众筹智能合约编译报错：ParserError: Expected primary expression

错误原因及修复步骤 #

• 变量名不匹配
  合约中定义的贡献者数组为address [] public suppliers;，但在contribute和returnFunds函数里使用了未声明的backers变量，这是触发语法错误的核心原因。需将数组变量名统一：要么把suppliers改为backers，要么将函数内的backers替换为suppliers。

• 函数代码块未闭合
  returnFunds函数的for循环结束后，缺少闭合整个函数的大括号，导致编译器无法解析代码结构，引发语法错误。

• 可选优化（避免编译器警告）
  Solidity 0.8.x版本中now已被标记为过时，建议使用block.timestamp替代，功能完全一致但更符合当前规范。

修正后的完整代码 #

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.8;

contract Crowfunding {
    uint256 public fundingGoal; // 众筹目标金额
    uint256 public deadline; // 众筹截止时间
    uint256 public amountRaised; // 当前已筹集金额
    mapping (address => uint256) public contributions; // 记录每个地址的贡献金额
    address[] public backers; // 记录所有贡献者地址
    bool public funded;
    uint256 public fundsReturned;

    constructor(uint256 _fundingGoal, uint256 _deadline) {
        fundingGoal = _fundingGoal;
        deadline = _deadline;
    }

    function contribute() public payable {
        require(msg.value > 0, "You must contribute a positive amount.");
        require(block.timestamp <= deadline, "The deadline for contributions has passed.");

        contributions[msg.sender] += msg.value;
        amountRaised += msg.value;
        backers.push(msg.sender);
    }

    function returnFunds() public {
        require(block.timestamp > deadline, "The deadline for contributions has not passed yet.");
        require(fundsReturned == 0, "The funds have already been returned.");

        for (uint256 i = 0; i < backers.length; i++) {
            backers[i].transfer(contributions[backers[i]]);
        }
        fundsReturned = amountRaised; // 标记退款完成，防止重复执行
    }
}

内容的提问来源于stack exchange，提问作者Belen Paccioretti