// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
import "hardhat/console.sol";
//ERC20 同质化代币，每个代币的本质或性质都是相同
//ETH 是原生代币，它不是ERC20代币,它们两是不能协同工作。所以需要将ETH转换成WETH(ERC20)
//ERC20 必须实现相应的接口(规范),参见 https://eips.ethereum.org/EIPS/eip-20
//totalSupply 代币发行总供应量，它即可以固定不变，又可以根据业务需求而改变
//totalSupply 代币发行总供应量是否可变，取决于合约是否存在mint或burn函数/方法
//balanceOf(owner) 获取某个账户的余额，所有账户余额的总和必须等于totalSupply
//approve 授权一定数量的代币给第三方/交易所/代理人。注意，是授权而不是发送代币给第三方
//approve 必须包含3个参数，Owner:谁授权代币给第三方，Spender:第三方/交易所/代理人,Amount:授权数额
//allowance 保存approve方法的3项数据
//transfer 转账，接收2个参数，from:msg.sender; to:转入; amount:金额
//transferFrom 转账，接收3个参数，from:转出; to:转入; amount:金额
//transfer与transferFrom使用场景不一样，transfer用在本合约转账，transferFrom用在第三方/去中心交易所/代理人
//event Approval与Transfer 将交易等日志信息写入区块链，非常重要
//V1
interface IERC20V1 {
event Approval(address indexed owner ,address indexed spender ,uint256 amount);
event Transfer(address indexed from ,address indexed to ,uint256 amount);
function name() external pure returns (string memory);
function symbol() external pure returns (string memory);
function decimals() external pure returns (uint8);
//对应状态变量totalSupply 代币发行总供应量
function totalSupply() external view returns(uint256);
//balanceOf(owner) 获取某个账户的余额
function balanceOf(address owner) external view returns(uint256);
//approve 授权一定数量的代币给第三方/交易所/代理人
function approve(address spender, uint amount) external returns (bool);
//allowance 保存approve方法的3项数据
function allowance(address owner, address spender) external view returns (uint256);
function transfer(address to, uint amount) external returns(bool);
function transferFrom(address from, address to,uint amount) external returns(bool);
}
contract ERC20V1 is IERC20V1 {
string public constant name = "XingZheChain";
string public constant symbol = "XZC";
uint8 public constant decimals = 18;
//totalSupply 代币发行总供应量
uint256 public totalSupply;
mapping(address => uint256) public balanceOf;
address public _owner;
mapping(address => mapping(address => uint256)) public allowance;
constructor(uint256 _initTotalSupply){
_owner = msg.sender;
//预挖给创建者代币
mint(msg.sender,_initTotalSupply);
}
modifier onlyOwner() {
require(_owner == msg.sender,"Ownable:caller is not the owner");
_;
}
//挖掘出新代币以及挖给那个地址
//合约创建者调用
function mint(address to ,uint256 amount) public onlyOwner {
totalSupply = totalSupply += amount;
balanceOf[to] = balanceOf[to] += amount;
}
//燃烧自己的代币
function burn(uint256 amount) public {
address from = msg.sender;
balanceOf[from] = balanceOf[from] -= amount;
totalSupply = totalSupply -= amount;
}
function _approve(address owner, address spender, uint amount) private {
allowance[owner][spender] = amount;
emit Approval(owner ,spender ,amount);
}
function approve(address spender, uint amount) external returns(bool) {
_approve(msg.sender, spender, amount);
return true;
}
function _transfer(address from, address to,uint amount) private {
balanceOf[from] = balanceOf[from] -= amount;
balanceOf[to] = balanceOf[to] += amount;
emit Transfer(from ,to ,amount);
}
function transfer(address to, uint amount) external returns(bool){
_transfer(msg.sender, to, amount);
return true;
}
function transferFrom(address from, address to,uint amount) external returns(bool){
uint256 currentAllowance = allowance[from][msg.sender];
require(currentAllowance >= amount,"ERC20: insufficient allowance");
allowance[from][msg.sender] = currentAllowance -= amount;
//console.log("msg.sender ->",address(msg.sender));
_transfer(from ,to ,amount);
return true;
}
}
//建议去中心化交易所
contract Dex {
address public erc20V1;
constructor(address _erc20V1){
erc20V1 = _erc20V1;
}
function transferFromTo(address to ,uint amount) external {
IERC20V1(erc20V1).transferFrom(msg.sender ,to ,amount);
}
function transferTo(address to,uint amount) external {
IERC20V1(erc20V1).transfer(to,amount);
}
}
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