ERC20 元数据（metadata）、铸造（mint）、销毁（burn）功能
//SPDX-License-Identifier:GPL-3.0
pragma solidity ^0.8.17;
interface IERC20 {
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function transfer(address to, uint256 amount) external returns (bool);
function transferFrom(address from, address to, uint256 amount) external returns (bool);
}
contract ERC20 is IERC20 {
uint256 _totalSupply;
mapping(address => uint256) _balance;
mapping(address => mapping(address => uint256)) _allowance;
string _name;
string _symbol;
address _owner;
modifier onlyOwner() {
require(_owner == msg.sender, "ERROR: only owner can access this function");
_;
}
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
_owner = msg.sender;
_balance[msg.sender] = 10000;
_totalSupply = 10000;
}
function mint(address account, uint256 amount) public onlyOwner {
require(account != address(0), "ERROR: mint to address 0");
_totalSupply += amount;
_balance[account] += amount;
emit Transfer(address(0), account, amount);
}
function burn(address account, uint256 amount) public onlyOwner {
require(account != address(0), "ERROR: burn from address 0");
_totalSupply -= amount;
uint256 accountBalance = _balance[account];
require(accountBalance >= amount, "ERROR: no more token to burn");
_balance[account] = accountBalance - amount;
emit Transfer(account, address(0), amount);
}
function name() public view returns (string memory) {
return _name;
}
function symbol() public view returns (string memory) {
return _symbol;
}
function decimals() public pure returns (uint8) {
return 18;
}
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
function balanceOf(address account) public view returns (uint256) {
return _balance[account];
}
function _transfer(address from, address to, uint256 amount) internal {
uint256 myBalance = _balance[from];
require(myBalance >= amount, "No money to transfer");
require(to != address(0), "Transfer to address 0");
_balance[from] = myBalance - amount;
_balance[to] = _balance[to] + amount;
emit Transfer(from, to, amount);
}
function transfer(address to, uint256 amount) public returns (bool) {
_transfer(msg.sender, to, amount);
return true;
}
function allowance(address owner, address spender) public view returns (uint256){
return _allowance[owner][spender];
}
function _approve(address owner, address spender, uint256 amount) internal {
_allowance[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
function approve(address spender, uint256 amount) public returns (bool) {
_approve(msg.sender, spender, amount);
return true;
}
function transferFrom(address from, address to, uint256 amount) public returns (bool) {
uint256 myAllowance = _allowance[from][msg.sender];
require(myAllowance >= amount, "ERROR:myAllowance < amount");
_approve(from, msg.sender, myAllowance - amount);
_transfer(from, to, amount);
return true;
}
}