Index

Chapter 5: Zombie Fightin'

Now that we have a source of some randomness in our contract, we can use it in our zombie battles to calculate the outcome.
Our zombie battles will work as follows:
• You choose one of your zombies, and choose an opponent's zombie to attack.
• If you're the attacking zombie, you will have a 70% chance of winning. The defending zombie will have a 30% chance of winning.
• All zombies (attacking and defending) will have a winCount and a lossCount that will increment depending on the outcome of the battle.
• If the attacking zombie wins, it levels up and spawns a new zombie.
• If it loses, nothing happens (except its lossCount incrementing).
• Whether it wins or loses, the attacking zombie's cooldown time will be triggered.
This is a lot of logic to implement, so we'll do it in pieces over the coming chapters.

Put it to the test

1. Give our contract a uint variable called attackVictoryProbability, and set it equal to 70.

2. Create a function called attack. It will take two parameters: _zombieId (a uint) and _targetId (also a uint). It should be an external function.

Leave the function body empty for now.

zombieattack.sol

pragma solidity ^0.4.25;

import "./zombiehelper.sol";

contract ZombieAttack is ZombieHelper {
  uint randNonce = 0;
  // Create attackVictoryProbability here

  uint attackVictoryProbability = 70;

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

  // Create new function here

  function attack(uint _zombieId, uint _targetId) external {

  }
}