while循环中的回溯(python 3.x)

Question

我是Python的新手。我想知道我是否可以使用输入并问一个类似“你确定吗？”这样的问题，如果答案是否定的，则返回到原始输入。到目前为止，我得到了这样的结论：

variable = input("Make a choice between a, b, c or d. ")
while variable not in ("a","b","c","d"):
    variable = input("Make a correct choice. ")

if variable == "a":
    do things
if variable == "b":
    do other things
etc etc

我想问一下，在他们输入了他们的选择之后，你确定你的选择吗？如果他们说是，那很好，继续，但如果他们说‘不’，我希望能够转到相同的输入，而不是再次键入整个内容。有没有办法做到这一点？

Answer 1

你可以将你想要重复的部分嵌入到你想要突破的while True块中吗？例如：

while True
    answer = input("What is the correct answer, a, b, or c? ")
    check = input("Are you sure (y/n)? ")
    if check=="y" or check=="Y":
        break

Answer 2

将您已有的代码包装在另一个while循环中：

# loop forever until they confirm their choice
while True:
    variable = input("Make a choice between a, b, c or d. ")
    while variable not in ("a","b","c","d"):
        variable = input("Make a correct choice. ")
    confirm = input("You entered %s.  Is this correct?" % variable)
    if confirm == "yes":
        break

Answer 3

像这样的东西将会工作(尽管它现在不是最干净的东西)。

def prompt_for_something():
   variable = input("Make a choice between a, b, c or d. ")
   while variable not in ("a","b","c","d"):
       variable = input("Make a correct choice. ")

   confirm = input("Are you sure?")

   if confirm == "No": return False
   return variable

option = prompt_for_something()
while option == False:
   option = prompt_for_something()

if option == "a":
   do something