Array Indexing

Arrays let you access individual elements using square brackets and an index number.

Syntax:

arrayName[index]

Important: Array indices start at 0, not 1!

Our board has 9 positions (0-8):

[0] [1] [2]
[3] [4] [5]
[6] [7] [8]

Remember that the default state of a Cell is Cell.Empty

To mark the center square as X:

board[4] = Cell.X;

Task: Try setting the center square (position 4) to Cell.X in a new public makeMove() function.

Create makeMove function

Requirements:

Creates public function makeMove

Has opening and closing braces

Sets board[4] to Cell.X

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract TicTacToe {
    address public playerX;
    address public playerO;

    enum Cell { Empty, X, O }

    Cell[9] public board;

    function startGame(address _opponent) public {
        playerX = msg.sender;
        playerO = _opponent;
    }

}