为令牌错误交换确切的令牌

如何解决为令牌错误交换确切的令牌

一段时间以来，我一直在尝试通过 uniswap 获得 Swap ExactTokenforToken 交换。不断提出问题。

我确实有一个成功部署的合约，但它一直收到传输错误。通过查看文档、帖子、此论坛等，我的理解是我没有转移/批准事件。

这是部署但不能交换的代码，供参考：

pragma solidity 0.7.1;

import "https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/interfaces/IUniswapV2Router02.sol";

contract UniswapExample {
  address internal constant UNISWAP_ROUTER_ADDRESS = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D ;

  IUniswapV2Router02 public uniswapRouter;
  address private multiDaiKovan = 0x4F96Fe3b7A6Cf9725f59d353F723c1bDb64CA6Aa;
  address private USDC = 0x2F375e94FC336Cdec2Dc0cCB5277FE59CBf1cAe5;
  
  constructor() {
    uniswapRouter = IUniswapV2Router02(UNISWAP_ROUTER_ADDRESS);
  }
  
  function convertUSDCtoEthtoDai(uint daiAmount,uint USDCAmount) public payable {
    uint deadline = block.timestamp + 15; // using 'now' for convenience,for mainnet pass deadline from frontend!
    uniswapRouter.swapExactTokensForTokens(USDCAmount,daiAmount,getPathForETHtoDAI(),address(this),deadline);
    // refund leftover ETH to user
    (bool success,) = msg.sender.call{ value: address(this).balance }("");
    require(success,"refund failed");

  }
  
  
  function getEstimatedETHforDAI(uint daiAmount) public view returns (uint[] memory) {
    return uniswapRouter.getAmountsIn(daiAmount,getPathForETHtoDAI());
  }

  function getPathForETHtoDAI() private view returns (address[] memory) {
    address[] memory path = new address[](3);
    path[0] = USDC;
    path[1] = uniswapRouter.WETH();
    path[2] = multiDaiKovan;
    
    return path;
  }
 
  
  // important to receive ETH
  receive() payable external {}
}

因此，我按照自己的方式编写了以下代码，但是，在“.transferFrom”上出现错误，提示“TypeError: Member “transferFrom” not found or not visible after argument-dependent lookup in address.

>

.approve 也发生了同样的情况。我已经为 Router02 和 IERC20 导入了 IERC20 接口。所以我无法部署合约来测试我是否接近。

这是新代码：

import "https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/interfaces/IUniswapV2Router02.sol";
import "https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/interfaces/IERC20.sol";

contract UniswapExample2 {

    address internal constant UNISWAP_ROUTER_ADDRESS = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D ;

    IUniswapV2Router02 public uniswapRouter;
    address private multiDaiKovan = 0x4F96Fe3b7A6Cf9725f59d353F723c1bDb64CA6Aa;
    address private USDC = 0x2F375e94FC336Cdec2Dc0cCB5277FE59CBf1cAe5;
  
    constructor() {
     uniswapRouter = IUniswapV2Router02(UNISWAP_ROUTER_ADDRESS);
  }
    function swapTokenForETH(uint amountIn,uint amountOutMin,uint deadline) public payable returns(uint[] memory) {
        // transfer
        require(USDC.transferFrom(msg.sender,amountIn),'transferFrom failed.');
        // approve
        require(USDC.approve(UNISWAP_ROUTER_ADDRESS,'approve failed.');
        // swap
        return uniswapRouter.swapExactTokensForTokens(amountIn,amountOutMin,msg.sender,deadline);
    }
    
    
    function getPathForETHtoDAI() private view returns (address[] memory) {
    address[] memory path = new address[](3);
    path[0] = USDC;
    path[1] = uniswapRouter.WETH();
    path[2] = multiDaiKovan;
    
    return path;
  }
}

我也尝试复制实际合约中的功能，但随后我收到错误消息，提示必须将整个合约标记为抽象。

任何建议/指导将不胜感激！

解决方法

您正在尝试对 transferFrom() 类型（未定义）执行 address 函数。

<address>.transferFrom()

它需要位于定义 transferFrom() 函数的接口上。​​

interface IERC20 {
    function transferFrom(address _from,address _to,uint256 _amount) external returns (bool);
}

contract UniswapExample2 {
    IERC20 private USDC = IERC20(0x2F375e94FC336Cdec2Dc0cCB5277FE59CBf1cAe5);

    function swapTokenForETH() public {
        USDC.transferFrom();
    }
}

注意：您已经（正确地）使用 IUniswapV2Router02 接口、uniswapRouter 属性和方法 swapExactTokensForTokens() 做同样的事情。 >