如何永久存储用户输入以便将来添加到另一个变量？

Question

我正在尝试制作一个预算程序，我需要对其进行编程，以便每当我运行代码时我都可以将我那周赚的钱添加到总额中。我希望能够存储最新输入的金额pay_this_week并将其添加到total每次运行代码时。我应该制作pay_this_week一个列表并将其附加到总计中吗？这是代码：def money_earnt():    total = int()    while True:        try:            pay_this_week = int(input("How much money did you earn this week? "))            break        except ValueError:            print("Oops! That was no valid number. Try again...")    pay_this_week_message = "You've earnt £{0} this week!".format(pay_this_week)    total = pay_this_week + total    total_message = "You have earned £{0} in total!".format(total)    print(pay_this_week_message)    print(total_message)money_earnt()

Answer 1

当程序运行时，它们使用的任何变量都存储在内存中，每当您关闭程序时，内存就会丢失。如果您希望在运行程序时存储数据，则需要将它们保存到文件中。

幸运的是，Python 有一些非常有用的函数可以做到这一点。

您的代码看起来非常整洁并且可以正常工作，我们只需要添加文件读取和写入

首先，您需要使用读取模式打开我们用来存储总计的文件"r"

file = open("total.txt", "r") # open the file in read mode

data = file.readline() # read the line

total = int(data) # get the total as an int

然而，当你第一次运行程序时，这个文件还不存在（因为我们还没有创建它），总数将为 0。我们可以使用一个块try来捕获这个文件，并使用模式创建一个新文件"w+"，这将如果同名文件不存在则创建一个文件

total = int()

try: # try open the file

    file = open("total.txt", "r") 

    data = file.readline()

    total = int(data)

except: # if file does not exist

    file = open("total.txt", "w+") # create file

    total = 0 # this is the first time we run this so total is 0

file.close() # close file for now

然后你可以运行你的代码，在我们想要存储新的总计之后，这次以写入模式打开文件"w"，这将从文件中擦除旧的总计

file = open("total.txt", "w") # wipe the file and let us write to it

file.write(str(total)) # write the data

file.close() # close the file

现在，下次运行程序时，它将加载此总数并正确相加！

这就是全部内容，

def money_earnt():

    total = int()

    try: # try open the file

        file = open("total.txt", "r") 

        data = file.readline()

        total = int(data)

    except: # if file does not exist

        file = open("total.txt", "w+") # create file

        total = 0

    

    file.close() # close file for now

    while True:

        try:

            pay_this_week = int(input("How much money did you earn this week? "))

            break

        except ValueError:

            print("Oops! That was no valid number. Try again...")

    pay_this_week_message = "You've earnt £{0} this week!".format(pay_this_week)

    total = pay_this_week + total

    total_message = "You have earned £{0} in total!".format(total)

    print(pay_this_week_message)

    print(total_message)

    file = open("total.txt", "w") # wipe the file and let us write to it

    file.write(str(total)) # write the data

    file.close() # close the file

money_earnt()

Answer 2

你已经快到了，不要放弃。2个主要错误：

1. break如果while你想让它永远持续下去就没有必要

2. 在Python中，标识产生了所有的差异，只有标识的行才进入到while中，我猜你希望所有的行都在里面。

这是我的尝试：

    def money_earnt():

    total = int()

    while True:

        try:

            pay_this_week = int(input("How much money did you earn this week? "))

        except ValueError:

            print("Oops! That was no valid number. Try again...") 

            continue

        pay_this_week_message = "You've earnt £{0} this week!".format(pay_this_week)

    

        total = pay_this_week + total

    

        total_message = "You have earned £{0} in total!".format(total)

    

        print(pay_this_week_message)

        print(total_message)

   

money_earnt()

我的输出是：

How much money did you earn this week? 4

You've earnt £4 this week!

You have earned £4 in total!

How much money did you earn this week? 5

You've earnt £5 this week!

You have earned £9 in total!

How much money did you earn this week? 6

You've earnt £6 this week!

You have earned £15 in total!

How much money did you earn this week?