【Lua】题目小练9

题目：实现一个简单的"银行账户"类

要求：

使用元表模拟面向对象。
支持以下功能：
- Account:new(owner, balance) 创建账户（初始余额可选，默认为 0）。
- deposit(amount) 存款（不能为负数）。
- withdraw(amount) 取款（余额不足时拒绝取款）。
- getBalance() 查看余额。
所有金额操作必须保留两位小数（比如 100.567 存款后变成 100.57）。
加分项：实现两个账户之间的转账方法 transfer(toAccount, amount)。

Lua 复制代码

local Account = {}
Account.__index = Account

local function RoundBalance(balance)
    return math.floor(balance * 100 + 0.5) / 100
end

function Account:new(owner, balance)
    local obj = {
        owner = owner or "Alice",
        balance = (type(balance) == "number") and balance > 0 and RoundBalance(balance) or 0
    }
    setmetatable(obj, Account)
    return obj
end

function Account:deposit(amount)
    if type(amount) == "number" and amount >= 0 then
        self.balance = RoundBalance(self.balance + amount)
        print(tostring(self.owner) .. "存款")
    end
end

function Account:withdraw(amount)
    if type(amount) == "number" and amount >= 0 and self.balance >= amount then
        self.balance = RoundBalance(self.balance - amount)
        print(tostring(self.owner) .. "取款")
    end
end

function Account:getBalance()
    return self.balance
end

function Account:transfer(toAccount, amount)
    if type(toAccount) == "table" and type(amount) == "number" and amount >= 0 and self.balance >= amount then 
        self.balance = RoundBalance(self.balance - amount)
        toAccount.balance = RoundBalance(toAccount.balance + amount)
        print("成功转账给" .. tostring(toAccount.owner) .. "：".. amount)
    end
end

local a = Account:new("Alice", 100)
local b = Account:new("Bob")

a:deposit(50.456)       -- Alice 存款
a:withdraw(30)          -- Alice 取款
a:transfer(b, 50)       -- 转账给 Bob
print("Alice 余额:", a:getBalance()) -- 70.46
print("Bob 余额:", b:getBalance())   -- 50.00