From oliver at first.in-berlin.de  Thu Jun  9 13:27:15 2011
From: oliver at first.in-berlin.de (oliver)
Date: Thu, 9 Jun 2011 13:27:15 +0200
Subject: [Rd] "warning: assignment discards qualifiers from pointer
 target type"
In-Reply-To: <86C9E656-BCF4-48C8-8016-877DFAA0D158@r-project.org>
References: <20110607130854.GA4510@siouxsie> <4DEE3786.5000800@gmail.com>
	<alpine.LFD.2.02.1106071606010.26985@gannet.stats.ox.ac.uk>
	<20110608160839.GA11746@siouxsie>
	<B68723F7-F66B-40FD-AE38-0A88C0C51B82@r-project.org>
	<20110609001731.GA3565@siouxsie> <20110609003209.GA4839@siouxsie>
	<86C9E656-BCF4-48C8-8016-877DFAA0D158@r-project.org>
Message-ID: <20110609112715.GA3855@siouxsie>

On Wed, Jun 08, 2011 at 08:35:34PM -0400, Simon Urbanek wrote:
> 
> On Jun 8, 2011, at 8:32 PM, oliver wrote:
> 
> > On Thu, Jun 09, 2011 at 02:17:31AM +0200, oliver wrote:
> > [...]
> >> OK, I looked at this now.
> >> 
> >> LENGTH() checks the length of the vector.
> >> 
> >> Good to know this.
> >> 
> >> So the problem of a vector of length 0 can be with any arguments of type SEXP,
> >> hence I will need to check ANY arg on it's length.
> >> 
> >> This is vital to stability under any situation.
> >> 
> >> Thanks for this valuable hint!
> >> 
> >> I will add checks for all my SEXP-args.
> > [...]
> > 
> > Hey, LENGTH() does not work with String-vectors! :(
> > 
> 
> Of course it does ...
> 
> 

It does not so on my R 2.10.1 installation.


In the R-Shell I get:

  ==============================
  > length(c())
  [1] 0
  > 
  ==============================

So c() is vec of length 0.

When I feed my readjpeg() with c() as filename arg,

testing with:
====================================================
  if( LENGTH( filename_sexp ) < 1 )
  {
    error("LENGTH( filename_sexp ) < 1");
    //error("filename can't be vector of length 0");
  }
  else
  {
    error("LENGTH( filename_sexp ) is not < 1");
  }
====================================================


I got:
  Error in readjpeg(filename = c()) : LENGTH( filename_sexp ) is not < 1


You can explain why?


Ciao,
   Oliver



[Rd] "warning: assignment discards qualifiers from pointer target type"
oliver