The msg.sender Variable

msg.sender is a special global variable that contains the address of whoever called the function.

How it works:

When someone calls your contract function, Solidity automatically sets msg.sender to their address.

Example:

If address 0x123... calls your function, then msg.sender equals 0x123...

For our game, we'll use msg.sender to set playerX to whoever starts the game.

Write: playerX = msg.sender; and playerO = _opponent inside the startGame function.

Assign players using msg.sender

Requirements:

Assigns playerX to msg.sender

Assigns playerO to _opponent

// 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 {

    }
}