Challenge 4

Gas Optimization & Storage Refunds

GasGas optimization

Challenge

What do you think the gas costs will be when setting this value to a new number and then resetting it to zero?

Starter code

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract GasTest {
  uint256 public number;

  function setNumber(uint256 _num) public {
    number = _num;
  }
}

Show hint

Storage writes cost gas, but clearing a nonzero storage slot may receive a refund. Compare the transactions.