首先做出初始界面，让玩家选择游戏或退出，选择游戏则进入游戏函数，用二维数组做出棋盘，初始化并打印，初始化是将棋盘中的落子处全部变为空格，如果不初始化填充的是0，接着是玩家落子，电脑落子，每次落子只允许落在空格处，每一次落子后都要判断游戏状态，一共4种状态，“玩家赢”、“电脑赢”、“继续”、“平局”。从而需要一个判断函数，将赢的情况都列出(横三行、竖三列、对角线)，返回落子符号，没人赢即继续，平局即棋盘已满，除继续外三种情况直接结束游戏。电脑落子使用的是随机落子在空格处的方法。

void menu()
{
	printf("************************\n");
	printf("**** 1.play  2.exit ****\n");
	printf("************************\n");
}
void game()
{
	char ret = 0;
	char board[ROW][COL] = { 0 };
	InitBoard(board, ROW, COL);
	DisplayBoard(board, ROW, COL);
	while (1)
	{
		PlayerMove(board, ROW, COL);
		DisplayBoard(board, ROW, COL);		
		ret = IsWin(board, ROW, COL);
		if (ret != 'C')
			break;
		CompMove(board, ROW, COL);
		DisplayBoard(board, ROW, COL);		
		ret = IsWin(board, ROW, COL);
		if (ret != 'C')
			break;
	}
	if (ret == '*')
		printf("玩家赢！\n");
	else if (ret == '#')
		printf("电脑赢！\n");
	else
		printf("平局\n");
}
void test()
{
	int input = 0;
	srand((unsigned int)time(NULL));
	do 
	{
		menu();
		printf("请选择:>");
		scanf("%d", &input);
		switch (input)
		{
		case 1:
			game();
			break;
		case 2:
			printf("退出游戏\n");
			break;
		default:
			printf("选择错误，请重新选择");
			break;
		}
	} while (input!=2);
}
int main()
{
	test();
	return 0;
}

        具体函数的实现如下

void InitBoard(char board[ROW][COL], int row, int col)
{
	int i = 0;
	int j = 0;
	for (i = 0; i < row; i++)
	{
		for (j = 0; j < col; j++)
		{
			board[i][j] = ' ';
		}
	}
}

void DisplayBoard(char board[ROW][COL], int row, int col)
{
	int i = 0;
	int j = 0;
	for (i = 0; i < row; i++)
	{
		for (j = 0; j < col; j++)
		{
			printf(" %c ",board[i][j]);
			if (j < col - 1)
				printf("|");
		}
		printf("\n");
		if (i < row - 1)
		{
			for (j = 0; j < col; j++)
			{
				printf("---");
				if (j < col - 1)
					printf("|");
			}
			printf("\n");
		}
	}
}

void PlayerMove(char board[ROW][COL], int row, int col)
{
	int x = 0;
	int y = 0;
	printf("玩家走:>\n");
	while(1)
	{
		printf("请输入坐标:>");
		scanf("%d%d", &x, &y);
		if (x >= 1 && x <= row && y >= 1 && y <= col)
		{
			if (board[x - 1][y - 1] == ' ')
			{
				board[x - 1][y - 1] = '*';
				break;
			}
			else printf("该坐标被占用");
		}
		else printf("该坐标不合法，请重新输入\n");
	}
}
void CompMove(char board[ROW][COL], int row, int col)
{
	int x = 0;
	int y = 0;
	printf("电脑走:>\n");
	while (1)
	{
		x = rand() % row;
		y = rand() % col;
		if (board[x][y] == ' ')
		{
			board[x][y] = '#';
			break;
		}
	}
}
int IsFull(char board[ROW][COL], int row, int col)
{
	int i = 0;
	for (i = 0; i < row; i++)
	{
		int j = 0;
		for (j = 0; j < col; j++)
		{
			if (board[i][j] == ' ')
				return 0;
		}
	}
	return 1;
}
char IsWin(char board[ROW][COL], int row, int col)
{
	int i = 0;
	//横三行
	for (i = 0; i < row; i++)
	{
		if (board[i][0] == board[i][1] && board[i][1] == board[i][2] && board[i][2] != ' ')
			return board[i][0];
	}
	//竖三列
	for (i = 0; i < col; i++)
	{
		if (board[0][i] == board[1][i] && board[1][i] == board[2][i] && board[2][i] != ' ')
			return board[0][i];
	}
	//对角线
	if (board[0][0] == board[1][1] && board[1][1] == board[2][2] && board[1][1] != ' ')
		return board[1][1];
	if (board[0][2] == board[1][1] && board[1][1] == board[2][0] && board[2][0] != ' ')
		return board[1][1];
	//平局
	if (1 == IsFull(board, row, col))
		return 'Q';
	else
		return 'C';
}