Challenge 20

Calldata vs memory

LowSolidity basics

Challenge

A function takes an array argument and later uses it in a storage-impacting way. Which data location is safer for unmodified external inputs?

Starter code

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

contract DataLocationDemo {
  uint256[] public values;

  function addValues(uint256[] memory input) public {
    for (uint256 i = 0; i < input.length; i++) {
      values.push(input[i]);
    }
  }
}

Show hint

External data that is not modified should usually be read from calldata when possible.