Tic-tac-toe Tutorial (Step 4)

ttt_4.cpp

#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;

/** 
 * Draw a 3x3 tic-tac-toe board with row and column labels
 * The cell data in board will be interpreted as follows:
 *   1 = owned by 'x'
 *   2 = owned by 'o'
 *   all other values = empty
 *
 * @param  int[3][3] board The current state of each board cell
 * @return void
 */
void drawBoard(int board[][3]) {
  cout << "  " << "  A   B   C  " << endl;
  cout << "  " << "+---+---+---+" << endl;
  for (int row = 0; row < 3; row++) {
    cout << row << " ";
    for (int col = 0; col < 3; col++) {
      switch (board[row][col]) {
        case 1: cout << "| " << "x" << " "; break;
        case 2: cout << "| " << "o" << " "; break;
        default:cout << "| " << " " << " "; break;
      }
    }
    cout << "|" << endl;
    cout << " " << " " << "+---+---+---+" << endl;
  }
}

/** 
 * Get the next move from the player, and make sure that the
 * desired move is valid. Validity means:
 *   - column value is within bounds [A, B, C]
 *   - row value is within bounds    [0, 1, 2]
 *   - the selected cell is empty    board[row][col] == 0
 * Once input has been validated, update the board.
 *
 * @param  int[3][3] board  The current state of the board
 * @return void
 */
void nextPlayerMove(int board[][3]) {
  bool col_valid;         // Flag for column validity
  bool row_valid;         // Flag for row validity
  char col_c;             // container for the character value of the column
  int  col;               // container for the integer value of the column
  int  row;               // container for the integer value of the row

  cout << "Your turn. Where would you like to move next?" << endl;
  cout << "Type your move as two characters separated by a space (ex: A 1)" << endl;
  
  do {
    col_valid;         // assume correct input until proven wrong via tests later
    row_valid;         // ...
    // Obtain input from the user (one character for column, one int for row)
    cin >> col_c >> row;
    
    // Validate the provided column value
    if      (col_c == 'a' || col_c == 'A') { col = 0; }
    else if (col_c == 'b' || col_c == 'B') { col = 1; }
    else if (col_c == 'c' || col_c == 'C') { col = 2; }
    else {
      cout << "! Invalid column value entered. Your choices are: [A, B, C] " << endl;
      col_valid = false;
    }
    
    // Validate the provided row value
    if (row < 0 || row > 2) {
      cout << "! Invalid row value entered. Your choices are: [0, 1, 2] " << endl;
      row_valid = false;
    }
    
    // Ensure that the choice corresponds to an empty cell
    if (row_valid && col_valid && board[row][col] != 0) {
      cout << "! That cell is not empty. Please try a different cell " << endl;
      col_valid = false;
      row_valid = false;
    }
  } while (!col_valid || !row_valid);

  // Update the board with the user's latest choice
  board[row][col] = 1;  // user is always 'x'
}



int main (int argc, char* argv[])
{
  // State variables
  //
  // Board:
  //     0   1   2
  //   +---+---+---+
  // 0 |   |   | x | x = board[0][2]
  //   +---+---+---+
  // 1 |   |   |   |
  //   +---+---+---+
  // 2 |   |   |   |
  //   +---+---+---+
  //
  // Each board square will be in one of three possible
  // states:  0=empty, 1=owned by 'x', 2=owned by 'o'.
  int board[3][3] = {};

  // Flag to determine whether or not the game is finished
  // false: game should end: someone has won or there are no more valid moves
  // true:  game may continue
  bool gameIsValid = true;

  // Flag to determine whose turn it is
  // false: it is the computer's turn to make a move
  // true:  it is the player's turn to make a move
  bool playerTurn = true;


  /* Game Flow */

  // 1. determine who goes first
  playerTurn = rand() % 2; // coin flip

  // 2. Enter the main game "loop"
  while (gameIsValid) {
    // a. draw the board
    drawBoard(board);
    
    // b. current player makes a move
    //    the logic here depends on whether or not the
    //    computer or the player is the current player
    if (playerTurn) {
      // Some function for asking the user what the next move should be...
      nextPlayerMove(board);

    } else {
      // Some function for determining what the next move should be...
      //nextComputerMove(board);
    }

    drawBoard(board);
    return 0;
    
    // c. check if the current player has just won

    // d. swap current player
    
  }

  // 3. print final game result message

}