Question

我正在完成这项家庭作业，我坚持认为这是一个非常简单的问题。代码的前提是一个小额现金系统，用户可以在其中存款，取款和获得当前余额。我的问题是提款和存款似乎没有通过我的账户类。这是全局变量问题吗？我稍后会添加时间戳。提前谢谢。

import datetime
import time

class Account:
    def __init__(self, initial):
        self.balance = initial

    def deposit(self, amt):
        self.balance = self.balance + amt

    def withdraw(self,amt):
        self.balance = self.balance - amt

    def getbalance(self):
        return self.balance

def yesno(prompt): 
    ans = raw_input(prompt) 
    return (ans[0]=='y' or ans[0]=='Y')

def run():  
    done = 0   
    while not done: 
        user_options()
        print
        done = not yesno("Do another? ")
        print

def user_options():
    print ("Here are your options:")
    print
    print ("   (a) Deposit cash")
    print ("   (b) Withdraw cash")
    print ("   (c) Print Balance")
    print
    u = raw_input("Please select a letter option: ").lower()
    user_input(u)

def user_input(choice):
    account = Account(0.00)
    if choice == "a" or choice == "b" or choice == "c":

        if choice == "a":
            d = input("Enter Deposit Amount: $")
            account.deposit(d)

        if choice == "b":
            w = input ("Enter Withdraw Amount: $")
            account.withdraw(w)

        if choice == "c":
            print ("Balance Amount: $"),
            print account.getbalance()

    else:
        print ("Not a correct option")


run()

#now = datetime.datetime.now()

Python版本：2.7.2

Answer 1

问题是：

account = Account(0.00)

每次调用user_input时，您都会创建一个新的空帐户。由于user_input是从user_options调用的，它在运行中的while循环内调用，所以这发生在每次事务之前。

您需要将该行移出循环，例如：

def run():
    done = 0
    global account # just showing you one way, not recommending this
    account = Account(0.00)
    while not done:
        user_options()
        print
        done = not yesno("Do another? ")
        print

Answer 2

您不需要全局变量，只需稍微重构代码

def run():  
    account = Account(0.00)
    done = 0   
    while not done: 
        user_option = user_options()
        user_input(user_option, account)

        print
        done = not yesno("Do another? ")
        print

def user_options():
    print ("Here are your options:")
    print
    print ("   (a) Deposit cash")
    print ("   (b) Withdraw cash")
    print ("   (c) Print Balance")
    print
    return raw_input("Please select a letter option: ").lower()

def user_input(choice, account):
    if choice == "a" or choice == "b" or choice == "c":

        if choice == "a":
            d = input("Enter Deposit Amount: $")
            account.deposit(d)

        if choice == "b":
            w = input ("Enter Withdraw Amount: $")
            account.withdraw(w)

        if choice == "c":
            print ("Balance Amount: $"),
            print account.getbalance()

    else:
        print ("Not a correct option")


run()

你仍然可以做更多的事情来使代码更好，这足以使帐户部分工作

可能的全局变量问题？

2 个答案: