Help me on Backspace please

cakomo cakomo at gmail.com
Fri Jun 27 09:27:26 CEST 2008


On Jun 27, 3:06 am, John Machin <sjmac... at lexicon.net> wrote:
> On Jun 27, 6:32 am, cak... at gmail.com wrote:
>
> > Hi
> > I am a beginner on Python and have a problem..
>
> > I have text file and reading it line by line and there are backspace
> > characters in it like '\b' or anything you want like "#".  I want to
> > replace these chars. with Backspace action. I mean deleting the
> > previous char. and the \b char also. and writing all cleaned text to a
> > file again.
>
> > How can I do that.
>
> I haven't seen anything like that for ... ummm, a very long time. Used
> for bolding and making up your own characters on a daisy-wheel
> printer. Where did you get the file from?
>
> If there are no cases of multiple adjacent backspaces (e.g. "blahfoo\b
> \b\bblah") you can do:
>    new_line = re.sub(r'.\x08', old_line, '')
>
> Note: using \x08 for backspace instead of \b to avoid having to worry
> about how many \ to use in the regex :-)
>
> Otherwise you would need to do something like
>    while True:
>       new_line = re.sub(r'[^\x08]\x08', '', old_line)
>       if new_line == old_line: break
>       old_line = new_line
>
> And if you were paranoid, you might test for any remaining stray
> backspaces, just in case the line contains "illegal" things like
> "\bfoo" or "foo\b\b\b\b" etc.
>
> Cheers,
> John

Thanks John
I will try it but, do you think regex replacement gonna erase the
prev. char.?

Thanks  a lot for your reply.



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