使用solidity实现基本的投票并且去操作功能,像是投票,发票或是委托票等。
创建contract
Solidity by Example — Solidity 0.8.10 documentation (soliditylang.org)
// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
/// @title Voting with delegation.
contract Voting {
// 选民
struct Voter {
uint weight; // weight is accumulated by delegation
bool voted; // if true, that person already voted
address delegate; // 被委托人 person delegated to
uint vote; // 投票提案的索引 index of the voted proposal
}
// This is a type for a single proposal.
struct Proposal {
string name; // short name (up to 32 bytes)
uint voteCount; // number of accumulated votes
}
address public chairperson;
// This declares a state variable that
// stores a `Voter` struct for each possible address.
mapping(address => Voter) public voters;
// A dynamically-sized array of `Proposal` structs.
Proposal[] public proposals;
// 为`proposalNames` 中的每个提案,创建一个新投票表决 Create a new ballot to choose one of `proposalNames`.
constructor(string[] memory proposalNames) {
chairperson = msg.sender;
voters[chairperson].weight = 1;
// 对每一提案名称,创建一个新的Proposal并添加到array
for (uint i = 0; i < proposalNames.length; i++) {
// `Proposal({...})` creates a temporary
// Proposal object and `proposals.push(...)`
// appends it to the end of `proposals`.
proposals.push(Proposal({
name: proposalNames[i],
voteCount: 0
}));
}
}
// 授权voter对这个表决进行投票,只有chairperson能调用此函数
function giveRightToVote(address voter) external {
// If the first argument of `require` evaluates
// to `false`, execution terminates and all
// changes to the state and to Ether balances
// are reverted.
// This used to consume all gas in old EVM versions, but
// not anymore.
// It is often a good idea to use `require` to check if
// functions are called correctly.
// As a second argument, you can also provide an
// explanation about what went wrong.
require(
msg.sender == chairperson,
"Only chairperson can give right to vote."
);
require(
!voters[voter].voted,
"The voter already voted."
);
require(voters[voter].weight == 0);
voters[voter].weight = 1;
}
/// 将您的投票委托给选民 voter `to`.
function delegate(address to) external {
// assigns reference
Voter storage sender = voters[msg.sender];
require(!sender.voted, "You already voted.");
require(to != msg.sender, "Self-delegation is disallowed.");
// Forward the delegation as long as
// `to` also delegated.
// In general, such loops are very dangerous,
// because if they run too long, they might
// need more gas than is available in a block.
// In this case, the delegation will not be executed,
// but in other situations, such loops might
// cause a contract to get "stuck" completely.
while (voters[to].delegate != address(0)) {
to = voters[to].delegate;
// We found a loop in the delegation, not allowed.
require(to != msg.sender, "Found loop in delegation.");
}
// Since `sender` is a reference, this modifies `voters[msg.sender].voted`
sender.voted = true;
sender.delegate = to;
Voter storage delegate_ = voters[to];
if (delegate_.voted) {
// If the delegate already voted,
// directly add to the number of votes
proposals[delegate_.vote].voteCount += sender.weight;
} else {
// If the delegate did not vote yet,
// add to her weight.
delegate_.weight += sender.weight;
}
}
/// 把你的票(包括委托给你的票),投给提案`proposals[proposal].name`.
function vote(uint proposal) external {
Voter storage sender = voters[msg.sender];
require(sender.weight != 0, "Has no right to vote");
require(!sender.voted, "Already voted.");
sender.voted = true;
sender.vote = proposal;
// If `proposal` is out of the range of the array,
// this will throw automatically and revert all
// changes.
proposals[proposal].voteCount += sender.weight;
}
/// @dev Computes the winning proposal taking all
/// previous votes into account.
function winningProposal() public view
returns (uint winningProposal_)
{
uint winningVoteCount = 0;
for (uint p = 0; p < proposals.length; p++) {
if (proposals[p].voteCount > winningVoteCount) {
winningVoteCount = proposals[p].voteCount;
winningProposal_ = p;
}
}
}
// Calls winningProposal() function to get the index
// of the winner contained in the proposals array and then
// returns the name of the winner
function winnerName() external view
returns (string memory winnerName_)
{
winnerName_ = proposals[winningProposal()].name;
}
}
启动节点模拟
使用Remix
Compile
Deploy合约
Output:
测试Proposals
结果
chairperson
chairperson(0xac55502aF00E1F405f115C17F45D43c36C47F7C3)给其他人票:
其他也是:
0xF197FFB0422d7026809210826325bfa719105251
0x7CB7374abE10dDd7e16b3dfe5E68623DAb1b13F3
0x9AD3eB9367f6B123a843AcF946e4D360c445FB9d
测试非Chairperson给其他人票:
出现ERROR:
Output
测试Voter:
接着切换帐户:
0xF197FFB0422d7026809210826325bfa719105251
将自己的票委托给他人(0x7CB7374abE10dDd7e16b3dfe5E68623DAb1b13F3):
使用看Voter函数来观察:
测试投票:
0xF197FFB0422d7026809210826325bfa719105251
(我们把票给别人了,无法投,并且先看一下propsal)
能看到没有投成功
切换成其他人开始投票:
0x7CB7374abE10dDd7e16b3dfe5E68623DAb1b13F3
0x9AD3eB9367f6B123a843AcF946e4D360c445FB9d
执行vote
接着看proposal(Alice, Bob):
呼叫WINNERNAME和WINNINGPROPOSAL
合约内的东西都测试完毕
Reference:
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