solidity--fallback

https://solidity-by-example.org/fallback/

fallback is a function that takes no arguments and returns nothing.

 It executes when a function that does not exist or ether is sent directly to the contract, but receive() does not exist or msg.data is not empty fallback is called with a limit of 2300 gas when transfer or send is called.

fallback

是一个不接受任何参数且不返回任何内容的函数。

它在何时执行

• 调用不存在的函数或

• 以太币直接发送到合约，但

  receive()

  不存在或

  msg.data

  不为空

fallback

被调用时有 2300 气体限制

transfer

或者

send

.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;

contract Fallback {
    event Log(uint gas);

    // Fallback function must be declared as external.
    fallback() external payable {
        // send / transfer (forwards 2300 gas to this fallback function)
        // call (forwards all of the gas)
        emit Log(gasleft());
    }

    // Helper function to check the balance of this contract
    function getBalance() public view returns (uint) {
        return address(this).balance;
    }
}

contract SendToFallback {
    function transferToFallback(address payable _to) public payable {
        _to.transfer(msg.value);
    }

    function callFallback(address payable _to) public payable {
        (bool sent, ) = _to.call{value: msg.value}("");
        require(sent, "Failed to send Ether");
    }
}