How to read input() from a text file in Python

Question

My Python program requests some user input:

n = int(input())
for i in range(n):
    s = input()
    # ...

For debugging purposes, I would like to create a test input.txt file like this:

3
string1
string2
string3

so that I need not to manually enter data from the keyboard every time I launch it for debug.

Is there any way to get input() from text file, not from keyboard (without changing program code).

I am using Wing Personal as a dev tool.

Update

I know for sure, that there exist bots which are able to test python programs passing various inputs and comparing output with known answers. I guess these bots do not hit the keyboard with iron fingers. Maybe they use command-line tools to pass input.txt to the Python so that it reads input() from that file, not from keyboard. I would like to learn how to do it.

Gorock · Accepted Answer · 2019-12-03 14:50:15Z

23

Input reads from Standard input so if you use bash you can redirect stdin to a file

without changing your code

in bash you would run something like

cat textfile | programm.py

or

< textfile programm.py

answered Dec 3, 2019 at 14:50

Gorock

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4 Comments

DUDANF Over a year ago

OP asked for python?

Gorock Over a year ago

he also asks (without changing program code). so i provided a method for changing standard input without touching the code

DUDANF Over a year ago

standing your ground, I like it!

Zabir Al Nazi Nabil Over a year ago

I think you meant, cat textfile | python programm.py

George Ogden · Accepted Answer · 2021-09-12 18:50:44Z

10

I've noticed that none of these solutions redirects the stdin from Python. To do that, you can use this snippet:

import sys
sys.stdin = open('input.txt', 'r')

Hopefully, that helps you!

answered Sep 12, 2021 at 18:50

George Ogden

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Comments

Almog · Accepted Answer · 2019-12-03 14:43:21Z

1

You can read the file into a list like this:

 with open('filename.txt', 'r') as file:
     input_lines = [line.strip() for line in file]

s would be data in index i.

n = int(input())
for i in range(n):
    s = input_lines[i]
    # ...

Make sure your py file is in the same dir as your txt file.

answered Dec 3, 2019 at 14:43

Almog

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Comments

do thuan · Accepted Answer · 2019-12-03 15:07:42Z

0

You can create a test.py file which is used to run your test. In the test.py, you will read the content of input.txt and import the programming.

For example, in test.py file.

import main_code
with open('input.txt', 'r') as file:
   lines = file.readlines()

for line in lines:
   s = line

"""
working with the input.
"""

answered Dec 3, 2019 at 15:07

do thuan

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