-tac-toe against the computer. A portion of the
program has been written for you and is available at \\cs1\Classes\Comp150\tictactoe.cpp.
The tic-tac-toe board is configured so that the different squares are numbered from 1 to 9. The example run
shown below illustrates how the game is to proceed (several moves are not shown). The user (X) moves first, and
the computer (O) responds. Play continues until either X wins, O wins, or there’s a tie.
The program uses a character array to represent the board:
char board[9] = {'1','2','3','4','5','6','7','8','9'};
The main and DisplayBoard functions have been written for you, but you
need to complete the other 3 functions to get the program to work
correctly. Below is a description of the functions:
1. DisplayBoard – takes the board its single (read-only) argument and
outputs the board to the screen.
2. CheckForWinner – takes the board as its single (read-only) argument and
returns 0 if there’s no winner yet, 1 if it’s a tie, 2 if X has won, and 3 if O has
won.
3. GetUserMove – takes the board as its only argument. It asks the user
where the X should be placed. If the user enters an illegal position (it is not
1-9 or there is already an X or O at the position), an error message should be
given, and the user should be continually prompted until a valid position is
given. The function should set the appropriate slot in the board array to the
position. Other than modify the board, this function does not return a
value.
4. GetComputerMove – takes the board as its only argument. It randomly
selects an empty square to place an O. Other than modify the board, this
function does not return a value.
The rand function should be used to choose a random number. You must add #include <cstdlib> to your program
to use rand. The rand function returns an integer in the range of 0 to RAND_MAX (a really large number). To limit
the number to a smaller range, you can use the mod operator:
int r = rand() % 100; // Return a random number between 0 and 99
Unfortunately, rand() will always return back the same set of random numbers each time the program is executed
unless, you give it a unique seed. This is typically done using the current date and time with the time function (you
must include <ctime> to access the time function). This call needs to only appear once in your main function:
srand(unsigned int(time(NULL))); // Initialize random seed
1 | 2 | 3
-----------
4 | 5 | 6
-----------
7 | 8 | 9
Enter your move: 1
X | 2 | 3
-----------
4 | 5 | 6
-----------
7 | 8 | 9
Computer is moving to 4
X | 2 | 3
-----------
O | 5 | 6
-----------
7 | 8 | 9
(Skipping…)
Enter your move: 5
X | 2 | 3
-----------
O | X | O
-----------
7 | 8 | X
X wins!!!
