mkdir Voting
cd Voting
truffle unbox react-box

pragma solidity ^0.5.;

contract Voting {

  // a -> 10

  // b -> 5

  // c -> 20

  //["0x61","0x62","0x63"]

  mapping (bytes32 => uint8) public votesReceived;

  // 存储候选人名字的数组

  bytes32[] public candidateList;

  // 构造函数 初始化候选人名单

  constructor(bytes32[] memory candidateNames) public{

      candidateList = candidateNames;

  }

  // 查询某个候选人的总票数

  function totalVotesFor(bytes32 candidate) public view returns (uint8) {

    require(validCandidate(candidate) == true);

    // 或者

    // assert(validCandidate(candidate) == true);

    return votesReceived[candidate];

  }

  // 为某个候选人投票

  function voteForCandidate(bytes32 candidate) public {

    assert(validCandidate(candidate) == true);

    votesReceived[candidate] += ;

  }

  // 检索投票的姓名是不是候选人的名字

  function validCandidate(bytes32 candidate) public view returns (bool) {

    for(uint i = ; i < candidateList.length; i++) {

      if (candidateList[i] == candidate) {

        return true;

      }

    }

    return false;

  }

}