Index

Chapter 8: Back to Attack!

Enough refactoring — back to zombieattack.sol.
We're going to continue defining our attack function, now that we have the ownerOf modifier to use.

Put it to the test

1. Add the ownerOf modifier to attack to make sure the caller owns _zombieId.

2. The first thing our function should do is get a storage pointer to both zombies so we can more easily interact with them:
a. Declare a Zombie storage named myZombie, and set it equal to zombies[_zombieId].
b. Declare a Zombie storage named enemyZombie, and set it equal to zombies[_targetId].

3. We're going to use a random number between 0 and 99 to determine the outcome of our battle. So declare a uint named rand, and set it equal to the result of the randMod function with 100 as an argument.

pragma solidity ^0.4.25;

import "./zombiehelper.sol";

contract ZombieAttack is ZombieHelper {
  uint randNonce = 0;
  uint attackVictoryProbability = 70;

  function randMod(uint _modulus) internal returns(uint) {
    randNonce++;
    return uint(keccak256(abi.encodePacked(now, msg.sender, randNonce))) % _modulus;

  }

  // 1. Add modifier here
  function attack(uint _zombieId, uint _targetId) external ownerOf(_zombieId) {
    // 2. Start function definition here
    Zombie storage myZombie = zombies[_zombieId];
    Zombie storage enemyZombie = zombies[_targetId];
    uint rand = randMod(100);
  }
}