Code:
#include <iostream>
#include <vector>
using namespace std;
// global constants
const char X = 'X';
const char O = 'O';
const char EMPTY = ' ';
const char TIE = 'T';
const char NO_ONE = 'N';
// game function's prototypes
void displayBoard(const vector<char>& board); // function that displays the game board
char choosePiece(); // function to let the user choose their pieces
char winner(const vector<char>& board); // determines the game winner
char firstMove(const char& player1, const char& player2); // function that determines who makes the first move
int playerOneMove(const vector<char>& board, const char player1); // returns the move of player1
int playerTwoMove(const vector<char>& board, const char player2); // returns the move of player2
int main()
{
// vector that holds the game board
vector<char> board(9, EMPTY); // there are only 9 positions in a tic-tac-toe board so a vector with 9 elements is fine
//and initialized all elements with the EMPTY char
// show the instructions
// this is how the board would look like
cout << "\n\n" << 0 << " | " << 1 << " | " << 2 << endl;
cout << "---------" << endl;
cout << 3 << " | " << 4 << " | " << 5 << endl;
cout << "---------" << endl;
cout << 6 << " | " << 7 << " | " << 8 << endl;
cout << "\n\nThe above is the game board" << endl;
cout << "To put your piece in the center of the game board, enter number 4."
<< "\nTo put your piece elsewhere in the board, then enter its corresponding position"
<< "\nnumber as illustrated in the diagram above" << endl;
char player1, player2;
player1 = choosePiece();
// player1 has chosen its piece now chose the opposite piece of player1 for player2
if (player1 == 'X')
{
player2 = 'O';
}
else {
player2 = 'X';
}
cout << "\n\nPlayer 1's piece is " << player1 << endl;
cout << "Player 2's piece is " << player2 << endl;
char turn; // variable to store whose turn it is
turn = firstMove(player1, player2); // who goes first, returns either X or O
cout << "\n\nGood luck to both of the players!" << endl;
// while nobody has one the game and its not a tie
while (winner(board) == NO_ONE)
{
int move;
displayBoard(board);
if (turn == player1)
{
move = playerOneMove(board, player1);
board[move] = player1;
turn = player2;
}
else
{
move = playerTwoMove(board, player2);
board[move] = player2;
turn = player1;
}
}
displayBoard(board);
cin.ignore();
cout << "\n\nPress Enter...";
cin.get();
cout << "\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n" << endl;
cout << "\n " << winner(board) << " has won the game!" << endl;
cin.ignore();
cout << "Press Enter to Exit...";
cin.get();
}
void displayBoard(const vector<char>& board)
{
cout << "\n\n" << board[0] << " | " << board[1] << " | " << board[2] << endl;
cout << "---------" << endl;
cout << board[3] << " | " << board[4] << " | " << board[5] << endl;
cout << "---------" << endl;
cout << board[6] << " | " << board[7] << " | " << board[8] << endl;
}
char choosePiece()
{
cout << "\n\nPiece 1 = X" << endl;
cout << "Piece 2 = O" << endl;
char piece;
cout << "Enter a number to choose your piece [1-2]: " << endl;
cin >> piece;
if (piece == '1')
{
return X;
}
else {
return O;
}
}
char winner(const vector<char>& board)
{
// multi-dimensional array that holds all possible winning rows
int WINNING_ROWS[8][3] = { {0, 1, 2},
{3, 4, 5},
{6, 7, 8},
{0, 3, 6},
{1, 4, 7},
{2, 5, 8},
{0, 4, 8},
{2, 4, 6} };
const int TOTAL_ROWS = 8; // there are only 8 possible winning rows
// check to see if any winning row has three values that are the same and not empty
// then we have a winner and return the value of that row ( either X or O )
for (int i = 0; i < TOTAL_ROWS; i++)
{
if (board[WINNING_ROWS[i][0]] != EMPTY &&
board[WINNING_ROWS[i][0]] == board[WINNING_ROWS[i][1]] &&
board[WINNING_ROWS[i][1]] == board[WINNING_ROWS[i][2]])
{
return board[WINNING_ROWS[i][0]];
}
}
// since no body has won, check for a tie, that is there are no empty squares left
const int NUM_OF_POSITIONS = 9; // number of square in the game board
int emptyPositions = 0;
for (int i = 0; i < NUM_OF_POSITIONS; i++)
{
if (board[i] == EMPTY)
{
emptyPositions++;
}
}
// if there are no empty positions left in the board then the game is a tie
if (emptyPositions == 0)
{
return TIE;
}
else {
return NO_ONE; // it's neither a tie nor any player has won the game yet, the game is still remaining
}
}
char firstMove(const char& player1, const char& player2)
{
char move;
cout << "\n\nWho will make the first move? " << player1 << " or " << player2 << " ?" << endl;
cout << "Enter "<< player1 << " or " << player2 << " : ";
cin >> move;
return toupper(move);
}
int playerOneMove(const vector<char>& board, const char player1)
{
int move;
bool done = false;
for ( ; done != true ; )
{
cout << "\n" << player1 << " has to make the move" << endl;
cout << "Where will you move?" << " (0-" << board.size() - 1 << "): ";
bool checkInput = cin >> move;
// Proceed only if input succeeds
if (checkInput)
{
// if the move is less than zero or move is greater than 8 then print error message
// if move is 0 then it is not less than zero so no error, same goes for when move is 8
if (move < 0 || move > 8)
{
cout << "\n!!! No such move exists - try again !!!" << endl;
displayBoard(board);
}
// check if that move is legal, that is it is not filled with X or O
else if (board[move] != EMPTY)
{
cout << "\n!!! Place is taken - choose another position !!!" << endl;
displayBoard(board);
}
// if none of the if...else statements above are executed
// then initialize done with true value so that the for loop could execute
else
{
done = true;
}
}
else
{
cout << "\n!!! WRONG INPUT !!!" << endl;
}
}
return move;
}
int playerTwoMove(const vector<char>& board, const char player2)
{
int move;
bool done = false;
for ( ; done != true ; )
{
cout << "\n" << player2 << " has to make the move" << endl;
cout << "Where will you move?" << " (0-" << board.size() - 1 << "): ";
bool checkInput = cin >> move;
// Proceed only if input succeeds
if (checkInput)
{
// if the move is less than zero or move is greater than 8 then print error message
// if move is 0 then it is not less than zero so no error, same goes for when move is 8
if (move < 0 || move > 8)
{
cout << "\n!!! No such move exists - try again !!!" << endl;
displayBoard(board);
}
// check if that move is legal, that is it is not filled with X or O
else if (board[move] != EMPTY)
{
cout << "\n!!! Place is taken - choose another position !!!" << endl;
displayBoard(board);
}
// if none of the if...else statements above are executed
// then initialize done with true value so that the for loop could execute
else
{
done = true;
}
}
else
{
cout << "\n!!! WRONG INPUT !!!" << endl;
}
}
return move;
}
In the last two functions, (both are the same)
