Tic Tac Toe GPN

Use this code to create your very own tic tac toe game to play with friends!

I did this project at my fifth Girls Programming Network (GPN) where I got to meet new friends and also run into some familiar faces. It was fun as always to hang out the entire day just coding and having fun.

I used EdStem to write and run my code.

# Created by Ahla, Anas 16/07/2025
# v1.1 Multiple gameplay implemented
# v1.0 Board cleaned up; commented the code; f string used; cleaned up inputs and logic
# v0.9 Initial release

# Declare an empty array of 9 elements
board = [" "," "," "," "," "," "," "," "," "]
game_continue=""

# Function to draw the canvas on screen
def print_board(board):
    print(" ")
    print(" ", board[0], "|", board[1], "|", board[2], " ")
    print("-------------")
    print(" ", board[3], "|", board[4], "|", board[5], " ")
    print("-------------")
    print(" ", board[6], "|", board[7], "|", board[8], " ")
    print(" ")

# Define winning logic
def check_winner(board):
    # First row is filled with the same symbol (O or X), so game over!
    if board[0] == board[1] == board[2] != " ":
        return True
    # Second row is filled with the same symbol (O or X), so game over!
    elif board[3] == board[4] == board[5] != " ":
        return True
    # Third row is filled with the same symbol (O or X), so game over!
    elif board[6] == board[7] == board[8] != " ":
        return True
    # First column is filled with the same symbol (O or X), so game over!
    if board[0] == board[3] == board[6] != " ":
        return True
    # Second column is filled with the same symbol (O or X), so game over!
    elif board[1] == board[4] == board[7] != " ":
        return True
    # Third column is filled with the same symbol (O or X), so game over!
    elif board[2] == board[5] == board[8] != " ":
        return True
    # Diagonal (left to right) is filled with the same symbol (O or X), so game over!
    if board[0] == board[4] == board[8] != " ":
        return True
    # Diagonal (right to left) is filled with the same symbol (O or X), so game over!
    elif board[2] == board[4] == board[6] != " ":
        return True
    # No one has won so far, continue the game
    else:
        return False
    
# Gameplay begins
# Welcome message and get player names
print("Welcome to Tic-Tac-Toe")
player_O = input("Who is playing naughts [O]? ")
player_X = input("Who is playing crosses [X]? ")
print(f"Welcome {player_O}, your symbol is O")
print(f"Welcome {player_X}, your symbol is X")
    
# Define Game loop
def game_loop():
    # Define variables
    game_over = False
    symbol = "O"
    current_player = player_O
    # Declare an empty array of 9 elements
    board = [" "," "," "," "," "," "," "," "," "]

    # Draw the canvas on screen
    print_board(board)
    
    # Game loop
    while game_over == False:
        # Info about the current player
        print(f"The current player is {current_player} playing {symbol}")

        # Take input from the player with validation
        while True:
            try:
                square_input = input("Which square do you want to place your symbol in (1 to 9)? ")
                # Since our board array has 9 elements from 0 to 8, "1" is subtracted from the input
                square_index = int(square_input)-1
                
                # Check if input is within valid range of 0 to 8 (for the user: 1 to 9)
                if square_index < 0 or square_index > 8:
                    print("Invalid input. Please enter a number between 1 and 9.")
                # Check if square is already occupied
                elif board[square_index] != " ":
                    print("That square is already occupied. Please choose another.")
                else:
                    break  # Input is valid, exit the validation loop
                    
            # Input might be string
            except ValueError:
                print("Invalid input. Please enter a number between 1 and 9.")


        # Assign the player's symbol to the board array
        board[square_index] = symbol

        print_board(board)
        game_over = check_winner(board)
        
        if game_over == True:
            print("=======================")
            print(f"{current_player} [{symbol}] won! Congratulations!")
            print("=======================")
            break  # Exit the game loop if there's a winner
            
        # Check for a tie (board is full)
        # No space on the board
        if " " not in board:
            print("=======================")
            print("It's a tie!")
            print("=======================")
            # Let's exit the game
            game_over = True
            break
        
    ##    # Alternate logic
    ##    # Take the count of spaces on the board. If no space, let's exit the game
    ##    if board.count(" ") == 0:
    ##        print("It's a tie!")
    ##        game_over = True
    ##        break
            
        # Change the current player and symbol to the next
        if symbol == "O":
            current_player = player_X
            symbol = "X"
        else:
            current_player = player_O
            symbol = "O"

# Game loop
game_loop()

# Ask to play again
# Infinite loop
while True:
    # Get input to the variable and strip any spaces before valid input
    game_continue = input("\nWould you like to play one more game? Yes [Y] or No [N]: ").strip()
    # Captures input and looks for yes "Y"
    if game_continue and game_continue[0].upper() == "Y":
        game_loop()
    # Exits the game if any other input comes
    else:
        print("=======================")
        print("GAME OVER!")
        print("=======================")
        # Exit the infinite while loop
        break

I would like to also like to implement a computer vs user version of tic tac toe in the future. I think it will also be fun to make the game graphical with a board in which players can play. This will make it more interactive and hands on to play.

Look forward to that blog coming soon!