python – while循环检查有效的用户输入？

发布时间：2020-12-20 11:43:00 所属栏目：Python 来源：网络整理

导读：参见英文答案 Asking the user for input until they give a valid response????????????????????????????????????17个 Python新手在这里很抱歉我确定这是一个愚蠢的问题,但我似乎无法在一个教程中解决以下挑战,该教程要求我使用while循环来检查有效的用户输

参见英文答案 > Asking the user for input until they give a valid response????????????????????????????????????17个
Python新手在这里很抱歉我确定这是一个愚蠢的问题,但我似乎无法在一个教程中解决以下挑战,该教程要求我使用while循环来检查有效的用户输入.

(使用Python2.7)

这是我的代码,但它无法正常工作：

choice = raw_input('Enjoying the course? (y/n)')
student_surveyPromptOn = True
while student_surveyPromptOn:
    if choice != raw_input('Enjoying the course? (y/n)'):
        print("Sorry,I didn't catch that. Enter again: ")
    else:
        student_surveyPromptOn = False

以上打印到控制台：

Enjoying the course? (y/n) y
Enjoying the course? (y/n) n
Sorry,I didn't catch that. Enter again: 
Enjoying the course? (y/n) x
Sorry,I didn't catch that. Enter again: 
Enjoying the course? (y/n)

这显然是不正确的 – 当用户输入’y’或’n’时循环应该结束但我不知道如何做到这一点.我在这做错了什么？

注意：挑战要求我同时使用！=运算符和loop_condition

解决方法

更短的解决方案

while raw_input("Enjoying the course? (y/n) ") not in ('y','n'):
    print("Sorry,I didn't catch that. Enter again:")

你的代码做错了什么

关于您的代码,您可以添加一些打印如下：

choice = raw_input("Enjoying the course? (y/n) ")
print("choice = " + choice)
student_surveyPromptOn = True
while student_surveyPromptOn:
    input = raw_input("Enjoying the course? (y/n) ")
    print("input = " + input)
    if choice != input:
        print("Sorry,I didn't catch that. Enter again:")
    else:
        student_surveyPromptOn = False

以上打印出：

Enjoying the course? (y/n) y
choice = y
Enjoying the course? (y/n) n
choice = y
input = n
Sorry,I didn't catch that. Enter again:
Enjoying the course? (y/n) x
choice = y
input = x
Sorry,I didn't catch that. Enter again:
Enjoying the course? (y/n)

正如您所看到的,代码中的第一步是出现问题并且您的答案初始化了选择的值.这就是你做错了.

使用！=和loop_condition的解决方案

如果你必须使用！=运算符和loop_condition,那么你应该编码：

student_surveyPromptOn = True
while student_surveyPromptOn:
    choice = raw_input("Enjoying the course? (y/n) ")
    if choice != 'y' and choice != 'n':
        print("Sorry,I didn't catch that. Enter again:")
    else:
        student_surveyPromptOn = False

然而,在我看来,Cyber??的解决方案和我更短的解决方案都更优雅(即更加pythonic).

（编辑：李大同）

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