CODEWITHSUNDEEP
pythonpython-3.xfor-looptimeprinting
Robin Dymer
Robin Dymer

Reputation: 13

end argument to print leads to different behavior with time.sleep

I tried to write this script that just prints number after each other on the same line with a one second delay, but it does not work.

Ex this works:

from time import sleep

for n in range(1, 11):
    print(n)
    sleep(1)

But this does not, the program just freezes:

from time import sleep

for n in range(1, 11):
    print(n, end="")
    sleep(1)

Can anyone explain why this is?

Upvotes: 1

Views: 46

Answers (1)

Dimitris Fasarakis Hilliard
Dimitris Fasarakis Hilliard

Reputation: 160407

The program does not freeze, you just need to flush the stream by passing flush=True:

print(n, end="", flush=True)

sys.stdout, the stream that print uses by default, is line-buffered (when in interactive mode), as stated in the documentation:

  • When interactive, standard streams are line-buffered

This means that when the default string used for end (\n) is encountered, a call to flush will be made. Using other strings (i.e '') don't trigger flushing so you'll have to force it by using flush=True.

Upvotes: 2

Related Questions