Tic Tac Toe in C

A simple command-line Tic Tac Toe game written in C. Play against a friend or against the computer.

Features

• Two modes: Player vs Player and Player vs Computer
• Computer opponent that wins when it can, blocks your winning move, and prefers the centre and corners
• Input validation (rejects letters, out-of-range numbers and already-taken cells)
• Score tracking across multiple rounds (X wins, O wins, draws)
• Custom player names
• Play again without restarting the program

Requirements

• A C compiler such as gcc or clang
• Works on Linux, macOS and Windows (MinGW / WSL)

Build and Run

gcc tictactoe.c -o tictactoe
./tictactoe

On Windows (MinGW):

gcc tictactoe.c -o tictactoe.exe
tictactoe.exe

How to Play

The board cells are numbered 1 to 9:

     1 | 2 | 3
    ---+---+---
     4 | 5 | 6
    ---+---+---
     7 | 8 | 9

1. Choose a mode (1 = two players, 2 = vs computer).
2. Enter player name(s).
3. On your turn, type the number of the cell where you want to place your mark and press Enter.
4. Get three marks in a row (horizontal, vertical or diagonal) to win.
5. If all nine cells fill up with no winner, the game is a draw.
6. After each round, enter y to play again or n to quit.

Sample Output

=====================================
         TIC  TAC  TOE  (C)
=====================================
  1. Player vs Player
  2. Player vs Computer
Select mode (1 or 2): 2
Enter name for X: Deval

     1 | 2 | 3
    ---+---+---
     4 | 5 | 6
    ---+---+---
     7 | 8 | 9

Deval (X), choose a cell (1-9): 5

Project Structure

tictactoe/
├── tictactoe.c   # Game source code
└── README.md     # This file

How the Code Works

Function	Purpose
resetBoard()	Fills the board with the numbers 1-9
printBoard()	Draws the current board
checkWinner()	Checks rows, columns and both diagonals
isDraw()	Returns true when no free cells remain
getHumanMove()	Reads and validates a move from the player
getComputerMove()	Picks a move: win, block, centre, corner, then random
playGame()	Runs one full round and returns the result

Possible Improvements

• Unbeatable computer using the Minimax algorithm
• Larger boards (4x4, 5x5)
• Colored output using ANSI escape codes

License

Free to use and modify for learning purposes.