Solidity – What Happens to msg.value if require Fails in Solidity

ethersolidity

Imagine I have a function that looks something like this. Is the ether refunded to the sender (invoker) if require fails?

function foo(uint _minShares) public {
        uint256 ethReserveBeforeDeposit = address(this).balance - msg.value;
        // compute proportion of deposited ether and total ether balance to determine amount of shares
        uint256 sharesMinted = (msg.value / ethReserveBeforeDeposit) * totalSupply();
        require(sharesMinted >= _minShares);
        // what happens if require fail, is msg.value refunded?
    }

Best Answer

Just tested it out on remix.ethereum

first of all the foo function must have the keyword payable to receive ether
If require fails the the initial sent ether to foo function will be refunded but gas will still be used till the require statement is reached.

Related Solutions

Solidity – Handling Unimplemented Functions in Contracts

The problem is that totalSupply() implementation is missing. Seems like autogenerated getters do not count. So you need to explicitly create the function.

contract StandardToken is Token {
    uint256 _totalSupply;

    function totalSupply() constant returns (uint256 totalSupply) {
        totalSupply = _totalSupply;
    }
}

Ether Transactions – Comparing msg.value to Variable Ether in Remix

You can not do variable ether instead do:

function transfer_ether() public payable{
   uint c = 60 ether;
   if(msg.value >= c){
       // here your code
   }
}

Hope this helps

EDIT: The second part of the question added as an edit by OP

You can not do uint public c ether the compiler should be telling this.

You need to establish what the subject is inputting. If the subject is requested to input amount in ether, then you should transform it to wei (this is what using the word ether does when you do 60 ether)

Therefore your function should be:

uint public c;
function set_c(uint _c){
    c=_c*10**18 ;
}

This is because 1 ether = 10**18 wie. The smart contract makes all the calculations related to ether in wei. So if the subject inputs as value the number 1, c will save 10**18 = 1000000000000000000, which is the equivalent in wei for 1 teher.

Hope this helps

Best Answer

Related Solutions

Solidity – Handling Unimplemented Functions in Contracts

Ether Transactions – Comparing msg.value to Variable Ether in Remix

Related Topic