更改 IF 循环内的变量值答案

【问题标题】：changing variable value inside IF loop更改 IF 循环内的变量值
【发布时间】：2020-10-23 21:56:57
【问题描述】：

我有一个接受值 1-5 的函数，我想声明一个名为“Des”的全局变量，并根据所选选项对其进行更改，因为我想在另一个函数中使用该值。我试过了，但它不起作用。

def mainNJ():
    #S_menu()
    print( "\033[1m" " PLEASE SELECT THE TYPE OF DONATION.")
    global Des
    validate = False
    while not validate:
        option = input(" INPUT VALUE 1 TO 5 : " "\033[0m")

    # For Selection 1 Animal Protection And Welfare.
        if option == str(1):
            validate = True
            print()
            print("\033[1m" " Animal Protection And Welfare Has Been Selected." "\033[0m")
            #Amount()
            Des1 = " Animal Protection And Welfare Has Been Selected."
            Des = Des1

    # For Selection 2 Support For Natural Disaster.
        elif option == str(2):
            validate = True
            print()
            print("\033[1m" " Support For Natural Disaster Has Been Selected." "\033[0m")
            #Amount()
            Des2 = " Support For Natural Disaster Has Been Selected."
            Des = Des2
    # For Selection 3 Children Education And Activities.
        elif option == str(3):
            validate = True
            print()
            print("\033[1m" " Children Education And Activities Has Been Selected." "\033[0m")
            #Amount()
            Des3 = " Children Education And Activities Has Been Selected."
            Des = Des3
    # For Selection 4 Children Education And Activities.
        elif option == str(4):
            validate = True
            print()
            print("\033[1m" " Caregiving And Health Research Has Been Selected." "\033[0m")
            #Amount()
            Des4 = " Caregiving And Health Research Has Been Selected."
            Des = Des4
    # For Selection 5 Conservation Of Cultural Arts.
        elif option == str(5):
            validate = True
            print()
            print("\033[1m" " Conservation Of Cultural Arts Has Been Selected." "\033[0m")
            #Amount()
            Des5 = " Conservation Of Cultural Arts Has Been Selected."
            Des = Des5

        else:
            print()
            print(" Invalid Option. Please Try Again.")
            #S_menu()

【问题讨论】：

对 Amount 和 S_Menu 的调用是否与问题相关？如果没有，您可能希望将它们从您的代码中删除，因为它们会阻止其他人按原样运行它。
@Roy2012 注意，我已将它们注释掉。
用类代替全局变量怎么样？
为什么您认为您的代码不起作用？ Des 在您的代码末尾分配了一个值。
作为一名程序员，你应该非常、非常、非常努力不使用全局变量。

标签： python python-3.x loops if-statement

【解决方案1】：

也许，如果 Des 没有在函数之外定义，你试图在它被分配之前访问它 > >。也就是说，在调用 mainNJ() 之前，你正在对 Des 做一些事情

如果这是问题，请给出解决方案

在你使用它的另一个函数中

try:
    print(Des) # example of usage
except NameError: 
    print("Des not yet created")
    # also you can put return statement so function does not continue
    # or call mainNJ() here

【讨论】：

【解决方案2】：

您将 Des 分配给 Desx，这是一个字符串。您需要将其分配给 int(option)

【讨论】：