input() vs sys.stdin.read()

Question

import sys
s1 = input()
s2 = sys.stdin.read(1)

#type "s" for example

s1 == "s" #False
s2 == "s" #True

Why? How can I make input() to work properly? I tried to encode/decode s1, but it doesn't work.

Thank you.

Solution 1

If you're on Windows, you'll notice that the result of input() when you type an 's' and Enter is "s\r". Strip all trailing whitespace from the result and you'll be fine.

Solution 2

You didn't say which version of Python you are using, so I'm going to guess you were using Python 3.2 running on Microsoft Windows.

This is a known bug see http://bugs.python.org/issue11272 "input() has trailing carriage return on windows"

Workarounds would include using a different version of Python, using an operating system that isn't windows, or stripping trailing carriage returns off any string() returned from input(). You should also be aware that iterating over stdin has the same problem.

Comments

[fogbit]

Yes, it's version 3.2 on windows. Thank you for explanation. Problem solved.

[Duncan]

On the 'use a different version of Python' suggestion, I see that Python 3.2.1rc1 has been released, so if you don't mind using a release candidate for a minor point fix you can just upgrade to that version and the issue is fixed. See python.org/download/releases/3.2.1

[Duncan]

Note that when commenting on my answer @fogbit confirmed they are using Python 3.2 where input() is the correct thing to use. Your advice would only apply for earlier versions of Python.

[FlaPer87]

You're right. When I posted my answer I didn't know the python version. I should've asked. Thanks ^^