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面向 Solidity 智能合约的OOP编程语言






下面是一个很简单的''Hello, World!"智能合约代码。

// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.9.0;

contract HelloWorld {
    function helloWorld() external pure returns (string memory) {
        return "Hello, World!";

要开始使用Solidity,您可以使用基于浏览器的IDE Remix。以下是一些合同示例:

  • 投票

    // SPDX-License-Identifier: GPL-3.0
    pragma solidity >=0.7.0 <0.9.0;
    /// @title Voting with delegation.
    contract Ballot {
    // This declares a new complex type which will
    // be used for variables later.
    // It will represent a single voter.
    struct Voter {
        uint weight; // weight is accumulated by delegation
        bool voted;  // if true, that person already voted
        address delegate; // person delegated to
        uint vote;   // index of the voted proposal
    // This is a type for a single proposal.
    struct Proposal {
        bytes32 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;
    /// Create a new ballot to choose one of `proposalNames`.
    constructor(bytes32[] memory proposalNames) {
        chairperson = msg.sender;
        voters[chairperson].weight = 1;
        // For each of the provided proposal names,
        // create a new proposal object and add it
        // to the end of the 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`.
                name: proposalNames[i],
                voteCount: 0
    // Give `voter` the right to vote on this ballot.
    // May only be called by `chairperson`.
    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.
            msg.sender == chairperson,
            "Only chairperson can give right to vote."
            "The voter already voted."
        require(voters[voter].weight == 0);
        voters[voter].weight = 1;
    /// Delegate your vote to the 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[].voteCount += sender.weight;
        } else {
            // If the delegate did not vote yet,
            // add to her weight.
            delegate_.weight += sender.weight;
    /// Give your vote (including votes delegated to you)
    /// to proposal `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; = 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 (bytes32 winnerName_)
        winnerName_ = proposals[winningProposal()].name;
  • 盲拍

    // SPDX-License-Identifier: GPL-3.0
    pragma solidity ^0.8.4;
    contract SimpleAuction {
    // Parameters of the auction. Times are either
    // absolute unix timestamps (seconds since 1970-01-01)
    // or time periods in seconds.
    address payable public beneficiary;
    uint public auctionEndTime;
    // Current state of the auction.
    address public highestBidder;
    uint public highestBid;
    // Allowed withdrawals of previous bids
    mapping(address => uint) pendingReturns;
    // Set to true at the end, disallows any change.
    // By default initialized to `false`.
    bool ended;
    // Events that will be emitted on changes.
    event HighestBidIncreased(address bidder, uint amount);
    event AuctionEnded(address winner, uint amount);
    // Errors that describe failures.
    // The triple-slash comments are so-called natspec
    // comments. They will be shown when the user
    // is asked to confirm a transaction or
    // when an error is displayed.
    /// The auction has already ended.
    error AuctionAlreadyEnded();
    /// There is already a higher or equal bid.
    error BidNotHighEnough(uint highestBid);
    /// The auction has not ended yet.
    error AuctionNotYetEnded();
    /// The function auctionEnd has already been called.
    error AuctionEndAlreadyCalled();
    /// Create a simple auction with `biddingTime`
    /// seconds bidding time on behalf of the
    /// beneficiary address `beneficiaryAddress`.
        uint biddingTime,
        address payable beneficiaryAddress
    ) {
        beneficiary = beneficiaryAddress;
        auctionEndTime = block.timestamp + biddingTime;
    /// Bid on the auction with the value sent
    /// together with this transaction.
    /// The value will only be refunded if the
    /// auction is not won.
    function bid() external payable {
        // No arguments are necessary, all
        // information is already part of
        // the transaction. The keyword payable
        // is required for the function to
        // be able to receive Ether.
        // Revert the call if the bidding
        // period is over.
        if (block.timestamp > auctionEndTime)
            revert AuctionAlreadyEnded();
        // If the bid is not higher, send the
        // money back (the revert statement
        // will revert all changes in this
        // function execution including
        // it having received the money).
        if (msg.value <= highestBid)
            revert BidNotHighEnough(highestBid);
        if (highestBid != 0) {
            // Sending back the money by simply using
            // highestBidder.send(highestBid) is a security risk
            // because it could execute an untrusted contract.
            // It is always safer to let the recipients
            // withdraw their money themselves.
            pendingReturns[highestBidder] += highestBid;
        highestBidder = msg.sender;
        highestBid = msg.value;
        emit HighestBidIncreased(msg.sender, msg.value);
    /// Withdraw a bid that was overbid.
    function withdraw() external returns (bool) {
        uint amount = pendingReturns[msg.sender];
        if (amount > 0) {
            // It is important to set this to zero because the recipient
            // can call this function again as part of the receiving call
            // before `send` returns.
            pendingReturns[msg.sender] = 0;
            if (!payable(msg.sender).send(amount)) {
                // No need to call throw here, just reset the amount owing
                pendingReturns[msg.sender] = amount;
                return false;
        return true;
    /// End the auction and send the highest bid
    /// to the beneficiary.
    function auctionEnd() external {
        // It is a good guideline to structure functions that interact
        // with other contracts (i.e. they call functions or send Ether)
        // into three phases:
        // 1. checking conditions
        // 2. performing actions (potentially changing conditions)
        // 3. interacting with other contracts
        // If these phases are mixed up, the other contract could call
        // back into the current contract and modify the state or cause
        // effects (ether payout) to be performed multiple times.
        // If functions called internally include interaction with external
        // contracts, they also have to be considered interaction with
        // external contracts.
        // 1. Conditions
        if (block.timestamp < auctionEndTime)
            revert AuctionNotYetEnded();
        if (ended)
            revert AuctionEndAlreadyCalled();
        // 2. Effects
        ended = true;
        emit AuctionEnded(highestBidder, highestBid);
        // 3. Interaction


Solidity文档托管在Read the docs上。

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