Re: Byte-oriented streaming

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Tue, 5 Feb 2008 02:40:38 -0800 (PST)

Message-ID:

<df11ce9d-8052-4649-bfe5-51c9ef5bc477@l1g2000hsa.googlegroups.com>

On Feb 4, 7:06 am, Jeff Schwab <j...@schwabcenter.com> wrote:

Chris Swiedler wrote:

Is there a C++ STL or boost class hierarchy for byte streaming similar
to ostream and friends for character streaming? Those classes do not
seem designed to support byte streaming (e.g. they interpret
whitespace and null bytes specially).

What leads you to believe that? Can post a short example of what's not
working the way you want it to?

The ostream and istream interfaces are meant to allow whatever
kind of I/O you need, via differing implementations (rdbufs).

That's not true. The abstraction behind ostream and istream is
a stream of text. The streambuf's handle the different sinks
and sources, but have no effect whatsoever on the format.

In addition, in istream at least, the convention is that within
the text, white space is the separator, and that multiple
white space is coalesed into a single separator. You can, in
special cases, inhibit this skipping of white space, but it is
the general rule. (On the other hand, "white space" is locale
dependent, so you can play tricks with the locale. I tend to
see this as abuse, in some way, but others don't.)

strstream gives null bytes special meanings, but stringstream
(for example) does not. Depending on your OS (I'm looking at
you, MS), file I/O may require a binary flag; I've never had
to specify it on any flavor of Unix or Linux, though.

The distinction between binary and text modes in filebuf (and
indirectly in ifstream and ofstream) is only concerned with file
types at the OS level, and how the OS interpretation of "text"
is mapped to the C++ interpretation. Unix and its look-alikes
have only one file type, and for historical reasons, C++ has
adopted it's view of what a text file looks like, so no mapping
is necessary. Unix is rather an exception, here, however.

Note that this "binary" is actually a misnomer, since it only
affects the file mode---the abstraction is still a stream of
text.

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James Kanze (GABI Software) email:james.kanze@gmail.com
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