From: "Chris Günther" <cg_@...>
Date: 2005-03-24T01:54:51+09:00
Subject: Re: Reading and writing a binary file

Carlos wrote:
> [Chris G�nther <cg_@gmx.de>, 2005-03-22 12.29 CET]
> 
>>Thanks Robert,
>>
>>you are absolutely right with your remarks using a block. The code I 
>>posted was just a small copied fraction of the real code, in which I 
>>cannor use a block because the same fd will be stored in a hash for 
>>later usage by another method.
>>Anyway, meanwhile I found the cause of this problem (again you are 
>>right, it was not in the code I posted) , but now I have another related 
>>problem that tricks my mind. I am trying to patch binary data in a file.
>>Unfortunately the data I am patching is not the data I get when reading 
>>it back from the patched binary file.
>>Any ideas??
> 
> 
> All your problems come from the fact that your are opening the file for
> appending ("ab+") instead of for reading ("r+b"). With "ab+", you can set fd.pos=0,
> if you want, but it will always write at the end of file.
> 
> 
> 
Ok, I got it - (maybe only for me) this kind of semanctics is really 
confusing (and not well described either).

Anyway thanks a lot,
Chris