While loop with strings in python not behaving as expected

Question

I'm new to Python and I'm learning about loops and conditions. I have the code:

import random
import sys
import os

test_file = open("test.txt", "wb") #use wb if write

append = ""
while append != "exit":
    print("Write something to append to file: ")
    append = sys.stdin.readline()
    test_file.write(bytes(append, 'UTF-8'))

test_file.close()

Now, whenever I type in 'exit', I would expect it to exit out of the loop, but for some reason, it doesn't. It continues to be what seems like an infinite loop. What could be the reason behind it? Thanks in advance.

OneCricketeer · Accepted Answer · 2017-09-26 05:22:22Z

2

readline() includes the \n newline character.

You could use append.strip().

In [1]: import sys

In [2]: append = sys.stdin.readline()
test

In [3]: append
Out[3]: 'test\n'

In [4]: append.strip()
Out[4]: 'test'

or you could write that like this

with open("test.txt", "w") as test_file:
    while True:
        print("Write something to append to file: ")
        append = input()
        if len(append) == 0 or input.strip() == "exit":
            break   
        test_file.write(append)

answered Sep 26, 2017 at 5:22

OneCricketeer

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Comments

Van Peer · Accepted Answer · 2017-09-26 05:23:11Z

1

Change condition to "exit\n" and execute. It worked for me.

answered Sep 26, 2017 at 5:23

Van Peer

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Comments

jath03 · Accepted Answer · 2017-09-26 05:21:09Z

0

try printing append to see exactly what it is, or using append = str(sys.stdin.readline())

answered Sep 26, 2017 at 5:21

jath03

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