【新年企劃】來去自如跳來跳去的幣 | 智能合約開發計劃 #3

前言

第三個試作品 | 可交易的智能合約

《錢包餘額查詢》

mapping(address => uint256) public balanceOf;

《轉帳》

事件

event Transfer(address indexed from, address indexed to, uint256 value);

轉帳程式碼

function transfer(address _to, uint256 _value) external returns (bool success) {
        require(balanceOf[msg.sender] >= _value);
        require(_to != address(0));

        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;

        emit Transfer(msg.sender, _to, _value);
        return true;
}

角色定義

檢查機制－檢查匯款人餘額

require(balanceOf[msg.sender] >= _value);

檢查機制－檢查收款人地址正確性

require(_to != address(0));

If the target account is not set (the transaction does not have a recipient or the recipient is set to null), the transaction creates a new contract. As already mentioned, the address of that contract is not the zero address but an address derived from the sender and its number of transactions sent (the “nonce”).

轉帳流程

換款人錢包裡的錢 = 換款人錢包裡的錢 - 匯出的金額
收款人錢包裡的錢 = 收款人錢包裡的錢 + 收到的金額

balanceOf[msg.sender] = balanceOf[msg.sender] - _value;
balanceOf[_to] = balanceOf[_to] + _value;

balanceOf[msg.sender] -= _value;
balanceOf[_to] += _value;

發送交易

emit Transfer(msg.sender, _to, _value);
return true;

TransferToken.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.11;

contract Token {

    string public name;
    string public symbol;
    uint256 public decimals;
    uint256 public totalSupply;

    constructor(string memory _name, string memory _symbol, uint _decimals, uint _totalSupply){
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        totalSupply = _totalSupply;
        balanceOf[msg.sender] = totalSupply;
    }

    mapping(address => uint256) public balanceOf;

　　event Transfer(address indexed from, address indexed to, uint256 value);

    function transfer(address _to, uint256 _value) external returns(bool success){
        require(balanceOf[msg.sender] >= _value);
        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
    }
｝

在錢包之間走跳的錢

轉帳

驗證結果

結語

延伸閱讀