Solidity 练习：Call
睡不醒的鲤鱼 2022-12-29 Web3 Solidity
# 一、题目说明
call 是调用其他合约的低级函数。下面给出被调用合约的内容。
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;
contract TestCall {
fallback() external payable {}
function foo(
string memory _message,
uint _x
) external payable returns (bool) {
return true;
}
bool public barWasCalled;
function bar(uint _x, bool _b) external {
barWasCalled = true;
}
}
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# 二、任务列表
- 完成 callBar 函数。使用 call 去执行 TestCall.bar 并传入你选择的输入。
# 三、解答代码
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.17;
contract Call {
function callFoo(address payable _addr) external payable {
// You can send ether and specify a custom gas amount
// returns 2 outputs (bool, bytes)
// bool - whether function executed successfully or not (there was an error)
// bytes - any output returned from calling the function
(bool success, bytes memory data) = _addr.call{
value: msg.value,
gas: 5000
}(abi.encodeWithSignature("foo(string,uint256)", "call foo", 123));
require(success, "tx failed");
}
// Calling a function that does not exist triggers the fallback function, if it exists.
function callDoesNotExist(address _addr) external {
(bool success, bytes memory data) = _addr.call(
abi.encodeWithSignature("doesNotExist()")
);
}
function callBar(address _addr) external {
(bool success, ) = _addr.call(
abi.encodeWithSignature("bar(uint256,bool)", 123, true)
);
require(success, "tx failed");
}
}
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