[Tutor] Printing a progress bar

[Danny Yoo]

On Sun, 13 Jun 2004, Dave S wrote:

> Initualy I tried ...
>
> print 'Progress ',
> ..
> loop
>   ...
>   print '#',
> ...
>
> But it appears python does not send a line to the console until it can
> send a CR.

Hi Dave,

Right; what's happening is called "buffering".  Internally, the system
keeps track of the character to be written out, and saves them in a line
buffer.  As soon as we send the system a CR, it'll flush that buffer out
to disk.

(By the way, the same thing happens when we write() to file objects.)

We can manually force a flush by calling the flush() methods on the
standard output file object:

###
def printUnbufferedHash():
    print '#',
    sys.stdout.flush()
###


> PS can anyone tell me the ASCII code to move the cursor left one
> position so I can write a string of
> ..............................................
> becoming
> #########............................
> as progress is made ?

Ah, you're looking for the backspace character '\b'.  No need to remember
the exact ASCII code: use the escape sequence.

But if you're really interested, it's:

###
>>> ord('\b')
8
###

Eight.  *grin*


Good luck to you!