Inputs via Python 3's input() being automatically converted to integers

Question

I'm reading in a text file using the command line via input() in Python 3, and lines in the file that appear numerical are being automatically treated as integers, causing errors. My understanding is that input() is not supposed to do any evaluation, and should treat these as strings. What is causing this behavior and how do I prevent it?

EDIT: For a cleaner example, if my code instead simply reads

cases = input()
print(type(cases))

My input file reads:

100
4 2

And I type into cmd:

script.py < input_file.txt > output_file.txt

My output file will contain

<type 'int'>

You are using python 2. See [how-do-i-detect-the-python-version-at-runtime](https://stackoverflow.com/questions/9079036/how-do-i-detect-the-python-version-at-runtime) — Patrick Artner, Apr 02 '19 at 19:38
Ah, Patrick, you're right. I thought that couldn't be the case because it still printed using the python 3 print. Thanks and solved! — ZWarner, Apr 02 '19 at 19:45
`print()` is still valid in Python2. Just `(type(cases))` is the same as `type(cases)` — OneCricketeer, Apr 02 '19 at 19:46

B. Shefter · Answer 1 · 2019-04-02T22:30:04.030

0

@Patrick Artner is almost certainly correct. Your code should perform as expected in Python 3, but in Python 2 you'd get the result you're seeing instead.

The Python 2 equivalent of Python 3's input() is raw_input(), which converts the input to a string as you expect.

EDIT: By the way, never ever use input() in Python 2. It evalutes the user's input, and therefore is unsafe. (What if the input were os.system("<some really horrible command>")?) That's why Python 3 replaced it.

edited Apr 02 '19 at 22:30

answered Apr 02 '19 at 19:44

B. Shefter

877
7
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Seriously, don't even write that. You'll be amazed by the amount of people who will try that out. – juanpa.arrivillaga Apr 02 '19 at 20:09

Inputs via Python 3's input() being automatically converted to integers

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