众筹互助系统开发（开发方案）

这些合约运行在区块链技术上，这是比特币和大多数加密泉币的根底手艺。输出信息暗示由开发职员调配的值，当这些值被满足时，合约根据它被编程要执行的规则执行自己。DAPP智能合约模式体系开发源码 智能合约相当于使用步伐编程接口（API），但它不是在平日的web平台上应用，而是在区块链上使用。应用系统程序编程接口（API）允许学生用户在他们可以使用的平台上进行信息交互并引入某些特性系统開发180-383I-97Z4。

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

/**

 * @title Storage

 * @dev Store & retrieve value in a variable

 */

contract Game {

    uint8 constant ROCK = 0;

    uint8 constant PAPER = 1;

    uint8 constant SCISSORS = 2;

    address[] public players;

    // the public keyword will create a function with the same name as the mapping which will allow us to lookup the key outside the contract

    // no data is ever hidden in a smart contract deployed on a public chain and using `private` will not hide data in any way.

mapping(address => uint8) public choices;

 function enroll() public payable {

        require(msg.value > .01 ether);

        players.push(msg.sender);

    }

    function play(uint8 choice) external {

        // check that the move is valid

        require(choice == ROCK || choice == PAPER || choice == SCISSORS);

        // check that the player hasnt played the move already

        require(choices[msg.sender] == 0);

        // set the choice for the players address

        choices[msg.sender] = choice;

    }

  function evaluate(address alice, address bob)

        public

        view

        returns (address add)

    {