（关闭）赋值前引用的局部变量“exit”？

Question

我正在Wing IDE上运行python2.75

代码：

exit = False

while not exit:

    selection = int(raw_input("Press 1 to go and 0 to quit: ")
    if selection == 1:
       print("yay")
    elif selection == 0:
       print("Goodbye")
       exit = True
    else:
       print("Go away")

当我按0时，它说：

local variable 'exit' referenced before assignment

怎么了？你知道吗

Answer 1

您的代码工作正常，如下所示：

exit = False

while not exit:
    selection = int(raw_input("Press 1 to go and 0 to quit: "))       #added ) to correct syntax error
    if selection == 1:
        print("yay")
    elif selection == 0:
        print("Goodbye")
        exit = True
    else:
        print("Go away")

DEMO

Answer 2

你的int（）缺少一个很接近的paren

不过，如果您使用的是while循环，为什么不简单地使用break而不是boolean呢？它干净多了。只需键入break，循环就结束了，而不是exit=True。你知道吗

如果我对您键入内容的理解是正确的，您希望最后得到：

    while True:
      selection = int(raw_input("Press 1 to go and 0 to quit: "))
      if selection == 1:
        print("yay")
      elif selection == 0:
        print("Goodbye")
        break
      else:
        print("Go away")