[Mingw-users] Re: fseek with SEEK_SET

[Benjamin R. <Ben...@ep...>]

Hi Bernd, Oscar,


> ml...@mu... writes:
>> when fseek is called, for example, like this:
>>
>> file_pointer=fopen(filename,"ab");
>> fseek(file_pointer,4,SEEK_SET);
>>
>> it actually seeks to the end of the file instead of the 4th byte.
>> Is this a known problem under Windows ?

Oscar Fuentes <of...@wa...> writes:
> A look at the C standard should clarify things, but it's too late
> here.

If I may, C89 says:

  Opening a file with append mode ('a' [...]) causes all subsequent
  writes to the file to be forced to the then current end-of-file,
  regardless of intervening calls to the fseek function.

It doesn't seem to mention how ftell() is supposed to behave, but I
guess that just ignoring fseek() on such a stream is reasonable.

Things get more interesting with "a+b", because that should allow
reading at any place in the file, so with such a stream fseek() can
not be a no-op.


benny