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solidity实现ERC20代币标准

article 2024/9/23 19:26:46

文章目录

1、以太坊 - 维基百科
2、IERC20
3、ERC20
4、Remix 编译部署

1、以太坊 - 维基百科

以太坊（Ethereum）是一个去中心化的开源的有智能合约功能的公共区块链平台。以太币（ETH 或 Ξ）是以太坊的原生加密货币。截至2021年12月，以太币是市值第二高的加密货币，仅次于比特币。以太坊是使用最多的区块链，主要的代币标准有 ERC-20、ERC-721、ERC-1155、ERC-223、ERC-677 等等，其中 ERC-20 是最常用的代币标准。

2、IERC20

IERC20 是 ERC20 标准的接口规范，它定义和规范了一个标准 ERC20 代币合约应该实现的功能。这里让 ERC20 合约直接继承自 IERC20 接口。

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;


interface IERC20 { 
    // 当 `value` 单位的货币从账户 (`from`) 转账到另一账户 (`to`)时 触发
    event Transfer(address indexed from, address indexed to, uint256 value);
    // 当 `value` 单位的货币从账户 (`owner`) 授权给另一账户 (`spender`)时触发 
    event Approval(address indexed owner, address indexed spender, uint256 value);
    
    // 返回代币总供给.
    function totalSupply() external view returns (uint256);

    // 返回账户`account`所持有的代币数.
    function balanceOf(address account) external view returns (uint256);

    // 转账 `amount` 单位代币，从调用者账户到另一账户 `to`.
    function transfer(address to, uint256 amount) external returns (bool);

    // 返回`owner`账户授权给`spender`账户的额度，默认为0。
    function allowances(address owner, address spender) external view returns (uint256);

    // 调用者账户给`spender`账户授权 `amount`数量代币。    
    function approve(address spender, uint256 amount) external returns (bool);

    // 通过授权机制，从`from`账户向`to`账户转账`amount`数量代币。转账的部分会从调用者的`allowances`中扣除。
    function transferFrom( address from, address to, uint256 amount ) external returns (bool);
}

3、ERC20

ERC20 是以太坊上最常用的代币标准,用于发行同质化代币。它定义了一套规则和接口,使得不同的代币可以在同一个平台上互相交换和使用。ERC-20 定义的代币实现了基本功能如转账、查询余额、授权、总供给量等。

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

import "./IERC20.sol"; 

contract MyToken is IERC20 {
    mapping(address => uint256) public override balanceOf;
    mapping(address => mapping(address => uint256)) public override allowances;

    uint256 public totalSupply;     // 代币总供给
    string public name;             // 代币名称
    string public symbol;           // 代币代号
    uint8 public decimals = 18;     // 小数位数

    // 构造函数 
    constructor(string memory name_, string memory symbol_) {
        name = name_;
        symbol = symbol_;
    }


    // 转账
    function transfer(address recipient, uint256 amount) public override returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    // 授权转账 
    function transferFrom(address sender, address recipient, uint amount) external override returns (bool){
        _transfer(sender, recipient, amount); 

        uint256 currentAllowance = allowances[sender][msg.sender]; 
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowances");           // 是否超过授权额度 
        
        _approve(sender, msg.sender, currentAllowance - amount);
        return true;
    }   


    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        uint256 senderBalance = balanceOf[sender];
        require(senderBalance >= amount,  "ERC20: transfer amount exceeds balance");

        balanceOf[sender] = senderBalance - amount;
        balanceOf[recipient] += amount;

        emit Transfer(sender, recipient, amount);
    }

    // 授权 
    function approve(address spender, uint amount) external override returns (bool){
        _approve(msg.sender, spender, amount); 
        return true;
    }

    function _approve(address owner, address spender, uint256 amount) internal {
        require(owner != address(0), "ERC20: approve from the zero address");   // 授权无效地址 
        require(spender != address(0), "ERC20: approve to the zero address");

        allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }


    // 锻造代币
    function mint(address account, uint amount) external {
        require(account != address(0), "ERC20: mint to the zero address");
        balanceOf[account] += amount; 
        totalSupply += amount;
        emit Transfer(address(0), msg.sender, amount);
    }

    // 销毁代币 
    function burn(address account, uint amount) external {
        require(account != address(0), "ERC20: burn from the zero address");

        uint256 accountBalance = balanceOf[account]; 
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");

        balanceOf[account] = accountBalance - amount;
        totalSupply -= amount; 
        emit Transfer(account, address(0), amount); 
    }
}