Tic Tac Toe... so close...

Hey guys, me again. Sorry to pester you so much, but once again I am stuck on an assignment. I'm supposed to create a game of tic tac toe that engages the user with a simple AI from the computer. Now, I have the whole thing mapped out except for one part...checking the win condition. Here's what code I have so far:

Code:

// TicTacToeVsAI.c.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "simpio.h"
#include <stdlib.h>

#define size 3
#define maxMoves 9

void initBoard(char board[size][size]); //Initializes the board for the first time
void clearBoard(char board[size][size]); //Initializes the board with 'empty' spaces
void printBoard(char board[size][size]); //Shows the current status of the board
bool checkWin(char board[size][size]); //Checks if anyone has won at the current time
bool TicTacToe(char board[size][size]); //Initializes the game
void GetMove(char board[size][size]); //Reads in and places the player's choice of location
void CompMove(char board[size][size]); //Causes the computer to make a move

main()
{
	char board[size][size];
	printf("To play the simple game of tic tac toe, enter the number of the space which \n");
	printf("you wish to place your mark in. When either player manages to get 3 in a row, \n");
	printf("diagonally, vertically, or horizontally, that player wins, otherwise,\nthe game is a draw.\n");
	initBoard(board);
	printBoard(board);
	clearBoard(board);
	TicTacToe(board);
}

void initBoard(char board[size][size])
{
	int row,column;
	int num=49; //Since this is going to initialize the board in such a way as to show
//the user how to play, we use num to label the squares of the board
	for (row=0;row<size;row++)
	{
		for (column=0;column<size;column++)
		{
			board[row][column]=num;
			num++;
		}
	}
}

void clearBoard(char board[size][size])
{	
	int row,column;
	for (row=0;row<size;row++)
	{
		for (column=0;column<size;column++)
		{
			board[row][column]=' '; //By filling the board with spaces, we are 'clearing' the board.
		}
	}
}

void printBoard(char board[size][size])
{
	int row,column;
	for (row=0;row<size;row++)
	{
		for (column=0;column<size;column++)
		{
			printf("%c", board[row][column]);
			if (column!=(size-1)) printf("|");
		}
		if (row!=(size-1)) printf("\n-+-+-\n");
	}
	printf("\n");
}

bool TicTacToe(char board[size][size])
{
	int player=1;
	int move=0; //The number of moves that have been made so far this game.
	while (move<=maxMoves)
	{
		if (player==1) GetMove(board);
		else CompMove(board);
		printBoard(board);
		player*=-1;
	}
	return true;
}
void GetMove(char board[size][size])
{
	int choice;
	bool flag=true;
	printf("Player, please enter your choice of location:  ");
	while (flag)
	{
		choice=GetInteger();
		switch (choice)
		{
		case 1: if (board[0][0]==' ') {board[0][0]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 2: if (board[0][1]==' ') {board[0][1]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 3: if (board[0][2]==' ') {board[0][2]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 4: if (board[1][0]==' ') {board[1][0]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 5: if (board[1][1]==' ') {board[1][1]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 6: if (board[1][2]==' ') {board[1][2]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 7: if (board[2][0]==' ') {board[2][0]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 8: if (board[2][1]==' ') {board[2][1]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 9: if (board[2][2]==' ') {board[2][2]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		}
	}
}

However, I need some help writing the checkWin function which checks the entire board for any win conditions. I'm completely stumped, and I have no idea how to go about this. Although code is appreaceated, even just some prompts on how I might go about this task would be greatly appreciated. Also, I was wondering if there was anyway to make the computer use that strategy where you make a triangle and block your opponent off in an attempt to stalemate the game. I've gotten the ai to the point where it's semi-smart, with the following code:

