IDO代币预售智能合约系统开发技术搭建

IDO代币预售智能合约开发I762蕟O72搭9II9的Solidity编程代码示例及解释：

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pragma solidity ^0.8.0;

interface IERC20 {
  function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
  function balanceOf(address account) external view returns (uint256);
  function approve(address spender, uint256 amount) external returns (bool);
}

contract IDO {
  address public admin;
  IERC20 public token;
  uint256 public tokenPrice;
  uint256 public tokensSold;
  uint256 public minPurchase;
  uint256 public maxPurchase;
  mapping(address => uint256) public purchaseHistory;
 
  event TokensPurchased(address buyer, uint256 amount);

  constructor(address _admin, address _token, uint256 _tokenPrice, uint256 _minPurchase, uint256 _maxPurchase) {
    admin = _admin;
    token = IERC20(_token);
    tokenPrice = _tokenPrice;
    minPurchase = _minPurchase;
    maxPurchase = _maxPurchase;
  }

  function buyTokens(uint256 _amount) public payable {
    require(msg.value == _amount * tokenPrice, "Incorrect payment amount");
    require(token.balanceOf(address(this)) >= _amount, "Insufficient tokens available for purchase");
    require(_amount >= minPurchase && _amount <= maxPurchase, "Purchase amount must be within min/max limits");
   
    token.transferFrom(address(this), msg.sender, _amount);
    tokensSold += _amount;
    purchaseHistory[msg.sender] += _amount;
    emit TokensPurchased(msg.sender, _amount);
  }

  function withdrawTokens() public {
    require(msg.sender == admin, "Only the contract admin can withdraw tokens");
    uint256 balance = token.balanceOf(address(this));
    token.transfer(admin, balance);
  }
 
  function withdrawFunds() public {
    require(msg.sender == admin, "Only the contract admin can withdraw funds");
    uint256 balance = address(this).balance;
    payable(admin).transfer(balance);
  }
}
此代码实现了一个简单的IDO代币预售智能合约，具有以下功能：

用户可以使用以太币购买代币，并将购买的代币发送到他们的地址。
智能合约在购买时检查代币的余额，确保不超过大限制，而且购买金额与购买代币数量成比例。
用户可以随时提取他们购买的代币。
智能合约管理员可以随时提取合约收到的以太币。