文件 1 的 1:eightCoin.sol
pragma solidity ^0.6.12;
interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function transfer(address recipient, uint256 amount) external returns (bool);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(address sender, address recipient, uint256 amount) 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 add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b > 0, errorMessage);
uint256 c = a / b;
return c;
}
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
abstract contract Context {
function _msgSender() internal view virtual returns (address payable) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes memory) {
this;
return msg.data;
}
}
contract Ownable is Context {
address private _owner;
address private _previousOwner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
constructor () internal {
address msgSender = _msgSender();
_owner = msgSender;
emit OwnershipTransferred(address(0), msgSender);
}
function owner() public view returns (address) {
return _owner;
}
modifier onlyOwner() {
require(_owner == _msgSender(), "Ownable: caller is not the owner");
_;
}
function renounceOwnership() public virtual onlyOwner {
emit OwnershipTransferred(_owner, address(0));
_owner = address(0);
}
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
contract eightCoin is Context, IERC20, Ownable {
using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint8 private _decimals = 2;
uint256 private _totalSupply = 8000000000 * 10**2;
string private _symbol = "8coin";
string private _name = "8 Coin";
constructor() public {
_balances[_msgSender()] = _totalSupply;
emit Transfer(address(0), _msgSender(), _totalSupply);
}
function getOwner() external view returns (address) {
return owner();
}
function decimals() external view returns (uint8) {
return _decimals;
}
function symbol() external view returns (string memory) {
return _symbol;
}
function name() external view returns (string memory) {
return _name;
}
function totalSupply() external view override returns (uint256) {
return _totalSupply;
}
function balanceOf(address account) external view override returns (uint256) {
return _balances[account];
}
function transfer(address recipient, uint256 amount) external override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
function allowance(address owner, address spender) external view override returns (uint256) {
return _allowances[owner][spender];
}
function approve(address spender, uint256 amount) external override returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
function transferFrom(address sender, address recipient, uint256 amount) external override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "transfer amount exceeds allowance"));
return true;
}
function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
return true;
}
function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "error in decrease allowance"));
return true;
}
function _transfer(address sender, address recipient, uint256 amount) internal {
require(sender != address(0), "transfer sender address is 0 address");
require(recipient != address(0), "transfer recipient address is 0 address");
_balances[sender] = _balances[sender].sub(amount, "transfer balance too low");
_balances[recipient] = _balances[recipient].add(amount);
emit Transfer(sender, recipient, amount);
}
function _approve(address owner, address spender, uint256 amount) internal {
require(owner != address(0), "approve owner is 0 address");
require(spender != address(0), "approve spender is 0 address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
}