CRC (was: Re: Help with static data members of class templates)

From: Daryle Walker (darylew_at_[hidden])
Date: 2001-02-14 01:27:04

on 2/11/01 9:02 PM, Jens Maurer at Jens.Maurer_at_[hidden] wrote:

> Daryle Walker wrote:
>> 
>> on 2/8/01 11:02 PM, Jens Maurer at Jens.Maurer_at_[hidden] wrote:
[SNIP iterator v. buffer/length and max stuff]

>> If I make the bit size a run-time parameter, what type is the interim CRC
>> supposed to be?
> 
> std::bitset   ?

Nope.  Bit-sets are compile-time parameterized on the bit size.  Like I
mentioned before, something like a arbitrary-precision type would be needed.
I don't think it's worth these steps to shift bit-size to run-time, users
can live with compile-time for now.  (If they need performance, they would
use the all-compile-time fast version anyway.)

[SNIP minor GCC parsing problems]

>>> Also, gcc doesn't have <ostream>.  Since you're already including
>>> <iostream>, you should forget about <ostream> until gcc gets fixed.
>> 
>> GCC doesn't have <ostream>?!   Where does it put its stream definitions?
> 
> Into "ostream.h".   Don't ask, grab STLport 4.0 :-)

I have one of the few platforms without GCC, so I can't check.  With
problems like no <ostream> or <limits>, I could insist on users getting
STLport.  :-)

>> Or stuff like "endl"?  Is there a guarantee that <ostream>, for proper
>> compilers, is always #included in <iostream>?
> 
> I've never seen a program fail that includes <iostream> and uses
> std::cout for output afterwards.  And it's in all books I know.

I glanced a little bit at the standard.  A type must be fully defined before
declaring an object of that type, so I guess that <iostream> must #include
the definition of std::ostream (and std::basic_ostream<>).  This would
usually mean that it #includes <ostream>, so <iostream> would get std::endl.
I guess that, technically, an implementation could be pathological and
define std::ostream and std::basic_ostream<> in a mini-header that doesn't
include std::endl but will get #included in <iostream> (and <ostream>).
Your trick wouldn't work in that case.

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT mac DOT com