区块链是怎么融资

pragma solidity ^0.8.0;

contract ICO {
    string public name = "MyTokenICO";
    string public symbol = "MTK";
    uint256 public totalSupply;
    uint256 public tokenPrice;
    address payable public wallet;

    mapping(address => uint256) public balanceOf;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor(uint256 _totalSupply, uint256 _tokenPrice, address payable _wallet) {
        totalSupply = _totalSupply;
        tokenPrice = _tokenPrice;
        wallet = _wallet;
        balanceOf[msg.sender] = totalSupply;
    }

    function buyTokens(uint256 _amount) public payable {
        uint256 cost = _amount * tokenPrice;
        require(msg.value >= cost, "Insufficient funds");
        require(balanceOf[address(this)] >= _amount, "Not enough tokens left");

        balanceOf[msg.sender] += _amount;
        balanceOf[address(this)] -= _amount;
        wallet.transfer(msg.value);

        emit Transfer(address(this), msg.sender, _amount);
    }

    // 其他必要函数如transfer, approve等省略...
}