程序问题

Question

所以我创建了一个程序，询问用户他们想从他们的支票账户中提取多少钱。如果执行该程序，检查应减去提取的金额。但是当我使用 global 时，即使在 procedure.I 已经建立了所有变量

之后，它也没有改变变量的值

我的代码在这里：

checking = 10000
savings = 10000
user_ammount_w = 0
user_currency_w = ""
def withdraw_saving (amount, country):
    global checking
    if country == "HKD":
        if checking >= amount:
            checking = checking - amount
            print("The amount of money left in your checking is", checking)
        else:
            print("Your request of", "$"+ str(amount), country, "is greater than the amount in your 
            checking account this withdraw will not work")

user_choice = input("Welcome to the ATM. Type 1 for withdrawing")
    if user_choice == "1":
        user_currency_w= input("Which currency would you like to withdraw from. For testing purposes 
        its only HKD")
        user_amount_w= int(input("How much money do you want to withdraw"))
        withdraw_saving (user_ammount_w, user_currency_w)

Answer 1

当您再次递归调用您的函数时，您总是将要减去的金额传递为 0，就像您传递 user_ammount_w 一样，您将其全局设置为 0。相反，我怀疑你想传入 user_amount_w 这是你用来捕获用户输入的变量名。

checking = 10000
savings = 10000
user_ammount_w = 0   #<----this is the value you passing to your function
user_currency_w = ""
def withdraw_saving (amount, country):
    global checking
    if country == "HKD":
        if checking >= amount:
            checking = checking - amount
            print("The amount of money left in your checking is", checking)
        else:
            print("Your request of", "$"+ str(amount), country, "is greater than the amount in your checking account this withdraw will not work")

    user_choice = input("Welcome to the ATM. Type 1 for withdrawing")
    if user_choice == "1":
        user_currency_w= input("Which currency would you like to withdraw from. For testing purposes its only HKD")
        user_amount_w= int(input("How much money do you want to withdraw")) #<--you never pass this value.
        withdraw_saving (user_ammount_w, user_currency_w)

withdraw_saving(20, 'HKD')

然而，使用全局变量并不是一个好主意，可能有更好的设计方法。

程序问题

Procedure issues

python

variables

error-handling

procedure