BlogEthereum How to Create a Burnable Token
pragma solidity ^0.5.0;
// ----------------------------------------------------------------------------
// 'Test' token contract
//
// Deployed to : Your Wallet number to send
// Symbol : TST
// Name : Test Project
// Total supply: 500000
// Decimals : 8
//
// Enjoy.
//
// (c) by Moritz Neto with BokkyPooBah / Bok Consulting Pty Ltd Au 2017. The MIT Licence.
// ----------------------------------------------------------------------------
interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address who) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function transfer(address to, uint256 value) external returns (bool);
function approve(address spender, uint256 value) external returns (bool);
function transferFrom(address from, address to, uint256 value) external returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
library SafeMath {
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
uint256 c = a * b;
assert(c / a == b);
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a / b;
return c;
}
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
assert(b <= a);
return a - b;
}
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
assert(c >= a);
return c;
}
function ceil(uint256 a, uint256 m) internal pure returns (uint256) {
uint256 c = add(a,m);
uint256 d = sub(c,1);
return mul(div(d,m),m);
}
}
contract ERC20Detailed is IERC20 {
string private _name;
string private _symbol;
uint8 private _decimals;
constructor(string memory name, string memory symbol, uint8 decimals) public {
_name = name;
_symbol = symbol;
_decimals = decimals;
}
function name() public view returns(string memory) {
return _name;
}
function symbol() public view returns(string memory) {
return _symbol;
}
function decimals() public view returns(uint8) {
return _decimals;
}
}
contract Owned {
address public owner;
address public newOwner;
event OwnershipTransferred(address indexed _from, address indexed _to);
constructor() public {
owner = msg.sender;
}
modifier onlyOwner {
require(msg.sender == owner);
_;
}
function transferOwnership(address _newOwner) public onlyOwner {
newOwner = _newOwner;
}
function acceptOwnership() public {
require(msg.sender == newOwner);
emit OwnershipTransferred(owner, newOwner);
owner = newOwner;
newOwner = address(0);
}
}
contract Test is ERC20Detailed, Owned, SafeMath {
using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowed;
string constant tokenName = "Test Project";
string constant tokenSymbol = "TST";
uint8 constant tokenDecimals = 8;
uint256 _totalSupply = 500000*10**8;
uint256 public basePercent = 1000;
uint256 public _burnStopAmount;
uint256 public _lastTokenSupply;
constructor() public payable ERC20Detailed(tokenName, tokenSymbol, tokenDecimals) {
_mint(msg.sender, _totalSupply);
_burnStopAmount = 0;
_lastTokenSupply = 200000 * 10**8;
}
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
function balanceOf(address owner) public view returns (uint256) {
return _balances[owner];
}
function allowance(address owner, address spender) public view returns (uint256) {
return _allowed[owner][spender];
}
function findOnePercent(uint256 value) public view returns (uint256) {
uint256 roundValue = value.ceil(basePercent);
uint256 onePercent = roundValue.mul(basePercent).div(10000);
return onePercent;
}
function transfer(address to, uint256 value) public returns (bool) {
require(value <= _balances[msg.sender]);
require(to != address(0));
uint256 tokensToBurn = findOnePercent(value);
uint256 tokensToTransfer = value.sub(tokensToBurn);
_balances[msg.sender] = _balances[msg.sender].sub(value);
_balances[to] = _balances[to].add(tokensToTransfer);
_totalSupply = _totalSupply.sub(tokensToBurn);
emit Transfer(msg.sender, to, tokensToTransfer);
emit Transfer(msg.sender, address(0), tokensToBurn);
return true;
}
function multiTransfer(address[] memory receivers, uint256[] memory amounts) public {
for (uint256 i = 0; i < receivers.length; i++) {
transfer(receivers[i], amounts[i]);
}
}
function approve(address spender, uint256 value) public returns (bool) {
require(spender != address(0));
_allowed[msg.sender][spender] = value;
emit Approval(msg.sender, spender, value);
return true;
}
function transferFrom(address from, address to, uint256 value) public returns (bool) {
require(value <= _balances[from]);
require(value <= _allowed[from][msg.sender]);
require(to != address(0));
_balances[from] = _balances[from].sub(value);
uint256 tokensToBurn = findOnePercent(value);
uint256 tokensToTransfer = value.sub(tokensToBurn);
_balances[to] = _balances[to].add(tokensToTransfer);
_totalSupply = _totalSupply.sub(tokensToBurn);
_allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
emit Transfer(from, to, tokensToTransfer);
emit Transfer(from, address(0), tokensToBurn);
return true;
}
function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
require(spender != address(0));
_allowed[msg.sender][spender] = (_allowed[msg.sender][spender].add(addedValue));
emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
return true;
}
function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
require(spender != address(0));
_allowed[msg.sender][spender] = (_allowed[msg.sender][spender].sub(subtractedValue));
emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
return true;
}
function _mint(address account, uint256 amount) internal {
require(amount != 0);
_balances[account] = _balances[account].add(amount);
emit Transfer(address(0), account, amount);
}
function burn(uint256 amount) external {
_burn(msg.sender, amount);
}
function _burn(address account, uint256 amount) internal {
require(amount != 0);
require(amount <= _balances[account]);
_totalSupply = _totalSupply.sub(amount);
_balances[account] = _balances[account].sub(amount);
emit Transfer(account, address(0), amount);
}
function burnFrom(address account, uint256 amount) external {
require(amount <= _allowed[account][msg.sender]);
_allowed[account][msg.sender] = _allowed[account][msg.sender].sub(amount);
_burn(account, amount);
}
}