带有 transfer() 的支付修饰符答案

【问题标题】：payable modifier with transfer() in solidity带有 transfer() 的支付修饰符
【发布时间】：2022-09-27 16:21:43
【问题描述】：

我正在尝试在智能合约中使用存款和提取 ETH 代币。

contract A

function deposit() public payable{
  require(msg.value >= 0, \"Value amount to be deposit\");
  withdraw(msg.value);
}

function withdraw(uint256 _amount) internal{
   uint256 amount = 2 * _amount //modifying the amount(bonus or whatsoever)
   payable(msg.sender).transfer(amount);
}

上面的sn-p就是简单的表单充提功能。在这里存款工作正常，将帐户中的某些 ETH 存入合约地址。在执行结束时，它调用了withdraw，但传输函数仍然接受消息值作为参数，它似乎覆盖了数量参数。我已经在 remix ide 中验证了这些交易。

有人请帮我解决这个问题吗？

标签： ethereum solidity smartcontracts

【解决方案1】：

我使用 receive() 函数编辑了合约以接收 ETH。在安全帽脚本中，所有者将 100ETH 转移到合约中以模拟您的问题。编辑了合同，一切似乎都很好。

pragma solidity ^0.8.0;

import "hardhat/console.sol";

contract ContractA {
    event Received(address sender, uint value);

    receive() external payable {
        emit Received(msg.sender, msg.value);
    }

    function deposit() public payable{
        require(msg.value >= 0, "Value amount to be deposit");
        withdraw(msg.value);
    }

    function withdraw(uint256 _amount) internal{
        console.log(_amount);
        uint256 amount = 2 * _amount; //modifying the amount(bonus or whatsoever)
        console.log(amount);
        payable(msg.sender).transfer(amount);
    }
}

转移 100 ETH 并将 5ETH 存入合约的安全帽脚本：

import { ethers } from "hardhat";

const hre = require("hardhat");
async function main() {
  const [owner] = await hre.ethers.getSigners();

  const deposit = await ethers.getContractFactory("ContractA");
  const depositInstance = await deposit.deploy();
  await depositInstance.deployed();

  const depositContract = await hre.ethers.getContractFactory("ContractA");
  const instance = await depositContract.attach(`${depositInstance.address}`);

  const contractBalance = await hre.ethers.provider.getBalance(
    `${depositInstance.address}`
  );
  console.log("contract balance before tx", contractBalance.toString());

  await owner.sendTransaction({
    to: depositInstance.address,
    value: ethers.utils.parseUnits("100", 18),
  });
  const contractBalanceAfter = await hre.ethers.provider.getBalance(
    `${depositInstance.address}`
  );
  // Should be 100 ETH
  console.log("contract balance after tx", contractBalanceAfter.toString());

  // About 9899.99 ETH
  const ownerBalance = await hre.ethers.provider.getBalance(`${owner.address}`);
  console.log(
    `Owner balance before deposit ${ethers.utils.formatUnits(
      ownerBalance.toString(),
      18
    )}`
  );
  // After deposit balance should be 105 ETH
  await instance
    .connect(owner)
    .deposit({ value: ethers.utils.parseUnits("5", 18) });

  // After withdraw the balance should be 95ETH
  const contractBalanceAfterContract = await hre.ethers.provider.getBalance(
    `${depositInstance.address}`
  );
  console.log(
    "contract after contract interaction",
    contractBalanceAfterContract.toString()
  );

  // 9899.99 - 5 + 10 = 9904.99
  const ownerBalanceAfter = await hre.ethers.provider.getBalance(
    `${owner.address}`
  );
  console.log(
    `Owner balance before deposit ${ethers.utils.formatUnits(
      ownerBalanceAfter.toString(),
      18
    )}`
  );
}
main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

运行脚本显示它按预期工作

Compiled 1 Solidity file successfully
contract balance before tx 0
contract balance after tx 100000000000000000000
Owner balance before deposit 9899.999469435601476844
5000000000000000000
10000000000000000000
contract after contract interaction 95000000000000000000
Owner balance before deposit 9904.999416266040763879

【讨论】：

非常感谢您的快速帮助。真的很棒的工作！是的！我得到了最后一点，它将所有内容都转移给了用户。我需要将某些合同从合同发送到用户地址。您是否在合同中检查了足够的金额？就像一份合约持有 50 ETH，而您存入了两个调用的存款（存款 - 5 ETH 和提取 10 ETH）。即使合约有更多的余额，但提款仍然只转移 5 ETH。这就是这里的问题。
感谢您解决问题。我编辑了我的答案。