How to read user input until EOF in python?

Question

I came across this problem in UVa OJ. 272-Text Quotes

Well, the problem is quite trivial. But the thing is I am not able to read the input. The input is provided in the form of text lines and end of input is indicated by EOF. In C/C++ this can be done by running a while loop:

while( scanf("%s",&s)!=EOF ) { //do something }

How can this be done in python .?

I have searched the web but I did not find any satisfactory answer.

Note that the input must be read from the console and not from a file.

Possible duplicate of [How to read user input until EOF?](https://stackoverflow.com/questions/21235855/how-to-read-user-input-until-eof) — MrSeeker, Sep 01 '17 at 17:21

score 8 · Accepted Answer · edited Aug 25 '20 at 23:39

8

You can use sys module:

import sys

complete_input = sys.stdin.read()

sys.stdin is a file like object that you can treat like a Python File object.

From the documentation:

Help on built-in function read:

read(size=-1, /) method of _io.TextIOWrapper instance Read at most n characters from stream.
Read from underlying buffer until we have n characters or we hit EOF.
If n is negative or omitted, read until EOF.

edited Aug 25 '20 at 23:39

antoninkriz

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answered Sep 01 '17 at 15:38

What signals the input to terminate in this case then? Can u please see the input format given the problem [ link provided in the question]. I am not sure whether this works for this or not. Thanks – rohan Sep 01 '17 at 16:00
@rohan the EOF character, the same as C/C++ – Sep 01 '17 at 16:08

MrSeeker · Answer 2 · 2017-09-01T17:13:41.073

You can read input from console till the end of file using sys and os module in python. I have used these methods in online judges like SPOJ several times.

First method (recommened):

from sys import stdin

for line in stdin:
    if line == '': # If empty string is read then stop the loop
        break
    process(line) # perform some operation(s) on given string

Note that there will be an end-line character \n at the end of every line you read. If you want to avoid printing 2 end-line characters while printing line use print(line, end='').

Second method:

import os
# here 0 and 10**6 represents starting point and end point in bytes.
lines = os.read(0, 10**6).strip().splitlines() 
for x in lines:
    line = x.decode('utf-8') # convert bytes-like object to string
    print(line)

This method does not work on all online judges but it is the fastest way to read input from a file or console.

Third method:

while True:
    line = input()
    if line == '':
        break
    process(line)

replace input() with raw_input() if you're still using python 2.

A comparison between methods 1 and 2 in terms of their time taken to read the input will make things clear. ..? — rohan, Sep 02 '17 at 04:49

score 5 · Answer 3 · answered Aug 30 '20 at 07:15

5

For HackerRank and HackerEarth platform below implementation is preferred:

while True:
try :
    line = input()
    ...
except EOFError:
    break;

answered Aug 30 '20 at 07:15

khush

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score 3 · Answer 4 · answered Jun 30 '20 at 14:42

3

This how you can do it :

while True:
   try :
      line = input()
      ...
   except EOFError:
      pass

answered Jun 30 '20 at 14:42

soufiane yes

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3

score 1 · Answer 5 · answered Sep 01 '17 at 15:46

1

If you need to read one character on the keyboard at a time, you can see an implementation of getch in Python: Python read a single character from the user

answered Sep 01 '17 at 15:46

Laurent LAPORTE

21,958
6
58
103

1

Thanks for this idea. This can be done certainly but this will cause the problem solution to include a whole module just to read input. which will not be very efficient bearing in mind that this is a constrained problem. – rohan Sep 01 '17 at 16:07

How to read user input until EOF in python?

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