Simple Tic-Tac-Toe Game in C++

Introduction

Tic-Tac-Toe is a classic game that is widely recognized and played by people of all ages. The game is usually played by two players, one using ‘X’ and the other using ‘O’. The goal is to place three of the player’s marks in a horizontal, vertical, or diagonal row on a 3×3 grid.

This program is a simple console-based implementation of the Tic-Tac-Toe game in C++. The program will allow two players to take turns and place their marks (‘X’ or ‘O’) on the grid until one player wins or the game ends in a draw.

Objective

The objective of this program is to create a functional, interactive Tic-Tac-Toe game where two players can take turns, the board is updated after each move, and the game will declare a winner or a draw at the end. The code should be simple enough for beginners to understand the logic behind the game and the basic structure of a C++ program.

Code

#include 
using namespace std;

char board[3][3] = {{'1', '2', '3'}, {'4', '5', '6'}, {'7', '8', '9'}}; // Tic-Tac-Toe board
int choice; // User's choice for position to place mark
int row, column; // Row and column to place mark
char turn = 'X'; // Starting player is 'X'
bool draw = false; // Condition to check if the game is a draw

// Function to display the board
void display_board() {
    cout << "\n\nTic-Tac-Toe Board\n";
    cout << "Player 1 [X] - Player 2 [O]\n\n";
    cout << "     |     |     \n";
    cout << "  " << board[0][0] << "  |  " << board[0][1] << "  |  " << board[0][2] << " \n";
    cout << "_____|_____|_____\n";
    cout << "     |     |     \n";
    cout << "  " << board[1][0] << "  |  " << board[1][1] << "  |  " << board[1][2] << " \n";
    cout << "_____|_____|_____\n";
    cout << "     |     |     \n";
    cout << "  " << board[2][0] << "  |  " << board[2][1] << "  |  " << board[2][2] << " \n";
    cout << "     |     |     \n";
}

// Function to take player's input and update the board
void player_turn() {
    cout << "Player " << turn << ", enter the number (1-9) where you want to place your mark: "; cin >> choice;

    // Determine the row and column from the player's input
    row = (choice - 1) / 3;
    column = (choice - 1) % 3;

    // If the position is already taken, ask the player to choose another spot
    if (board[row][column] != 'X' && board[row][column] != 'O') {
        board[row][column] = turn; // Place the player's mark
    } else {
        cout << "Position already taken. Try again.\n";
        player_turn(); // Recurse until a valid move is made
    }
}

// Function to check the winning condition
bool game_won() {
    // Check for horizontal, vertical, and diagonal wins
    for (int i = 0; i < 3; i++) {
        if (board[i][0] == board[i][1] && board[i][1] == board[i][2]) {
            return true;
        }
        if (board[0][i] == board[1][i] && board[1][i] == board[2][i]) {
            return true;
        }
    }
    if (board[0][0] == board[1][1] && board[1][1] == board[2][2]) {
        return true;
    }
    if (board[0][2] == board[1][1] && board[1][1] == board[2][0]) {
        return true;
    }
    return false;
}

// Function to check for a draw
bool game_draw() {
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            if (board[i][j] != 'X' && board[i][j] != 'O') {
                return false;
            }
        }
    }
    return true;
}

// Main game loop
int main() {
    cout << "Welcome to Tic-Tac-Toe Game!\n";
    display_board();

    while (true) {
        player_turn();
        display_board();

        // Check if the current player has won
        if (game_won()) {
            cout << "Player " << turn << " wins the game!\n";
            break;
        }

        // Check if the game is a draw
        if (game_draw()) {
            cout << "It's a draw!\n";
            break;
        }

        // Switch turns
        turn = (turn == 'X') ? 'O' : 'X';
    }

    return 0;
}

Program Explanation

The program begins by initializing a 3×3 board using a 2D array where each position is initially filled with numbers 1-9. This allows the player to see the available positions before making their move.

The display_board() function is used to display the current state of the Tic-Tac-Toe board to the players. The game board is printed with each player’s mark and the remaining available positions.

The player_turn() function allows players to input their chosen position (1-9). The program checks if the position is already taken, and if so, prompts the player to select another one. Once a valid move is made, the board is updated with the player’s mark.

The game_won() function checks whether there is a winner by checking for three consecutive marks horizontally, vertically, or diagonally. The game_draw() function checks if all positions on the board are filled, indicating a draw.

The game continues until one of the players wins or the game ends in a draw. After each turn, the game alternates between Player ‘X’ and Player ‘O’.

How to Run the Program

To run the Tic-Tac-Toe game:

• • Save the code in a file with a .cpp extension (e.g., tictactoe.cpp).
  • Open a terminal or command prompt and navigate to the directory where the file is saved.
  • Compile the program using a C++ compiler. For example, if you are using g++, run the following command:

g++ tictactoe.cpp -o tictactoe

• • Run the compiled program:

./tictactoe

• Follow the on-screen prompts to play the game!