Receive

Receive()

• It cannot have arguments.

• It cannot return data.

• It has external visibility and is marked payable.

The receive method is used as a fallback function in a contract and is called when ether is sent to a contract with no calldata. If the receive method does not exist, it will use the fallback function.

//SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

contract FunctionsExample {

    mapping(address => uint) public balanceReceived;

    function receiveMoney() public payable {
        assert(balanceReceived[msg.sender] + msg.value >= balanceReceived[msg.sender]);
        balanceReceived[msg.sender] += msg.value;
    }

    function withdrawMoney(address payable _to, uint _amount) public {
        require(_amount <= balanceReceived[msg.sender], "not enough funds.");
        assert(balanceReceived[msg.sender] >= balanceReceived[msg.sender] - _amount);
        balanceReceived[msg.sender] -= _amount;
        _to.transfer(_amount);
    }

    receive() external payable{
        receiveMoney();
    } 

}

• receive() external payable — for empty calldata

• fallback() external payable — when no other function matches (not even the receive function). Optionally payable.

Links:

• https://blog.finxter.com/what-is-payable-in-solidity/