.call{}() in solidity

Question

This is a Smart Contract written in solidity, compiled and deployed in remix

// SPDX-License-Identifier: MIT OR Apache 2.0

pragma solidity ^0.8.8;

contract Payable{

    // payable address can send and receive ethers
    address payable public owner;

    // payable constructor can receive ethers
    constructor() payable{
        owner = payable(msg.sender);
    }

    // this function can receive ethers
    function deposit() public payable{}

    // this cannot accept ethers
    function nonPayable() public{}

    function withdraw() public {
        uint amount = address(this).balance;

        (bool success,) = owner.call{value:amount}("Amount Withdrawn from smart contract");

        require(success,"Failed to receive ether");
    }

    function transfer(address payable _to, uint _amount) public{
        (bool success,) = _to.call{value:_amount}("ether trransferred");
        require(success,"Failed to send ether to address");
    }
}

It is recommended to use .call{}() instead of .transfer() or .send()

I think .call{}() returns a tuple, containing status of transaction and a string memory which stores the string(Amount Withdrawn from smart contract).

If the transaction is successful this string is treated as a data parameter sent as a part of the low-level message call.

What is this low-level message call?

Where could I see this message getting passed in the console?

Is there any other use of this string?

Also I'm bit confused it is string or some function.

Answer 1

call allows to send ether with a selected amount of gas to an Externally Owned Account or to another contract which implements the receive() or fallback() functions.

Additionally, a function in the target contract can be called with the parameter call function has. In this example, we will be calling the myFunction function, with arguments 7 and true:

(bool success, ) = to.call{value: 1 ether, gas: 100000}(abi.encodeWithSignature("myFunction(uint,bool)", 7, true));

If the called function does not match with any function in the target contract, fallback() function will be called. If fallback() does not exist, the success variable returned will be false.