Index

CryptoZombies

  1. Lesson 1: CryptoZombies
    1. Chapter 2 Contracts
    2. Chapter 3: State Variables & Integers
    3. Chapter 4: Math Operations
    4. Chapter 5: Structs
    5. Chapter 6: Arrays
    6. Chapter 7: Function Declarations
    7. Chapter 8: Working With Structs and Arrays
    8. Chapter 9: Private / Public Functions
    9. Chapter 10: More on Functions
    10. Chapter 11: Keccak256 and Typecasting
    11. Chapter 12: Putting It Together
    12. Chapter 13: Events
    13. Chapter 14: Web3.js
  2. Lesson 2: Zombies Attack Their Victims
    1. Chapter 2: Mappings and Addresses
    2. Chapter 3: Msg.sender
    3. Chapter 4: Require
    4. Chapter 5: Inheritance
    5. Chapter 6: Import
    6. Chapter 7: Storage vs Memory
    7. Chapter 8: Zombie DNA
    8. Chapter 9: More on Function Visibility
    9. Chapter 10: What Do Zombies Eat?
    10. Chapter 11: Using an Interface
    11. Chapter 12: Handling Multiple Return Values
    12. Chapter 13: Bonus: Kitty Genes
    13. Chapter 14: Wrapping It Up
  3. Lesson 3: Advanced Solidity Concepts
    1. Chapter 2: Ownable Contracts
    2. Chapter 3: onlyOwner Function Modifier
    3. Chapter 4: Gas
    4. Chapter 5: Time Units
    5. Chapter 6: Zombie Cooldowns
    6. Chapter 7: Public Functions & Security
    7. Chapter 8: More on Function Modifiers
    8. Chapter 9: Zombie Modifiers
    9. Chapter 10: Saving Gas With 'View' Functions
    10. Chapter 11: Storage is Expensive
    11. Chapter 12: For Loops
    12. Chapter 13: Wrapping It Up
  4. Lesson 4: Zombie Battle System
    1. Chapter 1: Payable
    2. Chapter 2: Withdraws
    3. Chapter 3: Zombie Battles
    4. Chapter 4: Random Numbers
    5. Chapter 5: Zombie Fightin'
    6. Chapter 6: Refactoring Common Logic
    7. Chapter 7: More Refactoring
    8. Chapter 8: Back to Attack!
    9. Chapter 9: Zombie Wins and Losses
    10. Chapter 10: Zombie Victory 😄
    11. Chapter 11: Zombie Loss 😞
  5. Lesson 5: ERC721 & Crypto-Collectibles
    1. Chapter 1: Tokens on Ethereum
    2. Chapter 2: ERC721 Standard, Multiple Inheritance
    3. Chapter 3: balanceOf & ownerOf
    4. Chapter 4: Refactoring
    5. Chapter 5: ERC721: Transfer Logic
    6. Chapter 6: ERC721: Transfer Cont'd
    7. Chapter 7: ERC721: Approve
    8. Chapter 8: ERC721: Approve
    9. Chapter 9: Preventing Overflows
    10. Chapter 10: SafeMath Part 2
    11. Chapter 11: SafeMath Part 3
    12. Chapter 12: SafeMath Part 4
    13. Chapter 13: Comments
    14. Chapter 14: Wrapping It Up
  6. App Front-ends & Web3.js
    1. Chapter 1: Intro to Web3.js
    2. Chapter 2: Web3 Providers
    3. Chapter 3: Talking to Contracts
    4. Chapter 4: Calling Contract Functions
    5. Chapter 5: Metamask & Accounts
    6. Chapter 6: Displaying our Zombie Army
    7. Chapter 7: Sending Transactions
    8. Chapter 8: Calling Payable Functions
    9. Chapter 9: Subscribing to Events
    10. Chapter 10: Wrapping It Up

Chapter 5: Structs


Chapter 5: Structs


Sometimes you need a more complex data type. For this, Solidity provides structs:
struct Person {
  uint age;
  string name;
}


Structs allow you to create more complicated data types that have multiple properties.
Note that we just introduced a new type, string. Strings are used for arbitrary-length UTF-8 data. Ex. string greeting = "Hello world!"

Put it to the test


In our app, we're going to want to create some zombies! And zombies will have multiple properties, so this is a perfect use case for a struct.
1. Create a struct named Zombie.

2. Our Zombie struct will have 2 properties: name (a string), and dna (a uint).

pragma solidity ^0.4.25;

contract ZombieFactory {

    uint dnaDigits = 16;
    uint dnaModulus = 10 ** dnaDigits;

    struct Zombie {
        string name;
        uint dna;
    }

}