如何在彩票去中心化彩票應用中獲取中獎者的地址

Question

我在solidity中創建了一個彩票應用程序。 All things are working fine but I want to add this feature that when the winner is selected it should return me the address of winner as well.

我能為此做些什么？ 任何幫助將不勝感激，謝謝。 這是我的可靠代碼。

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;

contract Lottery_Application {

    address public manager;
    address payable[] public participants;

    constructor() {
        manager=msg.sender;
    }

    receive() external payable {
        require(msg.value>=1 ether);
        participants.push(payable(msg.sender));
    }

    function getbalance() public view returns(uint) {
        require(msg.sender==manager);
        return address(this).balance;

    }

    function random() public view returns(uint) {
        return uint(keccak256(abi.encodePacked(block.difficulty,block.timestamp,participants.length)));
    }

    function selectwinner() public returns(address) {
        require(msg.sender==manager);
        require(participants.length>=3);
        uint r=random();
        address payable winner;
        uint index=r% participants.length;
        winner=participants[index];
        winner.transfer(getbalance());
        winner=address(msg.sender);
        return winner;
    }
}

Answer 1

狀態改變函數不能返回任何東西。 你可以通過兩種方式做到這一點。

1. 創建和使用事件。

event WinnerSelected(address winner)

在您的獲勝者選擇函數結束時， emit WinnerSelected(winner) 。

2. 創建一個全局變量來存儲最近的獲勝者。 address public recentWinner

在您的獲勝者選擇函數的末尾， recentWinner = winner 。