problem with read() write()

[Matt Nordhoff]

Gertjan Klein wrote:
> Alf P. Steinbach wrote:
> 
>> So with 'w+' the only way to get garbage is if 'read' reads beyond the end of 
>> file, or 'open' doesn't conform to the documentation.
> 
> It does read beyond the end of file. This is perhaps the way the
> underlying C library works, but it looks like an "unexpected feature"
> (read: bug) to me.
> 
> I reproduced (with Python 2.5.2 on WinXP) the code the OP wrote after
> creating an empty (0-byte) test file; after the write() the read()
> returns random garbage. I can't imagine why anyone would want that
> behaviour. The file grew to be 4099 bytes after f.close(). I wrote
> 'hello' to it, so the length of garbage added was 4094 bytes, which I
> find a strange number also.
> 
> I would have expected the read to return nothing. Can anyone explain or
> even defend this behaviour?
> 
> Gertjan.

I wonder, does it still happen if you open the file in binary mode?
(Stick a "b" in the file mode.) It could be some Windows text mode
craziness.
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