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file position *tell()* works different

M-a-S NO-MAIL at hotmail.com
Fri Sep 19 06:17:15 EDT 2003 
I'm not sure if that't the reason, but the binary mode for reading is 'rb'.
Actually, the order of 'r' and 'b' shouldn't matter. But the '+' has a different
meaning: the file should allow "opposite" access as well, e.g. 'r+', 'rb+'
means that you can write to the file too, while 'w+' means: open it for
writing but permit reading too. You can try to say 'rt' for the read/text mode.

Anyway, you program works under Windows XP/Python 2.3 as expected:

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Home\Programming\Python\2>py
Python 2.3 (#46, Jul 29 2003, 18:54:32) [MSC v.1200 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>^Z

C:\Home\Programming\Python\2>test.py
Filepointer:   0
Filepointer:  12
Filepointer:  24
Filepointer:  35
Filepointer:  54

Filepointer:   0
Filepointer:  12
Filepointer:  24
Filepointer:  35
Filepointer:  54

I'm sorry if it doesn't help. The bug must be somewhere else then.

M-a-S


"Peter Abel" <p-abel at t-online.de> wrote in message news:13a533e8.0309190137.2df0cc60 at posting.google.com...
> Hi all,
> I'm working under W2k with
> Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32
>
> I have a file *test_data.txt* with the following content:
> 0123456789
> 0123456789
> abcdefghi
> ABCDEFGHIJKLMNOPQ
>
> and I work on it with the following python script:
>
> # Open NOT in binary mode
> fp=file('test_data.txt','r')
> a='xx'
> while a:
>   print 'Filepointer: %3d' %  fp.tell()
>   a=fp.readline()
> fp.close()
>
> print
>
> # Open IN binary mode
> fp=file('test_data.txt','r+b')
> a='xx'
> while a:
>   print 'Filepointer: %3d' %  fp.tell()
>   a=fp.readline()
> fp.close()
>
> Now, when test_data.txt is saved in PC-mode with 0xC, 0xA as newline
> it works correct.
> But when I save the file in UNIX-Mode with 0xA as newline,
> my script gives me the following output, where that one with
> the file not opened in binary mode is wrong:
> Filepointer:   0
> Filepointer:   7
> Filepointer:  19
> Filepointer:  30
> Filepointer:  49
> Filepointer:  51
>
> Filepointer:   0
> Filepointer:  11
> Filepointer:  22
> Filepointer:  32
> Filepointer:  50
> Filepointer:  51
>
> When I try this under HP-UX it works fine in both cases.
> So I wonder if the function *tell()* is not correctly implemented under win32.
>
> Regards
> Peter
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