Python script not running until i hit ctrl+C

Question

I have written a simple Python3 program like below:

import sys
input = sys.stdin.read()
tokens = input.split()
print (tokens)
a = int(tokens[0])
b = int(tokens[1])
if ((a + b)> 18):
    print ("Input numbers should be between 0 and 9")
else:
    print(a + b)

but while running this like below:

C:\Python_Class>python APlusB.py
3 5<- pressed enter after this

but output is not coming until I hit ctrl+C (in windows)

C:\Python_Class>python APlusB.py
3 5
['3', '5']
8
Traceback (most recent call last):
  File "APlusB.py", line 20, in <module>
    print(a + b)
KeyboardInterrupt

use the input function.

juanpa.arrivillaga
– juanpa.arrivillaga

2016-11-06 18:00:53 +00:00
Commented Nov 6, 2016 at 18:00 — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Nov 6, 2016 at 18:00

DaoWen · Accepted Answer · 2016-11-06 18:01:59Z

2

sys.stdin.read() will read until an EOF (end of file) is encountered. That's why "pressing enter" doesn't seem to do anything. You can send an EOF on Windows by typing Ctrl+Z, or on *nix systems with Ctrl+D.

(Note that you probably still need to hit Enter before hitting Ctrl+Z. I don't think the terminal treats the EOF correctly if it's not at the start of a line.)

If you just want to read input until a newline, use input() instead of sys.stdin.read().

answered Nov 6, 2016 at 18:01

DaoWen

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1 Comment

DaoWen Over a year ago

See this answer for a more detailed explanation about EOF behavior at the beginning of a new line vs other places in a line: stackoverflow.com/a/7373799/1427124

Community · Accepted Answer · 2020-06-20 09:12:55Z

0

you can read user's input using input() function.

Example Code

user_input = input("Please input a number !")
# Rest of the code

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Nov 6, 2016 at 18:05

Michael Yousrie

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Comments

ForceBru · Accepted Answer · 2016-11-06 18:08:06Z

0

This happens because sys.stdin.read attempts to read all the data that the standard input can provide, including new lines, spaces, tabs, whatever. It will stop reading only if the interpreter's interrupted or it hits an EndOfFile (Ctrl+D on UNIX-like systems and Ctrl+Z on Windows).

The standard function that asks for input is simply input()

edited Nov 6, 2016 at 18:08

answered Nov 6, 2016 at 18:02

ForceBru

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1 Comment

DaoWen Over a year ago

The OP specifically mentioned using Windows, in which case Ctrl+D most likely does not result in EOF.

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