求助。不知以下代码有什么错误？

Question

class BankAccount:     def __init__(self, acct_number, acct_name):         self.acct_number = acct_number         self.acct_name = acct_name         self.balance = 0.0              def displayBalance(self):         print "The account balance is:", self.balance          def deposit(self, amount):         self.balance = self.balance + amount         print "You deposited", amount         print "The new balance is:", self.balance              def withdraw(self, amount):         if self.balance >= amount:             self.balance = self.balance - amount             print "You withdrew", amount             print "The new balance is:", self.balance         else:             print "You tried to withdraw", amount             print "The account balance is:", self.balance             print "Withdrawal denied. Not enough funds." class InterestAccount(BankAccount): def addInterest(self, rate): interest = self.balance * rate print "adding interest to the account,", rate * 100,"percent" self.deposit (interest) myAccount = BankAccount(234, "Warren Sande") print "Account name:",myAccount.acct_name print "Account number:", myAccount.acct_number myAccount.displayBalance() myAccount.deposit(34.52) myAccount.addInterest(0.11)运行时提示：Traceback (most recent call last):  File "D:\Workspaces\MyEclipse Professional 2014\NO1\helloworld\__init__.py", line 46, in <module>    myAccount.addInterest(0.11)AttributeError: BankAccount instance has no attribute 'addInterest'不知为何出错，请指教。

Answer 1

myAccount下没有'addInterest'属性，报错也是这个意思，你漏写了一句。

class BankAccount:
    def __init__(self, acct_number, acct_name):
        self.acct_number = acct_number
        self.acct_name = acct_name
        self.balance = 0.0
         
    def displayBalance(self):
        print "The account balance is:", self.balance
     
    def deposit(self, amount):
        self.balance = self.balance + amount
        print "You deposited", amount
        print "The new balance is:", self.balance
         
    def withdraw(self, amount):
        if self.balance >= amount:
            self.balance = self.balance - amount
            print "You withdrew", amount
            print "The new balance is:", self.balance
        else:
            print "You tried to withdraw", amount
            print "The account balance is:", self.balance
            print "Withdrawal denied. Not enough funds."
 
class InterestAccount(BankAccount):
    def addInterest(self, rate):
        interest = self.balance * rate
        print "adding interest to the account,", rate * 100,"percent"
        self.deposit (interest)

myAccount = InterestAccount(234, "Warren Sande") #看这里
# myAccount = BankAccount(234, "Warren Sande")
print "Account name:",myAccount.acct_name
print "Account number:", myAccount.acct_number
myAccount.displayBalance()
myAccount.deposit(34.52)
myAccount.addInterest(0.11)

Answer 2

InterestAccount继承BankAccount,也就是InterestAccount有BankAccount的所有方法和属性,反过来BankAccount是没有InterestAccount的属性和方法的,你声明的是BankAccount,所以没有addInterest这个方法了.你要声明InterestAccount才行

Answer 3

AttributeError: BankAccount instance has no attribute 'addInterest'

说没有这个法属性，看看有没有'addInterest'，从你的代码里我没找到，可能是你漏写了。