Re: istream buffering

From:

Philipp Kraus <philipp.kraus@flashpixx.de>

Newsgroups:

comp.lang.c++

Date:

Sat, 3 Jul 2010 13:21:56 +0200

Message-ID:

<i0n6gk$an6$1@online.de>

On 2010-07-02 22:30:12 +0200, Kai-Uwe Bux said:

Philipp Kraus wrote:

Hello,

I have a problem to understand stream data. I have one open istream,
which is valid. I would like to read the data from the stream two
times, but I know I can't read the same position twice. Can I copy the
from the stream in a buffer or anything else in which I can read the
data again? I must duplicated the stream content to work with two
seperated (not referenced) copies.

I think, I am not fully grasping your problem. What would be wrong with
something along the following lines:

  int i;
  some_file >> i;
  int j = i;

I don't know the type of the istream. I get in a class method a
reference to the istream and need the content two times. The istream
can hold a large dataset (> 1GB) (or some string data).
I need a cross-plattform (I use boost) solutions for this structur

myclass::input( std::istream x) {
   std::istream y;
   copy(x, y); // -> that's my problem

   mynextmethod(x, y);
}

x and y must have the same content, but they don't be a reference. The
method "mynextmethod" is declared with:
mynextmethod( std::istream&, std::istream );

Can I call the copy-constructor like std::istream y(x) to copy the data?

Thanks