名称错误：未定义全局名称“PIN”

Question

我收到以下错误消息：

Traceback (most recent call last):
 File "/Volumes/KINGSTON/Programming/Assignment.py", line 17, in <module>
    Assignment()
 File "/Volumes/KINGSTON/Programming/Assignment.py", line 3, in Assignment

我的代码是： 在

^{pr2}$

如果有人知道我的错误并能解释，我将非常感谢你的帮助

Answer 1

引发这个特定的错误是因为当您说result = PIN，PIN实际上并不存在。因为它不在引号中，所以Python假设它是一个变量名，但是当它去检查这个变量是什么时，它找不到任何东西，并引发NameError。当您修复这个问题时，prompt也会发生这种情况，因为您稍后将其称为Prompt。在

我不确定这是否是您的完整代码，所以我不确定其他问题可能是什么，但看起来您似乎正在使用result和{}来控制while循环。请记住，while循环会一直运行，直到它所检查的条件是False（或者如果您手动打破它），那么您可以从以下内容开始，而不是声明额外的变量：

def Assignment():
    # No need to declare the other variables as they are only used once
    tries = 2

    # Go until tries == 0
    while tries > 0:
        ok = raw_input('What is your PIN?')
        # Remember that the output of `raw_input` is a string, so either make your
        # comparison value a string or your raw_input an int (here, 1234 is a string)
        if ok == '1234':
            # Here is another spot where you may hit an error if menu doesn't exist
            result = menu
            # Assuming that you can exit now, you use break
            break
        else:
            print 'Incorrect, please try again'
            # Little shortcut - you can rewrite tries = tries - 1 like this
            tries -= 1

        # I'll leave this for you to sort out, but do you want to show them both
        # the 'Please try again' and the 'Maximum attempts' messages?
        if tries == 0:
            print 'You have used your maximum number of attempts. Goodbye.'