05-1-ERC20

ERC20

Any contract that follow the ERC20 standard is a ERC20 token.

ERC20 tokens provide functionalities to

• transfer tokens
• allow others to transfer tokens on behalf of the token holder

Here is the interface for ERC20.

任何遵循ERC20标准的合约都是ERC20代币。

ERC20 代币提供的功能

• 转移代币
• 允许其他人代表代币持有者转让代币 这是ERC20的接口。

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

// 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);
}

2.ERC20代币合约示例。

Example of ERC20 token contract.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import "./IERC20.sol";

contract ERC20 is IERC20 {
    uint public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;
    string public name = "Solidity by Example";
    string public symbol = "SOLBYEX";
    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);
    }
}