solidity 合约中的数学运算

Question

我想创建一个 solidity 函数，从 A 处接收金额，使用合约账户余额将收到的金额翻倍，然后将翻倍的金额转账给 B。到目前为止，我创建的函数是只从 A 那里收到外部应付金额，我注意到放置的金额应该 > 2 以太币，但是对于加倍和转移金额，我对这个方法有点困惑。

    contract MyContract {
    address payable public personA;
    address payable public personB;
    mapping(address => uint) balances;
    modifier onlyonlypersonA() {
        require(msg.sender == onlypersonA, "Only onlypersonA can call this method");
        _;}       
   function Send() onlypersonA external payable {
        if(msg.value < 2 ether) {revert();} 
        balances[msg.sender] += msg.value;}
}

Answer 1

试试这个：


  contract MyContract {
    address payable public personA;
    address payable public personB;
    mapping(address => uint) balances;
    modifier onlyonlypersonA() {
        require(msg.sender == onlypersonA, "Only onlypersonA can call this method");
        _;}       
   function Send() onlypersonA external payable {
        if(msg.value < 2 ether) {revert();} 
        balances[msg.sender] += msg.value;

        // Try doubling
        require(msg.value * 2 <= address(this).balance, "Insufficient funds to doubling");
        personB.transfer(msg.value * 2);
   }
}

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