ERC20智能合约demo

ERC20智能合约demo

• ERC20.sol
• IERC20.sol

ERC20.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
import {IERC20} from "./IERC20.sol";

contract ERC20 is IERC20{
    mapping(address => uint256) public override balanceOf;
	mapping(address => mapping(address => uint256)) public override allowance;

    uint256 public override totalSupply;   // 代币总供给

    string public name;   // 名称
    string public symbol;  // 代号
	uint8 public decimals = 18; // 小数位数
        constructor(string memory name_, string memory symbol_){
            name = name_;
            symbol = symbol_;
        }

        function transfer(address recipient, uint amount) public override returns (bool) {
            balanceOf[msg.sender] -= amount;
            balanceOf[recipient] += amount;
            emit Transfer(msg.sender, recipient, amount);
            return true;
        }
        function approve(address spender, uint amount) public override returns (bool) {
            allowance[msg.sender][spender] = amount;
            emit Approval(msg.sender, spender, amount);
            return true;
        }

        function transferFrom(
            address sender,
            address recipient,
            uint amount
            ) public override 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);
        }
    }

IERC20.sol

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

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the value of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 value) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 value) external returns (bool);
}