尝试创建支票账户类但遇到问题

Question

编写一个名为“CheckingAccount”的类，其中包含当前 账户余额（int）和以下方法：

• init - 采用“balance”参数来初始化对象的数据（余额）。请记住，方法 init 实现为 ___init__.

• withdraw - 接受输入参数“amount”并通过减少余额来修改数据。如果“金额”导致透支，减去 额外的20美元。这个方法应该返回余额。

• deposit - 接受输入参数“amount”并通过将余额增加“amount”来修改数据。

我正在尝试解决上述问题，但我有点迷茫，这是我迄今为止最好的（今天更新了代码）：

# write your code here
class CheckingAccount:
    balance = 0
    amount = 0
    
    def __init__(self, balance = 0):
        self.balance = balance
        
    def withdraw(self, amount = 0):
        if self.amount > self.balance:
            self.balance -= 20
        else:
            self.balance -= 1
    def deposit(self, amount = 0):
        self.amount += amount
        return amount
        
an = CheckingAccount(80)
an.withdraw(40)
print("Your old balance was {}. Your new balance is now {}.".format(an.balance))

我越来越接近了，但我的旧余额显示为 79 而不是 80，而我的新余额显示为 0，而我认为我预期的是 40。我觉得我错过了一些东西。

Answer 1

class CheckingAccount:
    balance = 0
    oldbalance = 0
    #amount = 0
   
    def __init__(self, balance = 0):
        self.balance = balance
       
    def withdraw(self, amount = 0):
        self.oldbalance = self.balance
        if amount < self.balance:
            self.balance -= amount
            print("Amount withdrawn {}".format(amount))
        else:
            self.balance -= amount + 20
            print("Amount withdraw ${} with penalty of $20".format(amount))
        
    def deposit(self, amount = 0):
        self.oldbalance = self.balance
        self.balance += amount
        return amount
       
an = CheckingAccount(80)
an.withdraw(10)
print("Your old balance was {}. Your new balance is now {}.".format(an.oldbalance, an.balance))