Canto contest - AkshaySrivastav's results

1. In the withdraw function, due to Line 135 _amount value can never exceed earnedFees, the Line 137 can be put inside an unchecked block.

135        if (_amount > earnedFees) _amount = earnedFees;
137
137        balances[_tokenId] = earnedFees - _amount;

2. At L50, L87 and L108 the msg.sender value is stored in an address variable in memory. This value is then read and used at multiple places. It is recommended to use msg.sender directly without storing/reading from memory to save gas.

    function register(address _recipient) public onlyUnregistered returns (uint256 tokenId) {
        address smartContract = msg.sender;

        // code clipped...

        emit Register(smartContract, _recipient, tokenId);

        feeRecipient[smartContract] = NftData({
            tokenId: tokenId,
            registered: true
        });
    }

3. It is recommended to simply use a uint256 variable instead if Counters library to save gas.

4. <x> += <y> costs more gas than <x> = <x> + <y> for state variables.

        balances[_tokenId] += msg.value;