1.12 Receive 收學費

Receive

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract TuitionPayment {
    address public school;
    uint public tuitionFee;
    mapping(address => uint) public studentBalances;

    event TuitionReceived(address payer, uint amount);

    constructor(uint _tuitionFee) {
        school = msg.sender;
        tuitionFee = _tuitionFee;
    }

    // 定義 receive 函式來接收學費
    receive() external payable {
        require(msg.sender != school, "School cannot pay tuition");
        require(msg.value == tuitionFee, "Incorrect tuition fee amount");

        studentBalances[msg.sender] += msg.value;
        emit TuitionReceived(msg.sender, msg.value);
    }

    // 提取合約中的以太幣
    function withdraw(uint amount) public {
        require(msg.sender == school, "Only school can withdraw");
        require(amount <= address(this).balance, "Insufficient balance");

        payable(school).transfer(amount);
    }
}

• 當我們想要在 Solidity 合約中接收以太幣，例如收取學費，可以使用 receive 函式來實現這一功能。
• TuitionPayment 合約用於收取學費。在合約創建時，設定了學校的地址和學費的金額。
• receive 函式被定義為外部函式，用於接收以太幣。
• 當有人向合約地址轉帳時，如果轉帳金額等於學費金額，則該函式將被自動調用。
• 如果轉帳者不是學校，且轉帳金額正確，則學費將被記錄到相應的學生帳戶中。
• 當學費被成功接收時，將觸發一個事件 TuitionReceived，用於通知外部觀察者。
• 合約還包含一個 withdraw 函式，用於將合約中的以太幣提取到學校地址。