Groups > comp.lang.python > #20552

Re: Undoing character read from file

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From	Neil Cerutti <neilc@norwich.edu>
Newsgroups	comp.lang.python
Subject	Re: Undoing character read from file
Date	17 Feb 2012 13:12:07 GMT
Organization	Norwich University
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On 2012-02-16, MRAB <python@mrabarnett.plus.com> wrote:
> On 16/02/2012 23:10, Emeka wrote:
>> Hello All,
>>
>> I know about seek and tell while using readline. What about if I am
>> using read, and I want to undo the last character I just read(to return
>> it back to the stream). How do I achieve this?
>>
> Try:
>
>      f.seek(-1, 1)
>
> It seeks -1 relative to the current position (the second
> argument defaults to 0 for relative to start of file).

Unless it's a stream opened in binary mode this will not work.
You'd need to maintain a n-character length buffer instead, with
n being the maximum number of characters you'd like to be able to
put back.

-- 
Neil Cerutti

Thread

Re: Undoing character read from file MRAB <python@mrabarnett.plus.com> - 2012-02-16 23:31 +0000
  Re: Undoing character read from file Neil Cerutti <neilc@norwich.edu> - 2012-02-17 13:12 +0000
    Re: Undoing character read from file Dave Angel <d@davea.name> - 2012-02-17 22:58 -0500

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