delegatecall 调用失败

[superwildboy]

##练习23 delegatecall 调用合约C失败
function delegatecallSetVars(address _addr, uint _num) external payable{
// delegatecall setVars()
(bool success, bytes memory data) = _addr.delegatecall(
abi.encodeWithSignature("setVars(uint256)", _num)
);
if(!success){
num = _num;
}
}

[0xEyu]

我试了下没报错，这样用没问题，可能你是想调用call来改变另一个合约的值，delegatecall和call是有区别的