Programming in C++ Spring 2000 HW1

Programming In C++
Spring 2000

Homework #1 - Tic-Tac-Toe Game

Functions and 2-D Arrays

This assignment involves writing a tic-tac-toe playing program. The program can play against a human (which will require that you allow a human to enter moves) or against itself, but at least one of the players will be the computer.

Your program doesn't need to be very smart, the only requirement is that program win whenever it can (if there is a winning move it makes a winning move). It's not much harder to make the program also block a opponent win whenever possible (it requires the same logic as the requirement), but this is not required.

NOTE: The object of this assignment is to gain experience with writing C++ functions and dealing with C++ arrays. The object is not to develop the best tic-tac-toe program in the world.

The tic-tac-toe game board is represented in the progam as a 2 dimentional array of integers. The array is initially set to all 0s, this corresponds to an empty game board. Player 1 changes one of the array elements from a 0 to 1, player 2 changes a 0 to a 2.

Sample Code

There is some code to get you started, the code includes a function that draws a board using text output, the output looks like this:

      |   |
   ---|---|---
    X |   | O
   ---|---|---
    X | O |

Each time a move is made your program should call this function to print out the board. The prototype for this function is:


void drawgame( int board[3][3] );

The drawgame function, some support functions (functions that drawgame calls), and a sample main() that calls drawgame are included and documented in the file ttt.cpp.

There are also some suggestions to help you get started in the sample code (in comments at the bottom of the file).

You can use any compiler that we have access to (although it is expected that you code work with any compiler, not just your compiler), including MS Visual C++, g++, xlc, or any of the other Unix based C++ compilers on RCS.

What to turn in

You need to send us your documented (commented) source code, we don't need object files or executable programs. You should include (in the comments) a brief description of how your program works, any problems you had, things that don't work, or anything else you think might be helpful to the grader.

How to turn in your code

Email your code to cpp@cs.rpi.edu. You should receive confirmation that your project was received within 1 day.

Help, I can't figure out how to get started!

Some suggestions (there are also some in the sample code):

Start small: write and test a function that makes any move (could just find the first 0 in the array and replace it). Then write a program that plays this function against itself. Build from there...
Think about what kind of funtions you can write that can be used in more than one way, For example, don't write a function that checks only row 0 of the game board for a potential win - write a function that can check any row for a potential win.
User Interface: If you are comfortable using cin and cout, then start by writing a program that allows a human to be both players (lots of prompting and input required).
If you don't want to worry about reading in moves from a human - just focus on having the computer play both sides of the game.
Check the course home page for a HW1 FAQ, we will be updating it with questions and answers.