猜數字範例

GuessNumber.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.8.2 <0.9.0;

/**
 * @title Storage
 * @dev Store & retrieve value in a variable
 * @custom:dev-run-script ./scripts/deploy_with_ethers.ts
 */
contract GuessNumber {

    uint256 totalParticipants = 500;
    uint256 maxNum = 200;
    uint256 minNum = 1;

    uint256 number;
    uint256 answer;

    address owner;

    mapping(address => uint) public guessNumberMap;
    mapping(address => bool) public isVip;
    mapping(address => bool) public isParticipate;

    address[] vipList;

    constructor(address[] memory whitelist ) {
        owner = msg.sender;

        for(uint256 i =0; i < whitelist.length; i++){
            
            address user = whitelist[i];
            vipList.push(whitelist[i]);
            isVip[user] = true;
        }
    }

    function guessNumber(uint256 _guessNum) public {
        require(isVip[msg.sender] == true, "Not a VIP.");
        require(isParticipate[msg.sender] ==false, "already answer.");
        require(_guessNum <= maxNum && _guessNum >= minNum, "over range.");
        guessNumberMap[msg.sender] = _guessNum;
        isParticipate[msg.sender] = true;
    }

    function setAnswer(uint256 _answer) public {
        require(owner == msg.sender, "not an owner!");
        require(_answer <= maxNum && _answer >= minNum, "over range.");
        answer = _answer;
    }

    function getRewards() public {
        require(owner == msg.sender, "not an owner!");
        //1. 取得答案 - answer
        //2. 知道每個人選了什麼數字
        for (uint i = 0; i < vipList.length; i++) {
            address user = vipList[i];
            uint256 num = guessNumberMap[user]; 
            if (num == answer){ //3. 判斷誰對中了數字
                //4. 發幣 - 0.1 ETH
                payable(user).transfer(10**17);
            }
        }
    }

    function retrieve() public view returns (uint256){
        return number; 
    }

    function deposit() external payable {
    }
}