Ethereum Cookbook

How to do it…

1. Extend the ERC20 contract to create a new burnable token contract:

pragma solidity ^0.4.23;import "./ERC20.sol";contract Burnable is ERC20 {    ...}

2. Create a function that can be called by the user to burn some tokens:

function burn(uint256 _value) public { }

3. Verify whether the sender has enough balance to burn:

require(_value <= balances[msg.sender]);

4. While burning tokens, subtract the number of tokens burnt from the balance of the current holder and from total supply:

balances[_who] = balances[_who].sub(_value); totalSupply_ = totalSupply_.sub(_value);

5. Emit an event for every token burning transaction. Create a burn event with the sender address and value as parameters:

// Event declarationevent Burn(address indexed ...