Re: [Mingw-users] ifstream.readsome... more info

[Oscar F. <of...@wa...>]

Igor Gnip <gn...@di...> writes:

> http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
>
> apparently bug has been fixed ...  but not in mingw (yet)
>
> need help to get around this one...

As your test case outputs the same on g++ 3.2.2, Borland 5.5.1 and on
Intel v7, I suspect the problem is elsewhere.

The docs for readsome says that it depends of the result of
rdbuf()->in_avail(). Well, this means that you can't read so many
characters as you want on just one chunk. The maximun value for
in_avail() is the *buffer* size, which seems 512 bytes by
default. in_avail() returns the available characters on the
buffer. Next problem is getting the buffer filled before calling
readsome. Sure there is a method somewhere. For your test case,
putting

fs.get();

just before the readsome fills the buffer and then readsome reads the
other 511 characters.

IMHO, using the C++ IOstreams for reading so much binary info is a
mistake, both on terms of complexity and performance. Better stick to
the C library or the WinAPI.

HTH.

-- 
Oscar