Tic-Tac-Toe

//Lets play a game of tic-tac-toe
//Created by Zell Faze
//Available freely under the CC-0 License
#include <iostream>
#include <string>
#include <sstream>
#include <stdlib.h>
using namespace std;

void outputBoard(int board[][3]);
void initBoard(int board[][3]);
int  checkWinners(int board[][3]);
void makeAIMove(int board[][3]);

int main() {
  int       board[3][3];
  string    inputStr;
  bool      gameDone = false;
  int       selectedMove;

  //Initialise the board to empty
  initBoard(board);
  srand(time(NULL));

  //Main game loop
  while (gameDone == false) {
    outputBoard(board);

    bool inputValid = false;
    int x, y;
    do {
      cout << "Where would you like to move? (1-9) ";
      getline(cin, inputStr);
      stringstream(inputStr) >> selectedMove;

      //Lets start assuming the input is valid (kinda odd I know)
      inputValid = true;

      if ((selectedMove < 0) || (selectedMove > 9)) {
        cout << "That move is invalid." << endl;
        inputValid = false;
      }

      x = (selectedMove / 3);
      y = (selectedMove % 3) - 1;

      if (board[x][y] != 0) {
        cout << "That move is invalid." << endl;
        inputValid = false;
      }
    } while (inputValid == false);

    board[x][y] = 1;

    int winner;
    winner = checkWinners(board);

    if (winner == 0) {
      makeAIMove(board);
    }

    winner = checkWinners(board);

    if (winner != 0) {
      gameDone = true;
      outputBoard(board);
      cout << "Player " << winner << " won the game!";
    }
  }

  return 0;
}

void initBoard(int board[][3]) {
  for (int x = 0; x < 3; x++) {
    for (int y = 0; y < 3; y++) {
      board[x][y] = 0;
    }
  }

  return;
}

void outputBoard(int board[][3]) {

  for (int x = 0; x < 3; x++) {
    for (int y = 0; y < 3; y++) {

      //Output the state
      switch (board[x][y]) {
        case 0:
          cout << " ";
          break;
        case 1:
          cout << "X";
          break;
        case 2:
          cout << "O";
          break;
      }

      //Output the col seperator
      if (y == 2) {
        cout << endl;
      } else {
        cout << "|";
      }
    }

    //Output the row seperator
    if (x != 2) {
      cout << "-----" << endl;
    }
  }

  cout << endl;
  return;
}

int checkWinners(int board[][3]) {
  int player = 0;

  //Check for horizontal wins
  for (int x = 0; x < 3; x++) {
      player = board[x][0];
      if (player == 0) {
        continue;
      }

      bool possible = true;
      for (int y = 1; y < 3; y++) {
        if (board[x][y] == player) {
          continue;
        } else {
          possible = false;
          break;
        }
      }

      if (possible == true) {
        return player;
      }
  }

  //Check for vertical wins
  for (int y = 0; y < 3; y++) {
      player = board[0][y];
      if (player == 0) {
        continue;
      }

      bool possible = true;
      for (int x = 1; x < 3; x++) {
        if (board[x][y] == player) {
          continue;
        } else {
          possible = false;
          break;
        }
      }

      if (possible == true) {
        return player;
      }
  }

  //Check for diagonal wins
  player = board[0][0];
  if ((board[1][1] == player) && (board[2][2] == player)) {
    return player;
  }

  player = board[0][2];
  if ((board[1][1] == player) && (board[2][0] == player)) {
    return player;
  }

  return 0;
}

void makeAIMove(int board[][3]) {
  int x, y;
  bool validMove = false;

  do {
    x = rand() % 3;
    y = rand() % 3;

    if (board[x][y] == 0) {
      validMove = true;
    }
  } while(validMove == false);

  board[x][y] = 2;
}