我尝试将用户的事务保存在合同中,如下所示:
function Donar() external payable{
require(msg.value >= MINIMUM, "Minium amount is 0.05");
bool nuevo = false;
blockValue = uint256(blockhash(block.number-1));//is a uint256
//añadimos el nuevo mientro
if(balances[msg.sender]<=0){