Question

python中类继承的问题，很简单的代码，求大神帮小弟答疑一下，真心感谢，在线等。

class BankAccount:
def __init__(self,name,account):
self.name=name
self.account=account
self.balance=0.0
print 'Welcome!',name,account
def displaybalance(self):
print 'Your balance is',self.balance
def save(self,money):
self.balance=self.balance+money
print 'You have save',money,'to your account.'
self.displaybalance()
def take(self,money):
if self.balance>=money:
self.balance=self.balance-money
print 'You have take',money,'from your account.'
self.displaybalance()
else:
print 'You will take '+str(money)+',but your account has not enough money to take.'
print 'Your account only has',self.balance

class InterestAccount(BankAccount):
def add_interest(self,interest_rate,time):
for i in range(time):
interest=self.balance*interest_rate
self.balance=self.balance+interest
print 'You have saved for',time,'years.'
print 'Add interest to your account:'+'('+str(self.account)+')',interest_rate*100,'percent'
print 'Now your balance is:',self.balance

YQaccount=InterestAccount('YQ',18695997416)
YQaccount.save(450000)
YQaccount.add_interest(0.03,5)
YQaccount.take(200000)
YQaccount.add_interest(0.03,5)
这个代码没有任何错误，我想问一下为什么下面那个子类继承了上面的父类，但是没有写出继承属性的代码如BankAccount.__init__(self,name,account)，却可以继承父类属性中的name和account而self.balance却不归零？

Answer 1

因为子类没有自己的__init__方法，它的__init__方法是直接继承父类的，初始化时就会执行父类的__init__方法。
如果子类自己有__init__方法，才必须在子类的__init__方法中显式调用BankAccount.__init__(self,name,account)