Simple (?) question about print statement

Fredrik Lundh fredrik at pythonware.com
Wed Dec 14 22:04:55 CET 2005


"TY" <aqteon at yahoo.com> wrote:

> I have this little simple script:
>
> for i in range(10):
>     for j in range(5000000): pass     # Timing-delay loop
>     print i
>
> When you run it, it behaves as you would expect -- it prints 0 <pause>
> on the next line prints 1 <pause> on the next line prints 2 <pause>
> etc.
>
> But if you add a comma at the end of print statement on the last line
> like this:
>
> for i in range(10):
>     for j in range(5000000): pass     # Timing-delay loop
>     print i,
>
> Now it does this:
>
> <long pause> then prints 0 1 2 3 4 5 6 7 8 9 all at once.
>
> Why?????
>
> How can I make it to print each numbers on the same line with pauses in
> between them?

because stdout is line buffered.

try this instead:

    import time, sys

    for i in range(10):
        time.sleep(0.8) # seconds; tune as necessary
        print i,
        sys.stdout.flush() # flush stdout
    print

</F>






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