W9day3.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.26;

contract CEI{
    mapping(address => uint256) private balances;

    function deposit() public payable {
        require(msg.value > 0, "Deposit something chat");//Check

        balances[msg.sender] += msg.value;//Effect
    }

    function withdraw(uint256 amount) public payable {
        require(balances[msg.sender] >= amount, "Insufficient fund");//Check

        balances[msg.sender] -= amount;//Effect
        //balances[msg.sender] -= amount;//uses msg.value instead of the amount parameter in the effect and interaction steps. This will cause incorrect balance updates and potential fund loss.

        (bool success,) = payable(msg.sender).call{value: amount}("");//Interaction
        require(success, "Transaction failed");
    }

    function getBalance() public view returns(uint256){
        return balances[msg.sender];
    }
}