Code:

void NoLose(char board[size][size],int row,int column)
{
	if (board[row][column]==' ') board[row][column]='O';
	else
	{
		if ((row==2)&&(column==0)) NoLose(board,row-2,column+1);
		if ((row==0)&&(column==1)) NoLose(board,row+2,column+1);
		if ((row==0)&&(column==0)) NoLose(board,row+1,column+2);
		if ((row==0)&&(column==2)) NoLose(board,row+1,column-2);
		if ((row==1)&&(column==0)) NoLose(board,row+1,column+2);
		if ((row==1)&&(column==2)) NoLose(board,row+1,column-2);
		if ((row==2)&&(column==1)) NoLose(board,row-2,column+1);
		if ((row==2)&&(column==2)) NoLose(board,row-1,column-2);
	}

}

But it still gets killed by anyone with half a brain. Again, thanks in advance for any help

One thing, your construct:

Code:

switch (choice)
		{
		case 1: if (board[0][0]==' ') {board[0][0]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;
		case 2: if (board[0][1]==' ') {board[0][1]='X'; flag=false;} else printf("Invalid choice, try again\n"); break;

Could be probably be better written as:

Code:

int row, col;
choice--; /* convert to 0-8 internally */
row = choice/size;
col = choice%size;

if (board[row][col]==' ')
{
    board[row][col]='X';
    flag=false;
} else
    printf("invalid choice, try again\n");

Then you don't need to repeat the same code over and over.

As for the win condition, write code to iterate through each row, check for three of the same kind, write code to iterate through each column, check for three of the same kind, then check the two diagonals. You can use the same simple for loops as you did on Clear/Print/initboard.

To check the win condition, you have to see if any of the rows/columns/diagonals have the same value.

First row (or is it column? depends on how you interpret your matrix)

board[0][0] == board[0][1] && board[0][0] == board[0][2]

Well, think about how you win Tic Tac Toe. You need to get either three crosses or three naughts in a row, so just write a function to check for that? There aren't that many combinations - three horizontal, three vertical and two diagonal, so you could probably just go through and check all of them. If all three in the top row are the same symbol, then the appropriate player has won. If all three in the middle row are the same, then someone's won. And so on. There may be more efficient ways to do it, I'm not sure, but with only eight combinations to check anyway, it doesn't really matter.

But use a loop, instead of explicitly specifying each row/column offset, otherwise it defeats the purpose of having a definable size parameter.

But use a loop, instead of explicitly specifying each row/column offset, otherwise it defeats the purpose of having a definable size parameter.

I think either way would be fine. Moreover, explicitly specifying the row/column offset might be slightly faster than going through the loop (less JMP statements).

Originally Posted by Dante Shamest

I think either way would be fine. Moreover, explicitly specifying the row/column offset might be slightly faster than going through the loop (less JMP statements).

This is tic tac toe, not global thermonuclear war simulation.

Which is why I said either way would be fine, but it's not necessary to use a loop.

It is necessary to use a loop for two reasons.

1) The code without a loop is much longer and more convoluted, and leads to repeat code over and over.
2) He uses a loop for every other routine in the program, relying on the "size" define. Not using a loop would render this pointless.

Necessary means absolutely essential. As in, if he didn't used loops, it wouldn't work.

This is my Tic Tac Toe clone, which does not use loops to test the win condition, and it works perfectly.

Okay, my mistake. Let me rephrase, he should use a loop.

And, by posting your tic-tac-toe source, you are doing this guy's assignment for him.

Originally Posted by cwr

Okay, my mistake. Let me rephrase, he should use a loop.

Whether he should or not, it's up to him to decide. As you mentioned, using a loop would save code size, but that's about it.

And, by posting your tic-tac-toe source, you are doing this guy's assignment for him.

He's writing a console program in C.
My program in a Windows GUI program in C++.

True, looks good, by the way. I had a quick look at the source. I'd compile/run it, but I don't have Windows.

Thanks for the help guys! I now have a working iteration of the checkwin code, however I was just wondering if there was any way to make my comp smarter. Check the original post. I attempted using a conditional recursive function, but it messes up if someone puts their first position in your starting spot.

Originally Posted by Dante Shamest

Whether he should or not, it's up to him to decide. As you mentioned, using a loop would save code size, but that's about it.

Using a loop would also make it less likely that he would make a mistake when coding and make the code more readable and maintainable.