Python 业余爱好者 - 'Greeting program' - 'Referenced before assignment error'

Question

正如我在上一个问题中所说，我是一名 Python 业余爱好者。我犯了几个愚蠢的错误。我正在尝试使用 Python 3.4 制作一个非常简单的问候语程序，但是我遇到了一个错误。我的错误是:

UnboundLocalError:赋值前引用局部变量“lastNameFunction”

这是我的代码(我知道我可能不需要全部发布，但代码不多):

def main():
import time 
running = True
while (running):
    firstNameInput = input("What is your first name?\n")
    firstName = firstNameInput.title()
    print ("You have entered '%s' as your first name. Is this correct?"%firstName)
    time.sleep (1)
    choice = input("Enter 'Y' for Yes or 'N' for No\n")
    if(choice.upper() == "Y"):
        lastNameFunction()
    elif(choice.upper() == "N"):
        main()

    def lastNameFunction():
        lastNameInput = input("Hi %s. Please enter your last name. \n"%firstName)
        lastName = lastNameInput.title() 
if __name__ == '__main__':
main()

我将不胜感激任何帮助和建议!请考虑到我对这些东西真的很陌生。我也不太确定在函数内部有一个函数，但我认为这将是一个修复，以便在输入“lastName”时可以使用“firstName”。

提前致谢! :)

Answer 1

在使用 lastNameFunction() 调用它之前，您需要将 lastNameFunction 声明移动到某处，例如:

def main():
    import time
    running = True
    while (running):
        firstNameInput = input("What is your first name?\n")
        firstName = firstNameInput.title()
        print ("You have entered '%s' as your first name. Is this correct?" % firstName)

        time.sleep (1)
        choice = input("Enter 'Y' for Yes or 'N' for No\n")

        def lastNameFunction():
            lastNameInput = input("Hi %s. Please enter your last name. \n" % firstName)
            lastName = lastNameInput.title()

        if(choice.upper() == "Y"):
            lastNameFunction()
        elif(choice.upper() == "N"):
            main()

if __name__ == '__main__':
    main()

您也可以将它移到 main 函数之外，但是您需要在使用函数参数时传递 firstName:

def lastNameFunction(firstName):
    lastNameInput = input("Hi %s. Please enter your last name. \n" % firstName)
    lastName = lastNameInput.title()

def main():
    ...
    lastNameFunction(firstName)
    ...