Does this function send ether from the contract or from the message sender?

Question

Solidity newbie here...:

 function transfer(address payable to, address sender) public onlyadmin {
         to.transfer(msg.value);

     }

what I want to achieve is sending from the contract's balance so I guess this.balance should be the correct way and not msg.value? Thanks!

Answer 1

Transfer moves money from contract's account to the beneficiary one, while balance is a lookup function that takes one arbitrary address as input and gives back its balance.

msg.value is the amount of Ether send along with the message. If you want to send all money of the contract you have to write something like that:

function f(address payable beneficiary) public {
    beneficiary.transfer(address(this).balance);
}

If you write something like that:

function f(address payable beneficiary) payable public {
    beneficiary.transfer(msg.value);
}

Whenever, the msg.sender sends msg.value Wei to the contract. The latter transfers the money to the beneficiary. In this case the smart contract is a broker that gives the received money to the beneficiary one.