Is there any way to access the result something never assigned?

Question

while int(input("choose a number")) != 5 :

Say I wanted to see what number was input. Is there an indirect way to get at that?

EDIT Im probably not being very clear lol. . I know that in the debugger, you can step through and see what number gets input. Is there maybe a memory hack or something like it that lets you get at 'old' data after the fact?

If you didn't assign it to anything, there's no way to refer to it. — Mike Christensen, Jul 19 '13 at 17:03
So If i understand your question, you want to reference `input` after the while loop? — , Jul 19 '13 at 17:04
yeah, just currious if its possible. Not worried about it being correct or a good way, just if its even possible. — jason, Jul 19 '13 at 17:12
@jason Both of the answers provided are correct and do work, but Jon Clements answer is more efficient and less code. But Stephens answer is easier to read. — , Jul 19 '13 at 17:25

score 7 · Accepted Answer · answered Jul 19 '13 at 17:05

7

Nope - you have to assign it... Your example could be written using the two-argument style iter though:

for number in iter(lambda: int(input('Choose a number: ')), 5):
    print number # prints it if it wasn't 5...

answered Jul 19 '13 at 17:05

Jon Clements

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Nice! That was quick. – Jul 19 '13 at 17:05
marked as the answer because it answered the question plus forced me to research wtf a lambda was. – jason Jul 19 '13 at 19:16

rnbguy · Answer 2 · 2013-07-19T17:31:32.277

2

Do something like this. You don't have to assign, but just make up an additional function and use it every time you need to do this. Hope this helps.

def printAndReturn(x): print(x); return(x)

while printAndReturn(int(input("choose a number"))) != 5 :
      # do your stuff

edited Jul 19 '13 at 17:31

answered Jul 19 '13 at 17:25

rnbguy

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Stephan · Answer 3 · 2013-07-19T18:40:21.033

1

No, there is no way to access that input the way you did it, you would have had to store it. Here's a "hello world" level example

val = int(input("choose a number"))
while val != 5 :
  val = int(input("choose a number"))

edited Jul 19 '13 at 18:40

answered Jul 19 '13 at 17:20

Stephan

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score 1 · Answer 4 · edited May 23 '17 at 12:03

1

Semi-related hacky solution that technically answers your question but not really:

If you run this in the interactive python environment (the thing with the >>>), you can do this

>>>while int(input("choose a number: ")) != 5 :
...  print _
...
choose a number: 2
2
choose a number: 5
>>>

Note that this only works in the interactive environment.

edited May 23 '17 at 12:03

Community

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answered Jul 19 '13 at 18:27

Stephan

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score 0 · Answer 5 · answered Jun 24 '21 at 14:01

Not simply. If you attempt to read past values from stdin it'll give you an UnsupportedOperation exception. You could wrap stdin with a custom file buffer object that reads stdin when you want it and lets you seek.

import sys
from io import StringIO


class InputHistoryBuffer(StringIO):
    def __init__(self):
        super().__init__()
        self._stdin = sys.stdin
        sys.stdin = self

    def readline(self) -> str:
        value = self._stdin.readline()
        self.writelines([value])
        return value


input_history = InputHistoryBuffer()
x = input(":")

sys.stdin.seek(0)
print(sys.stdin.read(len(x)))

Is there any way to access the result something never assigned?

5 Answers5