Python printing inline with a sleep command

Question

Why is the following code

from __future__ import print_function
from time import sleep

def print_inline():
    print("Hello ", end='')
    sleep(5)
    print("World")

print_inline()

waits until the sleep is done to print Hello World, shouldn't print Hello then wait for 5 seconds and print World in the same line?

Possible duplicate of [How to flush output of Python print?](http://stackoverflow.com/questions/230751/how-to-flush-output-of-python-print) — Matthias, Oct 23 '15 at 18:12

score 4 · Accepted Answer · edited May 23 '17 at 11:52

4

No, it shouldn't. "Hello" sits in the output buffer until there's a reason to flush it to the output device. In this case, that "reason" is the end of the program. If you want The delayed effect, add

import sys
sys.stdout.flush()

just before your sleep statement.

See also a more complete discussion here.

edited May 23 '17 at 11:52

Community

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answered Oct 23 '15 at 18:08

Prune

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McGlothlin · Answer 2 · 2015-10-23T18:33:52.590

4

If you set the first print to:

print("Hello ", end='', flush=True)

this should print Hello, then sleep for 5, then print World.

Edit: this only works in Python 3, didn't see the Python 2.7 tag...

edited Oct 23 '15 at 18:33

answered Oct 23 '15 at 18:09

McGlothlin

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Thanks @McGlothlin. This wouldn't work on python2.7 though, `# TypeError: 'flush' is an invalid keyword argument for this function` – Algorithmatic Oct 23 '15 at 18:24
Oops, I'm using Python 3 so didn't catch that! Let me see how you'd do this in Python 2.7... – McGlothlin Oct 23 '15 at 18:31
@MustafaS it looks like Prune has what you want. Sorry about that! – McGlothlin Oct 23 '15 at 18:33

score 0 · Answer 3 · edited May 23 '17 at 12:23

0

import sys
sys.stdout.flush()

This is used to force the Python's print function to screen. See this answer also.

edited May 23 '17 at 12:23

Community

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answered Oct 23 '15 at 18:17

Harnirvair Singh

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Python printing inline with a sleep command

3 Answers3