ERC20代币想必大家不陌生了，在以太坊上有数以千计的ERC20代币！本着学以致用的目的，自己也发个币装一把。
先上代码：
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| pragma solidity >=0.4.22 <0.7.0;
abstract contract ERC20Interface {
string public name;
string public symbol;
uint8 public decimals;
uint public totalSupply;
function transfer(address _to, uint256 _value) public virtual returns (bool success);
function transferFrom(address _from, address _to, uint256 _value) public virtual returns (bool success);
function approve(address _spender, uint256 _value) public virtual returns (bool success);
function allowance(address _owner, address _spender) public virtual view returns (uint256 remaining);
event Transfer(address indexed _from, address indexed _to, uint256 _value);
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}
contract ERC20 is ERC20Interface {
mapping(address => uint256) public balanceOf;
mapping(address => mapping(address => uint256)) allowed;
constructor() public {
name = "Lemool";
symbol = "LEM";
decimals = 0;
totalSupply = 10000000;
balanceOf[msg.sender] = totalSupply;
}
function transfer(address _to, uint256 _value) public override returns (bool success) {
require(_to != address(0));
require(balanceOf[msg.sender] >= _value);
require(balanceOf[ _to] + _value >= balanceOf[ _to]);
balanceOf[msg.sender] -= _value;
balanceOf[_to] += _value;
emit Transfer(msg.sender, _to, _value);
return true;
}
function transferFrom(address _from, address _to, uint256 _value) public override returns (bool success) {
require(_to != address(0));
require(allowed[_from][msg.sender] >= _value);
require(balanceOf[_from] >= _value);
require(balanceOf[ _to] + _value >= balanceOf[ _to]);
balanceOf[_from] -= _value;
balanceOf[_to] += _value;
allowed[_from][msg.sender] -= _value;
emit Transfer(msg.sender, _to, _value);
return true;
}
function approve(address _spender, uint256 _value) public override returns (bool success) {
allowed[msg.sender][_spender] = _value;
emit Approval(msg.sender, _spender, _value);
return true;
}
function allowance(address _owner, address _spender) public override view returns (uint256 remaining) {
return allowed[_owner][_spender];
}
}
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ERC20是有标准接口的，其实都很简单，就是几个参数和几个转帐的方法！想当年很多项目就是靠着这几行代码卷钱无数，现在想来会不会有点后悔呢。
在上面转帐的方法还是自己实现了一下，其实还有一种更简单和安全的方法：OpenZeppelin。只有少数几行代码就可以实现ERC20代币合约！
用前先安装一下：npm install @openzeppelin/contracts
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| pragma solidity >=0.4.22 <0.7.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20Detailed.sol";
contract TutorialToken is ERC20, ERC20Detailed {
constructor() ERC20Detailed("Lemool", "LEM", 0) public {
_mint(msg.sender, 10000000);
}
}
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短短五六行代码就全搞定了，想想是不是很牛啊！感兴趣的朋友可以一试！
This page is synchronized from the post: ‘ERC20代币合约 / 学习智能合约#5’