What does sys.stdout.flush() do?

[D. Xenakis]

Somewhere i read..
sys.stdout.flush(): Flush on a file object pushes out all the data that has been buffered to that point.

Can someone post here a script example with sys.stdout.flush(), where in case i commented that i could understand what the difference really would be?

Whenever i try to remove that line (in scripts that i find online), i cant find any differences. I've just noticed that it is usually called right after sys.stdout.write(..)
thx

 

[Peter Otten]

Somewhere i read..
sys.stdout.flush(): Flush on a file object pushes out all the data that
has been buffered to that point.

Can someone post here a script example with sys.stdout.flush(), where in
case i commented that i could understand what the difference really would
be?

Whenever i try to remove that line (in scripts that i find online), i cant
find any differences. I've just noticed that it is usually called right
after sys.stdout.write(..) thx

Use time.sleep() to see the effects of (line) buffering. Type the following
in your interactive interpreter and be enlightened
.... print i,
.... time.sleep(.1)
....
0 1 2 3 4 5 6 7 8 9.... print i,
.... sys.stdout.flush()
.... time.sleep(.1)
....
0 1 2 3 4 5 6 7 8 9

 

[John Gordon]

Can someone post here a script example with sys.stdout.flush(), where in
case i commented that i could understand what the difference really would
be?

Depending what sys.stdout is connected to (a file, the screen, a pipe,
etc.), data doesn't necessarily get written right away. In particular,
screen output often waits until it receives a newline before displaying
anything.

flush() makes sure it all gets written *right now*.