Blockchain By Example

The complete token contract

Having added the code to support delegated transfers, we now have a complete implementation of our ERC-20 token:

pragma solidity ^0.4.24; contract PacktToken {    string public name = 'Packt ERC20 Token';    string public symbol = 'PET';     uint256 public totalSupply;    mapping (address => uint256) public balanceOf;    mapping(address => mapping(address => uint256)) public allowance;     event Transfer(address indexed _from,                   address indexed _to,                   uint256 _value);     event Approval(address indexed _owner,                   address indexed _spender,                   uint256 _value);     constructor(uint256 _initialSupply) public {        balanceOf[msg.sender] = _initialSupply;        totalSupply = _initialSupply;        emit Transfer(address(0), msg.sender, totalSupply);    }  function transfer(address ...