[英]"else" option alternative is ignored in a while loop
This is probably a simple problem that requires a simple answer...but I have been scratching my head why this happens.这可能是一个简单的问题,需要一个简单的答案……但我一直在摸索为什么会这样。 It's a problem on the loop that I am testing.这是我正在测试的循环上的一个问题。 Here's the loop:这是循环:
done = False
while done==False:
checkUser = input("Do you want to continue?\nType Y or y to continue; any other char to quit\nType here: ")
print(checkUser) # just to check the input
if checkUser =='Y' or 'y':
print ('Yes, I want to continue.')
done = False
break
else:
print('No. I want to quit now.')
done = True
sys.exit()
When I run this script on PyCharm, I get the outputs below:当我在 PyCharm 上运行此脚本时,我得到以下输出:
Do you want to continue?
Type Y or y to continue; any other char to quit
Type here: y
y
Yes, I want to continue
Do you want to continue?
Type Y or y to continue; any other char to quit
Type here: n
n
Yes, I want to continue
Question: why is the "else" option ignored?问题:为什么忽略“else”选项?
I tried so many variations like removing sys.exit()
and so forth, but the loop still behaves the same way.我尝试了很多变体,例如删除sys.exit()
等等,但循环的行为仍然相同。
change the line if checkUser =='Y' or 'y':
to if checkUser =='Y' or checkUser == 'y':
code worked as your expectation.将if checkUser =='Y' or 'y':
更改为if checkUser =='Y' or checkUser == 'y':
代码按您的预期工作。 if checkUser =='Y' or 'y':
means check if checkUser is 'Y' or 'y' is true which is true for any input. if checkUser =='Y' or 'y':
表示检查 checkUser 是否为 'Y' 或 'y' 是否为真,这对于任何输入都是正确的。
It's not necessary to add break
at the end of the if-condition as the while loop is already controlled by done
variable.没有必要在 if 条件的末尾添加break
,因为 while 循环已经由done
变量控制。 And your if-condition is not written properly such that the machine interprets as:并且您的 if 条件未正确编写,因此机器将解释为:
if (checkUser == 'Y') or ('y')
so the conditions become:所以条件变成:
condition_1: checkUser = 'Y'?
condition_2: 'y'?
if 'y' will always generate true so the while loop will go forever. if 'y' 将始终生成 true,因此 while 循环将永远是 go。 You should do:你应该做:
if checkUser == 'Y' or checkUser == 'y'
see if it helps you.看看它是否对你有帮助。
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