Python raw_input 应该只接受单个字符
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raw_input should accept only single character
提问by MBanerjee
Possible Duplicate:
Python read a single character from the user
可能的重复：
Python 从用户读取单个字符
I am using below code.But instead of accepting a single character its allowing user to put more than a single character.
我正在使用下面的代码。但是它不接受单个字符，而是允许用户输入多个字符。
How can I fix that?
我该如何解决？
guess = raw_input(':')
guessInLower = guess.lower()
采纳答案by Matt
The following will continuously prompt the user for input until they enter exactly one character.
以下内容将不断提示用户输入，直到他们输入了一个字符。
userInput = ''
while len(userInput) != 1:
userInput = raw_input(':')
guessInLower = userInput.lower()
This does the same, but also informs them of the one character limit before prompting again for input
这样做是一样的，但还会在再次提示输入之前通知他们一个字符的限制
while True:
userInput = raw_input(':')
if len(userInput) == 1:
break
print 'Please enter only one character'
guessInLower = userInput.lower()
It looks like you are expecting only letters. If that is the case you can expand this further to require that:
看起来你只期待字母。如果是这种情况，您可以进一步扩展以要求：
import string
while True:
userInput = raw_input(':')
if len(userInput) == 1:
if userInput in string.letters:
break
print 'Please enter only letters'
else:
print 'Please enter only one character'
guessInLower = userInput.lower()
回答by pwaller
By default python uses line-buffered input, which means that the raw_input()call will not return until the user hits enter. If you want to turn off the line buffering, you may have to look at OS-specific things you can do. You can find a recipe demonstrating this here.
默认情况下，python 使用行缓冲输入，这意味着raw_input()在用户按下 Enter 之前调用不会返回。如果您想关闭行缓冲，您可能需要查看您可以执行的特定于操作系统的操作。您可以在此处找到演示此方法的食谱。
回答by Matt
For Python 2.7.x,
对于 Python 2.7.x，
guess = raw_input(': ')[0].lower()
For Python 3.x
对于 Python 3.x
guess = input (': ')[0].lower()
in both cases, the first character from the terminal raw input string (no need for using '') will be lowered and passed by to the variable guess.
在这两种情况下，终端原始输入字符串中的第一个字符（不需要使用''）将被降低并传递给变量guess。
