我正在创建这个智能合约,它会创建所有代币并将其添加到我的钱包中。 然后我将钱包中的所有代币发送到我的合约中。
但是,当我从另一个钱包向合约发送 BNB 时,我希望他返回我合约中的一些代币。
当我这样做时,传输失败并发送以下错误消息:
警告!合约执行过程中遇到错误[out ofgas]
Queria saber se estou fazendo algo errado, ou como devo fazer para que meu contrato tenha gas。
交易详情:https://testnet.bscscan.com/tx/0x7ef36e49e3c6f77716aee79cefbde6c298c3ddeef16ed12dbe613573661135bb
智能合约:
pragma solidity ^0.8.0; interface IERC20 { function totalSupply() external view returns (uint256); function balanceOf(address account) external view returns (uint256); function allowance(address owner, address spender) external view returns (uint256); function transfer(address recipient, uint256 amount) external returns (bool); function approve(address spender, uint256 amount) external returns (bool); function transferFrom(address sender, address recipient, uint256 amount) external returns (bool); event Transfer(address indexed from, address indexed to, uint256 value); event Approval(address indexed owner, address indexed spender, uint256 value); } contract ERC20Basic is IERC20 { string public constant name = "ByeSeel"; string public constant symbol = "BYS"; uint8 public constant decimals = 18; event Approval(address indexed tokenOwner, address indexed spender, uint tokens); event Transfer(address indexed from, address indexed to, uint tokens); mapping(address => uint256) balances; mapping(address => mapping (address => uint256)) allowed; uint256 totalSupply_ = 100 * 10 ** 18; using SafeMath for uint256; constructor() public { balances[msg.sender] = totalSupply_; } function totalSupply() public override view returns (uint256) { return totalSupply_; } function balanceOf(address tokenOwner) public override view returns (uint256) { return balances[tokenOwner]; } function transfer(address receiver, uint256 numTokens) public override returns (bool) { require(numTokens <= balances[msg.sender]); balances[msg.sender] = balances[msg.sender].sub(numTokens); balances[receiver] = balances[receiver].add(numTokens); emit Transfer(msg.sender, receiver, numTokens); return true; } function approve(address delegate, uint256 numTokens) public override returns (bool) { allowed[msg.sender][delegate] = numTokens; emit Approval(msg.sender, delegate, numTokens); return true; } function allowance(address owner, address delegate) public override view returns (uint) { return allowed[owner][delegate]; } function transferFrom(address owner, address buyer, uint256 numTokens) public override returns (bool) { require(numTokens <= balances[owner]); require(numTokens <= allowed[owner][msg.sender]); balances[owner] = balances[owner].sub(numTokens); allowed[owner][msg.sender] = allowed[owner][msg.sender].sub(numTokens); balances[buyer] = balances[buyer].add(numTokens); emit Transfer(owner, buyer, numTokens); return true; } event Received(address, uint); receive() external payable { emit Received(msg.sender, msg.value); } } library SafeMath { function sub(uint256 a, uint256 b) internal pure returns (uint256) { assert(b <= a); return a - b; } function add(uint256 a, uint256 b) internal pure returns (uint256) { uint256 c = a + b; assert(c >= a); return c; } } contract DEX { event Bought(uint256 amount); event Sold(uint256 amount); IERC20 public token; constructor() public { token = new ERC20Basic(); } function buy() payable public { uint256 amountTobuy = msg.value; uint256 dexBalance = token.balanceOf(address(this)); require(amountTobuy > 0, "You need to send some Ether"); require(amountTobuy <= dexBalance, "Not enough tokens in the reserve"); token.transfer(msg.sender, amountTobuy); emit Bought(amountTobuy); } function sell(uint256 amount) public { require(amount > 0, "You need to sell at least some tokens"); uint256 allowance = token.allowance(msg.sender, address(this)); require(allowance >= amount, "Check the token allowance"); token.transferFrom(msg.sender, address(this), amount); msg.sender.transfer(amount); emit Sold(amount); } }
最佳答案
根据 BscScan 上的交易详细信息,您正在尝试发送 0.1 BNB 并且未调用任何函数。
您的契约(Contract)没有 receive() ,也不是 fallback()函数,它将接受传入的 BNB。
因此您需要做的就是实现 receive()
函数。请注意允许此函数接受 BNB 的 payable
修饰符。
contract ERC20Basic is IERC20 {
// rest of your code
receive() external payable {
// can call the buy() function
buy();
}
}
您可以在 screenshot 中看到当您向合约发送 100 wei(如果是 BNB 则为 100 jager)时,receive()
函数会执行 buy()
函数并生成 购买了
事件日志。
这是在您的合约上实现的完整代码:
pragma solidity ^0.8.0;
interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function transfer(address recipient, uint256 amount) external returns (bool);
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
contract ERC20Basic is IERC20 {
string public constant name = "ByeSeel";
string public constant symbol = "BYS";
uint8 public constant decimals = 18;
//event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
//event Transfer(address indexed from, address indexed to, uint tokens);
mapping(address => uint256) balances;
mapping(address => mapping (address => uint256)) allowed;
uint256 totalSupply_ = 100 * 10 ** 18;
using SafeMath for uint256;
constructor() public {
balances[msg.sender] = totalSupply_;
}
function totalSupply() public override view returns (uint256) {
return totalSupply_;
}
function balanceOf(address tokenOwner) public override view returns (uint256) {
return balances[tokenOwner];
}
function transfer(address receiver, uint256 numTokens) public override returns (bool) {
require(numTokens <= balances[msg.sender]);
balances[msg.sender] = balances[msg.sender].sub(numTokens);
balances[receiver] = balances[receiver].add(numTokens);
emit Transfer(msg.sender, receiver, numTokens);
return true;
}
function approve(address delegate, uint256 numTokens) public override returns (bool) {
allowed[msg.sender][delegate] = numTokens;
emit Approval(msg.sender, delegate, numTokens);
return true;
}
function allowance(address owner, address delegate) public override view returns (uint) {
return allowed[owner][delegate];
}
function transferFrom(address owner, address buyer, uint256 numTokens) public override returns (bool) {
require(numTokens <= balances[owner]);
require(numTokens <= allowed[owner][msg.sender]);
balances[owner] = balances[owner].sub(numTokens);
allowed[owner][msg.sender] = allowed[owner][msg.sender].sub(numTokens);
balances[buyer] = balances[buyer].add(numTokens);
emit Transfer(owner, buyer, numTokens);
return true;
}
event Received(address, uint);
receive() external payable {
emit Received(msg.sender, msg.value);
}
}
library SafeMath {
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
assert(b <= a);
return a - b;
}
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
assert(c >= a);
return c;
} }
contract DEX {
event Bought(uint256 amount);
event Sold(uint256 amount);
IERC20 public token;
constructor() public {
token = new ERC20Basic();
}
function buy() payable public {
uint256 amountTobuy = msg.value;
uint256 dexBalance = token.balanceOf(address(this));
require(amountTobuy > 0, "You need to send some Ether");
require(amountTobuy <= dexBalance, "Not enough tokens in the reserve");
token.transfer(msg.sender, amountTobuy);
emit Bought(amountTobuy);
}
function sell(uint256 amount) public {
require(amount > 0, "You need to sell at least some tokens");
uint256 allowance = token.allowance(msg.sender, address(this));
require(allowance >= amount, "Check the token allowance");
token.transferFrom(msg.sender, address(this), amount);
payable(msg.sender).transfer(amount);
emit Sold(amount);
}
receive() external payable {
buy();
}
}
关于blockchain - 使用 BNB 从合约购买代币时出现问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/67435585/