正确的部署合约与验证合约的流程

ERC20是一个最基础的发行自己在以太坊上的代币的合约接口。
本教程于2023年08月21日，由于使用的是0.8.20版本，会出现合约部署成功但是验证失败的问题

一般合约写完后的步骤就是

1.部署

2.验证

step0: metaMask钱包连接fantom testnet真实测试网络

Setup Fantom testnet in wallet:

https://docs.fantom.foundation/wallet/set-up-metamask-testnet

Faucet (You can request 5 fantom from here for free): 免费领5个测试币

https://faucet.fantom.network/

step1:编译一份实现了ERC20的合约复制到remix

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.0.0/contracts/token/ERC20/IERC20.sol
interface IERC20 {
    function totalSupply() external view returns (uint);

    function balanceOf(address account) external view returns (uint);

    function transfer(address recipient, uint amount) external returns (bool);

    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint amount) external returns (bool);

    function transferFrom(
        address sender,
        address recipient,
        uint amount
    ) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
}

contract ERC20 is IERC20 {
    uint public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;
    string public name = "G2303465C";
    string public symbol = "YWY";
    uint8 public decimals = 18;

    function transfer(address recipient, uint amount) external returns (bool) {
        balanceOf[msg.sender] -= amount;
        balanceOf[recipient] += amount;
        emit Transfer(msg.sender, recipient, amount);
        return true;
    }

    function approve(address spender, uint amount) external returns (bool) {
        allowance[msg.sender][spender] = amount;
        emit Approval(msg.sender, spender, amount);
        return true;
    }

    function transferFrom(
        address sender,
        address recipient,
        uint amount
    ) external returns (bool) {
        allowance[sender][msg.sender] -= amount;
        balanceOf[sender] -= amount;
        balanceOf[recipient] += amount;
        emit Transfer(sender, recipient, amount);
        return true;
    }

    function mint(uint amount) external {
        balanceOf[msg.sender] += amount;
        totalSupply += amount;
        emit Transfer(address(0), msg.sender, amount);
    }

    function burn(uint amount) external {
        balanceOf[msg.sender] -= amount;
        totalSupply -= amount;
        emit Transfer(msg.sender, address(0), amount);
    }
}

注意，这份代码原本是0.8.20版本，但是经过实践发行，如果用20版本以及20版本的编译器，在高级设置里需要如下设置（EVM的地址以及把代码优化打开）后面的编译器设置都是paris的EVM以及Enable optimization，以及Auto compile

下图以0.8.19版本的编译器配置为例：